M/S Mic Question

[locosoundman]

If the mid mic were a Schoeps CMC64 and you had a choice between a U87
and a C414B-ULS, for the side mic, which would you prefer, and why, on
any or all of the following sources:

Choir, piano, harpsichord, guitar, drum OH

Thank you.

[Scott Dorsey]

locosoundman > wrote:
>If the mid mic were a Schoeps CMC64 and you had a choice between a U87
>and a C414B-ULS, for the side mic, which would you prefer, and why, on
>any or all of the following sources:
>
>Choir, piano, harpsichord, guitar, drum OH

I would go mono and skip the side mike entirely if those were my options.

Neither the U87 or the C414 are going to be anything approaching the
same response as the C414, so that objects on the edge of the sound field
will sound different than those in the center. In both cases, those mikes
are a lot brighter than the Schoeps, so stuff on the edge of the field will
become brighter. My feeling is that if you have to use an unmatched side
mike, you'd want something duller sounding than the mid mike, like a Beyer
M130, because having the edges of the soundfield duller than the center seems
less annoying.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

locosoundman > wrote:
>If the mid mic were a Schoeps CMC64 and you had a choice between a U87
>and a C414B-ULS, for the side mic, which would you prefer, and why, on
>any or all of the following sources:
>
>Choir, piano, harpsichord, guitar, drum OH

I would go mono and skip the side mike entirely if those were my options.

Neither the U87 or the C414 are going to be anything approaching the
same response as the C414, so that objects on the edge of the sound field
will sound different than those in the center. In both cases, those mikes
are a lot brighter than the Schoeps, so stuff on the edge of the field will
become brighter. My feeling is that if you have to use an unmatched side
mike, you'd want something duller sounding than the mid mike, like a Beyer
M130, because having the edges of the soundfield duller than the center seems
less annoying.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers]

In article > writes:

> If the mid mic were a Schoeps CMC64 and you had a choice between a U87
> and a C414B-ULS, for the side mic, which would you prefer, and why

The C414, because it's easier to mount.

I think I'd prefer a Sennheiser MKH30 though. It has a better
bi-directional pattern than either of the large diaphragm mics you
offered as a choice, it's very quiet, and it's easy to use.

> Choir, piano, harpsichord, guitar, drum OH

Understand that you don't choose an M-S configuration based on the
instrument, you choose it based on the room. In a bad room, any M-S
arrangement could give emphatically poor results on any of those
sources.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

[Mike Rivers]

In article > writes:

> If the mid mic were a Schoeps CMC64 and you had a choice between a U87
> and a C414B-ULS, for the side mic, which would you prefer, and why

The C414, because it's easier to mount.

I think I'd prefer a Sennheiser MKH30 though. It has a better
bi-directional pattern than either of the large diaphragm mics you
offered as a choice, it's very quiet, and it's easy to use.

> Choir, piano, harpsichord, guitar, drum OH

Understand that you don't choose an M-S configuration based on the
instrument, you choose it based on the room. In a bad room, any M-S
arrangement could give emphatically poor results on any of those
sources.



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

[Bob Cain]

Scott Dorsey wrote:
> My feeling is that if you have to use an unmatched side
> mike, you'd want something duller sounding than the mid mike, like a Beyer
> M130, because having the edges of the soundfield duller than the center seems
> less annoying.

OTOH, a good linear phase equalizer applied to the side
mic's recording could tame whatever you use. Linear phase
so as not to screw up the recorded phase relationships. I
don't generally like linear phase equalization but it has
its applications and this would be one of them.

A gotcha for MS is always the response symmetry of the side
mic. In general this is not a terribly important
requirement because one side receives a considerably
different kind of signal than the other but in an MS that's
not true.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Scott Dorsey wrote:
> My feeling is that if you have to use an unmatched side
> mike, you'd want something duller sounding than the mid mike, like a Beyer
> M130, because having the edges of the soundfield duller than the center seems
> less annoying.

OTOH, a good linear phase equalizer applied to the side
mic's recording could tame whatever you use. Linear phase
so as not to screw up the recorded phase relationships. I
don't generally like linear phase equalization but it has
its applications and this would be one of them.

A gotcha for MS is always the response symmetry of the side
mic. In general this is not a terribly important
requirement because one side receives a considerably
different kind of signal than the other but in an MS that's
not true.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[WillStG]

<< (locosoundman) >>
<< If the mid mic were a Schoeps CMC64 and you had a choice between a U87
and a C414B-ULS, for the side mic, which would you prefer, and why, on
any or all of the following sources:

Choir, piano, harpsichord, guitar, drum OH >>

I would use mismatched mics in MS if I had a small sounding room and I
wanted it to sound bigger. Were I doing that on a small choir and drums, I
would use the U87 as the sides mic as it's smoother sounding than a 414B-ULS.
Unless the micpres were on a Mackie mixer, which is pretty unkind to U87's,
probably then the 414B would sound better on the sides. Unless it didn't sound
better of course...

Guitar and piano I would first try close stereo micing with mismatched
pairs in cardiod or figure 8 patterns, rather than distant micing in MS.

Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

<< (locosoundman) >>
<< If the mid mic were a Schoeps CMC64 and you had a choice between a U87
and a C414B-ULS, for the side mic, which would you prefer, and why, on
any or all of the following sources:

Choir, piano, harpsichord, guitar, drum OH >>

I would use mismatched mics in MS if I had a small sounding room and I
wanted it to sound bigger. Were I doing that on a small choir and drums, I
would use the U87 as the sides mic as it's smoother sounding than a 414B-ULS.
Unless the micpres were on a Mackie mixer, which is pretty unkind to U87's,
probably then the 414B would sound better on the sides. Unless it didn't sound
better of course...

Guitar and piano I would first try close stereo micing with mismatched
pairs in cardiod or figure 8 patterns, rather than distant micing in MS.

Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

<< (WillStG) >>
<< Guitar and piano I would first try close stereo micing with mismatched
pairs in cardiod or figure 8 patterns, rather than distant micing in MS. >>

Actually by close micing I mean spaced pairs, not X/Y stereo micing, like
one mic on the guitar neck and one near the bridge.


Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

<< (WillStG) >>
<< Guitar and piano I would first try close stereo micing with mismatched
pairs in cardiod or figure 8 patterns, rather than distant micing in MS. >>

Actually by close micing I mean spaced pairs, not X/Y stereo micing, like
one mic on the guitar neck and one near the bridge.


Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[David Satz]

Scott Dorsey wrote:

> Neither the U87 or the C414 are going to be anything approaching the
> same response as the C414, so that objects on the edge of the sound
> field will sound different than those in the center. In both cases,
> those mikes are a lot brighter than the Schoeps, so stuff on the edge
> of the field will become brighter. My feeling is that if you have to
> use an unmatched side mike, you'd want something duller sounding than
> the mid mike, like a Beyer M130, because having the edges of the
> soundfield duller than the center seems less annoying.

(Assuming that in the second line you meant to write "the CMC 64" ...)
A figure-8 with rising high frequency response--especially if that
response is not evenly maintained at all angles of sound incidence--
will definitely skew the stereo imaging.

But the issue which I would encourage folks to think about isn't the
match or mismatch between the M and S microphones of a pair. Rather,
I see the accuracy of the figure-8 microphone's directional pattern,
and the consistency of that pattern throughout its bandwidth, as the
main things which determine its suitability for M/S use at all--of
course assuming that its noise and distortion are low enough, too.

The S microphone in an M/S pair has a very specific function: to
produce the difference information between the eventual left and right
stereo channels. The better it can perform that one function--the more
accurate its figure-8 polar pattern is, and the flatter its frequency
response is--the more freedom one then has to choose an M microphone
with whatever coloring (or lack thereof) and pattern one prefers.

Ideally, an S microphone should be chosen such that its sonic character
is not a significant factor in the eventual stereo result.

The U 87's figure-8 setting is a little bright on axis and rolls off
at the sides. It's a nice sound for a number of other uses--but of
the two microphones proposed, I'd sooner use a C 414B-ULS as the S
microphone for M/S pickup, I think.

--best regards

[David Satz]

Scott Dorsey wrote:

> Neither the U87 or the C414 are going to be anything approaching the
> same response as the C414, so that objects on the edge of the sound
> field will sound different than those in the center. In both cases,
> those mikes are a lot brighter than the Schoeps, so stuff on the edge
> of the field will become brighter. My feeling is that if you have to
> use an unmatched side mike, you'd want something duller sounding than
> the mid mike, like a Beyer M130, because having the edges of the
> soundfield duller than the center seems less annoying.

(Assuming that in the second line you meant to write "the CMC 64" ...)
A figure-8 with rising high frequency response--especially if that
response is not evenly maintained at all angles of sound incidence--
will definitely skew the stereo imaging.

But the issue which I would encourage folks to think about isn't the
match or mismatch between the M and S microphones of a pair. Rather,
I see the accuracy of the figure-8 microphone's directional pattern,
and the consistency of that pattern throughout its bandwidth, as the
main things which determine its suitability for M/S use at all--of
course assuming that its noise and distortion are low enough, too.

The S microphone in an M/S pair has a very specific function: to
produce the difference information between the eventual left and right
stereo channels. The better it can perform that one function--the more
accurate its figure-8 polar pattern is, and the flatter its frequency
response is--the more freedom one then has to choose an M microphone
with whatever coloring (or lack thereof) and pattern one prefers.

Ideally, an S microphone should be chosen such that its sonic character
is not a significant factor in the eventual stereo result.

The U 87's figure-8 setting is a little bright on axis and rolls off
at the sides. It's a nice sound for a number of other uses--but of
the two microphones proposed, I'd sooner use a C 414B-ULS as the S
microphone for M/S pickup, I think.

--best regards

[Sugarite]

> If the mid mic were a Schoeps CMC64 and you had a choice between a U87
> and a C414B-ULS, for the side mic, which would you prefer, and why, on
> any or all of the following sources:
>
> Choir, piano, harpsichord, guitar, drum OH

I assume you're talking about distant micing, since MS is inappropriate up
close.

I have never liked any MS rig I've tried. Geometricly it makes sense, but
there's just no mic pair for the job. Large diaphrams have
poor/inconsistent off-axis response, plus are inconsistent front-to-back
too. A small diaphram fig-8 would make much more sense, but they don't
exist, except by using two opposing cardioid capsules, which introduces
phase issues from the slight displacement between the two, in addition to
the problems from the displacement between the mono and side mics...

Frankly I've been much happier with coincident XY wherever MS might be used.
People complain that XY isn't always "wide" enough, but it's so easy with a
few custom cables to isolate the side channel using the inserts and a stereo
auxiliary, and it's even simpler with Waves Stereo Imager in the box, and
the result is far less comprimised than a MS array IMO.

But unless there's sound reinforcement involved, I always prefer an ORTF-ish
spaced pair, again small diaphram. Whatever you do, don't do any "widening"
to a spaced pair or it's a world of phase nastiness. Get it right with mic
positioning and room tuning. Drum overheads shouldn't need anything on them
in the mix. If a $300 pair of Rode NT5's can pull that off nicely, you'll
have no trouble in your price range.

[Sugarite]

> If the mid mic were a Schoeps CMC64 and you had a choice between a U87
> and a C414B-ULS, for the side mic, which would you prefer, and why, on
> any or all of the following sources:
>
> Choir, piano, harpsichord, guitar, drum OH

I assume you're talking about distant micing, since MS is inappropriate up
close.

I have never liked any MS rig I've tried. Geometricly it makes sense, but
there's just no mic pair for the job. Large diaphrams have
poor/inconsistent off-axis response, plus are inconsistent front-to-back
too. A small diaphram fig-8 would make much more sense, but they don't
exist, except by using two opposing cardioid capsules, which introduces
phase issues from the slight displacement between the two, in addition to
the problems from the displacement between the mono and side mics...

Frankly I've been much happier with coincident XY wherever MS might be used.
People complain that XY isn't always "wide" enough, but it's so easy with a
few custom cables to isolate the side channel using the inserts and a stereo
auxiliary, and it's even simpler with Waves Stereo Imager in the box, and
the result is far less comprimised than a MS array IMO.

But unless there's sound reinforcement involved, I always prefer an ORTF-ish
spaced pair, again small diaphram. Whatever you do, don't do any "widening"
to a spaced pair or it's a world of phase nastiness. Get it right with mic
positioning and room tuning. Drum overheads shouldn't need anything on them
in the mix. If a $300 pair of Rode NT5's can pull that off nicely, you'll
have no trouble in your price range.

[Bob Cain]

Sugarite wrote:
> A small diaphram fig-8 would make much more sense, but they don't
> exist, except by using two opposing cardioid capsules, which introduces
> phase issues from the slight displacement between the two, in addition to
> the problems from the displacement between the mono and side mics...

This is an excellent solution to the problem, actually. If
you mount the two back to back cardiods one atop the other
you will largely avoid the non-coincidence problem. It's a
DIY proposition, though, because you pretty much have to use
raw capsules.

Using three identical capsules, one for the front and two
for the side and reasonably matched is pretty near optimal
for M/S IMO.

>
> Frankly I've been much happier with coincident XY wherever MS might be used.
> People complain that XY isn't always "wide" enough, but it's so easy with a
> few custom cables to isolate the side channel using the inserts and a stereo
> auxiliary, and it's even simpler with Waves Stereo Imager in the box, and
> the result is far less comprimised than a MS array IMO.

Since the coincident XY can be easily matrixed back to MS in
a DAW for width manipulation, there really isn't a hell of a
lot of difference except that it is simpler.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:
> A small diaphram fig-8 would make much more sense, but they don't
> exist, except by using two opposing cardioid capsules, which introduces
> phase issues from the slight displacement between the two, in addition to
> the problems from the displacement between the mono and side mics...

This is an excellent solution to the problem, actually. If
you mount the two back to back cardiods one atop the other
you will largely avoid the non-coincidence problem. It's a
DIY proposition, though, because you pretty much have to use
raw capsules.

Using three identical capsules, one for the front and two
for the side and reasonably matched is pretty near optimal
for M/S IMO.

>
> Frankly I've been much happier with coincident XY wherever MS might be used.
> People complain that XY isn't always "wide" enough, but it's so easy with a
> few custom cables to isolate the side channel using the inserts and a stereo
> auxiliary, and it's even simpler with Waves Stereo Imager in the box, and
> the result is far less comprimised than a MS array IMO.

Since the coincident XY can be easily matrixed back to MS in
a DAW for width manipulation, there really isn't a hell of a
lot of difference except that it is simpler.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Hal Laurent]

"Sugarite" > wrote in message
...

> A small diaphram fig-8 would make much more sense, but they don't
> exist, except by using two opposing cardioid capsules

Schoeps makes a single-diaphragm figure-8 capsule (the MK8).

Hal Laurent
Baltimore

[Hal Laurent]

"Sugarite" > wrote in message
...

> A small diaphram fig-8 would make much more sense, but they don't
> exist, except by using two opposing cardioid capsules

Schoeps makes a single-diaphragm figure-8 capsule (the MK8).

Hal Laurent
Baltimore

[Scott Dorsey]

Hal Laurent > wrote:
>"Sugarite" > wrote in message
...
>
>> A small diaphram fig-8 would make much more sense, but they don't
>> exist, except by using two opposing cardioid capsules
>
>Schoeps makes a single-diaphragm figure-8 capsule (the MK8).

This is a nontrivial thing to do. Sennheiser also does one in the MKH
line, but the RF electronics on those microphones already requires some
internal capsule equalization. Schoeps manages it without doing so, and
damned if I know how they manage it, but as far as I know nobody else has
done it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Hal Laurent > wrote:
>"Sugarite" > wrote in message
...
>
>> A small diaphram fig-8 would make much more sense, but they don't
>> exist, except by using two opposing cardioid capsules
>
>Schoeps makes a single-diaphragm figure-8 capsule (the MK8).

This is a nontrivial thing to do. Sennheiser also does one in the MKH
line, but the RF electronics on those microphones already requires some
internal capsule equalization. Schoeps manages it without doing so, and
damned if I know how they manage it, but as far as I know nobody else has
done it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Dave]

Which pairing would make the best M/S rig using Schoeps mics: MK41 & MK8 or
MK4 & MK8?

dave

>>
>>> A small diaphram fig-8 would make much more sense, but they don't
>>> exist, except by using two opposing cardioid capsules
>>
>>Schoeps makes a single-diaphragm figure-8 capsule (the MK8).
>
> This is a nontrivial thing to do. Sennheiser also does one in the MKH
> line, but the RF electronics on those microphones already requires some
> internal capsule equalization. Schoeps manages it without doing so, and
> damned if I know how they manage it, but as far as I know nobody else has
> done it.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

[Dave]

Which pairing would make the best M/S rig using Schoeps mics: MK41 & MK8 or
MK4 & MK8?

dave

>>
>>> A small diaphram fig-8 would make much more sense, but they don't
>>> exist, except by using two opposing cardioid capsules
>>
>>Schoeps makes a single-diaphragm figure-8 capsule (the MK8).
>
> This is a nontrivial thing to do. Sennheiser also does one in the MKH
> line, but the RF electronics on those microphones already requires some
> internal capsule equalization. Schoeps manages it without doing so, and
> damned if I know how they manage it, but as far as I know nobody else has
> done it.
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

[Eric K. Weber]

Why is this so difficult....
> Sugarite wrote:
> > A small diaphram fig-8 would make much more sense, but they don't
> > exist,


The following small diaphram solutions do exist....

Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
http://www.sennheiser.com/sennheiser/icm.nsf/root/03109

Schoeps also has small diaphragm figure 8..
http://www.schoeps.de/E-2004/figure-8.html
http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Rgds:
Eric

[Eric K. Weber]

Why is this so difficult....
> Sugarite wrote:
> > A small diaphram fig-8 would make much more sense, but they don't
> > exist,


The following small diaphram solutions do exist....

Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
http://www.sennheiser.com/sennheiser/icm.nsf/root/03109

Schoeps also has small diaphragm figure 8..
http://www.schoeps.de/E-2004/figure-8.html
http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Rgds:
Eric

[Bob Cain]

Eric K. Weber wrote:
> Why is this so difficult....
>
>>Sugarite wrote:
>>
>>>A small diaphram fig-8 would make much more sense, but they don't
>>>exist,
>
> The following small diaphram solutions do exist....
>
> Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
> http://www.sennheiser.com/sennheiser/icm.nsf/root/03109

I would consider these much too large for the back to back
solution. The mic bodies would create signifigant near
reflections into the array that would booger up the
frequency response.

>
> Schoeps also has small diaphragm figure 8..
> http://www.schoeps.de/E-2004/figure-8.html
> http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Yes, top tier solution and you'll pay accordingly. I tend
to forget things that are way outside my ability to
consider. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Eric K. Weber wrote:
> Why is this so difficult....
>
>>Sugarite wrote:
>>
>>>A small diaphram fig-8 would make much more sense, but they don't
>>>exist,
>
> The following small diaphram solutions do exist....
>
> Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
> http://www.sennheiser.com/sennheiser/icm.nsf/root/03109

I would consider these much too large for the back to back
solution. The mic bodies would create signifigant near
reflections into the array that would booger up the
frequency response.

>
> Schoeps also has small diaphragm figure 8..
> http://www.schoeps.de/E-2004/figure-8.html
> http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

Yes, top tier solution and you'll pay accordingly. I tend
to forget things that are way outside my ability to
consider. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:

> It's still a moot point though, you really need spaced cardioids to get the
> time differential aspect of natural imaging.

I strongly disagree. Coincident, intensity based methods
are in wide and sucessful use. It's a matter of taste.

The time differential that is recorded gets so munged by the
time domain mangling that speakers and rooms effect that on
reproduction it in no way resembles what was recorded.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:

> It's still a moot point though, you really need spaced cardioids to get the
> time differential aspect of natural imaging.

I strongly disagree. Coincident, intensity based methods
are in wide and sucessful use. It's a matter of taste.

The time differential that is recorded gets so munged by the
time domain mangling that speakers and rooms effect that on
reproduction it in no way resembles what was recorded.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Richard Kuschel]

>However, as the Schoeps website says about the MK8, "directional pattern
>almost completely identical at all frequencies." Every fig-8 mic can share
>the exact same description, because they're all unequal front-to-rear, which
>translates to unequal left-to-right in MS.
>

Why would that be?
If using a single diaphragm figute 8 (Schoeps, Sennheiser and Neumann) wouldn't
the response be the same front to back.

I can see that slightly off axis that the response might not be perfect at all
frequencies due to diaphragm size.

Also, most ribbon figure 8's have the same front and back frequency response
with the exception of the Royer R-121 which was designed to handle high SPL's
and this changed the response.


Richard H. Kuschel
"I canna change the law of physics."-----Scotty

[Richard Kuschel]

>However, as the Schoeps website says about the MK8, "directional pattern
>almost completely identical at all frequencies." Every fig-8 mic can share
>the exact same description, because they're all unequal front-to-rear, which
>translates to unequal left-to-right in MS.
>

Why would that be?
If using a single diaphragm figute 8 (Schoeps, Sennheiser and Neumann) wouldn't
the response be the same front to back.

I can see that slightly off axis that the response might not be perfect at all
frequencies due to diaphragm size.

Also, most ribbon figure 8's have the same front and back frequency response
with the exception of the Royer R-121 which was designed to handle high SPL's
and this changed the response.


Richard H. Kuschel
"I canna change the law of physics."-----Scotty

[David Satz]

"Dave" wrote:

> Which pairing would make the best M/S rig using Schoeps mics:
> MK41 & MK8 or MK4 & MK8?

Many people use either of those combinations for M/S. In principle any
pattern of microphone that you like can be the "M" microphone in an M/S
pair, but the results will differ in at least two ways:

[1] The stereo imaging--a supercardioid "M" microphone will give more
precise localization and a more even "spread" (perceived left-right
distribution) of the discrete sound sources across the stereo stage
width than a cardioid can offer. With cardioids, the discrete sound
sources tend to clump more toward the middle in playback.

However, if you are recording a very wide group of sound sources, there
will be more of a limit as to how close you can bring a supercardioid-
based pair in toward the performers. The angle between the -3 dB points
of a supercardioid pattern is narrower than that angle is for a cardioid;
that's what determines the maximum stereo pickup angle in this case.

[2] With the MK 41 (supercardioid), for any given miking distance, you
will get somewhat less reverberant sound than with the MK 4 (cardioid).
But that also depends on your miking distance and the amount of "S"
signal which you feed into the matrix when you go from M/S to L/R.

If you want to get a certain amount of reverberance overall, you can
get it with either setup--but there will be more of a stereo aspect to
the reflected sound energy in the MK 41 setup, since more of it will
be coming from the "S" microphone than it would with the MK 4.

Also, the reverberant energy picked up by a supercardioid will generally
be more diffuse, longer delayed and better blended than with a cardioid,
since a greater proportion of the indirect sound which it does pick up
will arrive through the rear lobe of the supercardioid. Since that
lobe is aimed away from the direct sound source, it will receive sound
that has traveled farther on average than the reflected sound which is
picked up at the sides of a cardioid. Thus the reverberant sound will
have undergone more high-frequency absorption and will be more delayed,
which are both things that help mellow out the reverberant sound and
keep it from messing up the front stereo image.

So in general, I favor using a supercardioid "M" microphone. If I have
to cover so wide an area that I can't use that narrow a pattern, then a
centered, coincident stereo pickup probably isn't the best idea anyway
(unless mono compatibility is an absolute requirement).

--best regards

[David Satz]

"Dave" wrote:

> Which pairing would make the best M/S rig using Schoeps mics:
> MK41 & MK8 or MK4 & MK8?

Many people use either of those combinations for M/S. In principle any
pattern of microphone that you like can be the "M" microphone in an M/S
pair, but the results will differ in at least two ways:

[1] The stereo imaging--a supercardioid "M" microphone will give more
precise localization and a more even "spread" (perceived left-right
distribution) of the discrete sound sources across the stereo stage
width than a cardioid can offer. With cardioids, the discrete sound
sources tend to clump more toward the middle in playback.

However, if you are recording a very wide group of sound sources, there
will be more of a limit as to how close you can bring a supercardioid-
based pair in toward the performers. The angle between the -3 dB points
of a supercardioid pattern is narrower than that angle is for a cardioid;
that's what determines the maximum stereo pickup angle in this case.

[2] With the MK 41 (supercardioid), for any given miking distance, you
will get somewhat less reverberant sound than with the MK 4 (cardioid).
But that also depends on your miking distance and the amount of "S"
signal which you feed into the matrix when you go from M/S to L/R.

If you want to get a certain amount of reverberance overall, you can
get it with either setup--but there will be more of a stereo aspect to
the reflected sound energy in the MK 41 setup, since more of it will
be coming from the "S" microphone than it would with the MK 4.

Also, the reverberant energy picked up by a supercardioid will generally
be more diffuse, longer delayed and better blended than with a cardioid,
since a greater proportion of the indirect sound which it does pick up
will arrive through the rear lobe of the supercardioid. Since that
lobe is aimed away from the direct sound source, it will receive sound
that has traveled farther on average than the reflected sound which is
picked up at the sides of a cardioid. Thus the reverberant sound will
have undergone more high-frequency absorption and will be more delayed,
which are both things that help mellow out the reverberant sound and
keep it from messing up the front stereo image.

So in general, I favor using a supercardioid "M" microphone. If I have
to cover so wide an area that I can't use that narrow a pattern, then a
centered, coincident stereo pickup probably isn't the best idea anyway
(unless mono compatibility is an absolute requirement).

--best regards

[David Satz]

Sugarite wrote:

> [A]s the Schoeps website says about the MK8, "directional pattern
> almost completely identical at all frequencies." Every fig-8 mic
> can share the exact same description, because they're all unequal
> front-to-rear, which translates to unequal left-to-right in MS.

The degree of front/back discrepancy in figure-8 microphones varies
from design to design. For example, Royer has two basic models of
ribbon microphone: one for pop and one for classical (more or less).
The "classical" one is highly symmetrical front to back, while the
"pop" one is not so much, and the company is quite open about this.
The "classical" model also has the flatter frequency response of the
two models through the midrange and upper midrange. It would thus
be preferable all around as the "S" microphone for an M/S pair.

I have some special interest in your remarks since I'm the primary
German-to-English translator for Schoeps, and those are my words that
you're quoting. Small response discrepancies do show up between the
front and back lobes of a Schoeps figure-8. But discrepancies of that
magnitude show up when you run the same curve twice in a row without
changing or moving anything, so that should be taken into account, too.

I'm looking at the factory frequency response curves for my own MK 8
capsules, using the same pen and paper speeds that Schoeps' engineers
use for their own research, not some idealized version of the curves
for marketing purposes. (Or OK--I was looking at them a minute ago,
then I put them down because I can't type while holding them, but they
are the real curves.) No discrepancy between front and back is visible
on the chart recorder until you get above, say 3 kHz, where there are
occasional burbles of some fraction of a dB or so--up to maybe one
whole entire dB (horror of horrors!) above 9 kHz.

Given the margin of measurement uncertainty, these are effectively the
same curve to within 1 dB--and below 3 kHz they _are_ the same curve.


> It's still a moot point though, you really need spaced cardioids
> to get the time differential aspect of natural imaging.

That's the direct opposite of what most people in this field believe,
and what several decades of live recording experience tell me.

Whenever you play a recording back through loudspeakers, you get the
same arrival time differences between the listeners' ears as you would
get in the original sound field. You don't need to create arrival time
differences between channels by spacing the microphones unless you're
recording for headphone ("binaural") playback. Otherwise it's an option
if you like the resulting sound, but it's not any kind of necessity.

Spaced microphones pretty much lead to artificial imaging. That can
be nice in moderation, and spaced microphone techniques allow pressure
transducers to be used, which can give a very natural sound in certain
respects--but natural imaging certainly isn't one of those respects.
More often you risk getting "the piano that ate Manhattan," etc.


> Try an ORTF rig before resorting to the only mic whose description
> seems to meet your unorthodox needs.

Huh?

[David Satz]

Sugarite wrote:

> [A]s the Schoeps website says about the MK8, "directional pattern
> almost completely identical at all frequencies." Every fig-8 mic
> can share the exact same description, because they're all unequal
> front-to-rear, which translates to unequal left-to-right in MS.

The degree of front/back discrepancy in figure-8 microphones varies
from design to design. For example, Royer has two basic models of
ribbon microphone: one for pop and one for classical (more or less).
The "classical" one is highly symmetrical front to back, while the
"pop" one is not so much, and the company is quite open about this.
The "classical" model also has the flatter frequency response of the
two models through the midrange and upper midrange. It would thus
be preferable all around as the "S" microphone for an M/S pair.

I have some special interest in your remarks since I'm the primary
German-to-English translator for Schoeps, and those are my words that
you're quoting. Small response discrepancies do show up between the
front and back lobes of a Schoeps figure-8. But discrepancies of that
magnitude show up when you run the same curve twice in a row without
changing or moving anything, so that should be taken into account, too.

I'm looking at the factory frequency response curves for my own MK 8
capsules, using the same pen and paper speeds that Schoeps' engineers
use for their own research, not some idealized version of the curves
for marketing purposes. (Or OK--I was looking at them a minute ago,
then I put them down because I can't type while holding them, but they
are the real curves.) No discrepancy between front and back is visible
on the chart recorder until you get above, say 3 kHz, where there are
occasional burbles of some fraction of a dB or so--up to maybe one
whole entire dB (horror of horrors!) above 9 kHz.

Given the margin of measurement uncertainty, these are effectively the
same curve to within 1 dB--and below 3 kHz they _are_ the same curve.


> It's still a moot point though, you really need spaced cardioids
> to get the time differential aspect of natural imaging.

That's the direct opposite of what most people in this field believe,
and what several decades of live recording experience tell me.

Whenever you play a recording back through loudspeakers, you get the
same arrival time differences between the listeners' ears as you would
get in the original sound field. You don't need to create arrival time
differences between channels by spacing the microphones unless you're
recording for headphone ("binaural") playback. Otherwise it's an option
if you like the resulting sound, but it's not any kind of necessity.

Spaced microphones pretty much lead to artificial imaging. That can
be nice in moderation, and spaced microphone techniques allow pressure
transducers to be used, which can give a very natural sound in certain
respects--but natural imaging certainly isn't one of those respects.
More often you risk getting "the piano that ate Manhattan," etc.


> Try an ORTF rig before resorting to the only mic whose description
> seems to meet your unorthodox needs.

Huh?

[Kurt Albershardt]

Richard Kuschel wrote:
>
> most ribbon figure 8's have the same front and back frequency response
> with the exception of the Royer R-121 which was designed to handle high SPL's
> and this changed the response.

And the AEA R84 (for the same reasons.)

[Kurt Albershardt]

Richard Kuschel wrote:
>
> most ribbon figure 8's have the same front and back frequency response
> with the exception of the Royer R-121 which was designed to handle high SPL's
> and this changed the response.

And the AEA R84 (for the same reasons.)

[Scott Dorsey]

In article >,
Kurt Albershardt > wrote:
>Richard Kuschel wrote:
>>
>> most ribbon figure 8's have the same front and back frequency response
>> with the exception of the Royer R-121 which was designed to handle high SPL's
>> and this changed the response.
>
>And the AEA R84 (for the same reasons.)

Note that the 77DX has very different front and back response as well, when
in figure-8 mode.

In every case, the differing response affects the quality and location of
the null. This is a bad thing in my opinion. The null on a 74B is much
better than on a 77DX.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

In article >,
Kurt Albershardt > wrote:
>Richard Kuschel wrote:
>>
>> most ribbon figure 8's have the same front and back frequency response
>> with the exception of the Royer R-121 which was designed to handle high SPL's
>> and this changed the response.
>
>And the AEA R84 (for the same reasons.)

Note that the 77DX has very different front and back response as well, when
in figure-8 mode.

In every case, the differing response affects the quality and location of
the null. This is a bad thing in my opinion. The null on a 74B is much
better than on a 77DX.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Bob Cain]

Richard Kuschel wrote:
>>However, as the Schoeps website says about the MK8, "directional pattern
>>almost completely identical at all frequencies." Every fig-8 mic can share
>>the exact same description, because they're all unequal front-to-rear, which
>>translates to unequal left-to-right in MS.
>>
>
>
> Why would that be?
> If using a single diaphragm figute 8 (Schoeps, Sennheiser and Neumann) wouldn't
> the response be the same front to back.

They aren't usually mechanically symmetric front and back.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Richard Kuschel wrote:
>>However, as the Schoeps website says about the MK8, "directional pattern
>>almost completely identical at all frequencies." Every fig-8 mic can share
>>the exact same description, because they're all unequal front-to-rear, which
>>translates to unequal left-to-right in MS.
>>
>
>
> Why would that be?
> If using a single diaphragm figute 8 (Schoeps, Sennheiser and Neumann) wouldn't
> the response be the same front to back.

They aren't usually mechanically symmetric front and back.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

David Satz wrote:

> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

That _is_ symmetric for all practical purposes. But you
knew that. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

David Satz wrote:

> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

That _is_ symmetric for all practical purposes. But you
knew that. :-)


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

David Satz wrote:

> So in general, I favor using a supercardioid "M" microphone. If I have
> to cover so wide an area that I can't use that narrow a pattern, then a
> centered, coincident stereo pickup probably isn't the best idea anyway
> (unless mono compatibility is an absolute requirement).

If you think of the cardiod family M as a figure 8 summed
with an omni and if you match the gain of the figure 8
component with that of the side, then the sum and difference
that do the MS -> LR encoding just create a left figure 8
pointing at -45 and a right figure 8 pointing at +45 both
superimposed with the omni component of the M mic. The
ratio of that omni component to the figure 8 is what
determines where in the cardiod spectrum the real mic and
virtual LR mics fit (hyper, super, card, sub, hypo.)

If the fig 8 sensitivities are matched between mid and side
and the M is a true card then the +-45 degree virtual LR
mics will be hyper cardiod because their fig 8 components
will have sensitivities that are the sqrt(2) times that of
the actual mics while the omni component is one times the
omni component of the mid. Thus, going somewhat
hypercardiod with the mid, as you suggest, makes the virtual
LR mics even more hypercardiod.

In practice, the M and S sensitivities are nowhere near as
carefully controled if one is setting one's own relative MS
gains and it is virtually impossible to say what virtual LR
patterns you have. For that reason, you experiment, listen
and tweak. :-)

If you further take into consideration that these patterns
are highly frequency dependant, even if symmetric front to
back, then it is _very_ hard to generalize what you get from
a coincident (intensity based) stereo configuration, MS or
XY. That's not to say, however, that they can't sound great.

One thing I have not been able to get away from with MS or
XY is that if I have a drum kit that is a fair bit to the
side then the image separation between the kick and cymbal
is very highly exagerated and the cymbal can even swap
sides. This is because of the frequency dependant patterns
and because phase matching becomes very important at the
higher frequencies due to the MS->LR summing.

The more I study this stuff the more I come to realize that
there really isn't a theoretical basis for stereo
configurations that holds any water because all the premises
of the theories are idealizations that are terribly far from
reality. It's all hueristic in the end. Try things without
much worrying about what is right or wrong and see what you get.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

David Satz wrote:

> So in general, I favor using a supercardioid "M" microphone. If I have
> to cover so wide an area that I can't use that narrow a pattern, then a
> centered, coincident stereo pickup probably isn't the best idea anyway
> (unless mono compatibility is an absolute requirement).

If you think of the cardiod family M as a figure 8 summed
with an omni and if you match the gain of the figure 8
component with that of the side, then the sum and difference
that do the MS -> LR encoding just create a left figure 8
pointing at -45 and a right figure 8 pointing at +45 both
superimposed with the omni component of the M mic. The
ratio of that omni component to the figure 8 is what
determines where in the cardiod spectrum the real mic and
virtual LR mics fit (hyper, super, card, sub, hypo.)

If the fig 8 sensitivities are matched between mid and side
and the M is a true card then the +-45 degree virtual LR
mics will be hyper cardiod because their fig 8 components
will have sensitivities that are the sqrt(2) times that of
the actual mics while the omni component is one times the
omni component of the mid. Thus, going somewhat
hypercardiod with the mid, as you suggest, makes the virtual
LR mics even more hypercardiod.

In practice, the M and S sensitivities are nowhere near as
carefully controled if one is setting one's own relative MS
gains and it is virtually impossible to say what virtual LR
patterns you have. For that reason, you experiment, listen
and tweak. :-)

If you further take into consideration that these patterns
are highly frequency dependant, even if symmetric front to
back, then it is _very_ hard to generalize what you get from
a coincident (intensity based) stereo configuration, MS or
XY. That's not to say, however, that they can't sound great.

One thing I have not been able to get away from with MS or
XY is that if I have a drum kit that is a fair bit to the
side then the image separation between the kick and cymbal
is very highly exagerated and the cymbal can even swap
sides. This is because of the frequency dependant patterns
and because phase matching becomes very important at the
higher frequencies due to the MS->LR summing.

The more I study this stuff the more I come to realize that
there really isn't a theoretical basis for stereo
configurations that holds any water because all the premises
of the theories are idealizations that are terribly far from
reality. It's all hueristic in the end. Try things without
much worrying about what is right or wrong and see what you get.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Sugarite]

> > It's still a moot point though, you really need spaced cardioids to get
the
> > time differential aspect of natural imaging.
>
> I strongly disagree. Coincident, intensity based methods
> are in wide and sucessful use. It's a matter of taste.
>
> The time differential that is recorded gets so munged by the
> time domain mangling that speakers and rooms effect that on
> reproduction it in no way resembles what was recorded.

I agree, it is a matter of taste. For example, you could take that whole
response and replace time differential issues with intensity issues, still
100% true.

There are times to say "people's stereos suck" and make comprimises, but IMO
distant micing with spaced mics for acoustic instruments never does more
harm than good if done right.

[Sugarite]

> > It's still a moot point though, you really need spaced cardioids to get
the
> > time differential aspect of natural imaging.
>
> I strongly disagree. Coincident, intensity based methods
> are in wide and sucessful use. It's a matter of taste.
>
> The time differential that is recorded gets so munged by the
> time domain mangling that speakers and rooms effect that on
> reproduction it in no way resembles what was recorded.

I agree, it is a matter of taste. For example, you could take that whole
response and replace time differential issues with intensity issues, still
100% true.

There are times to say "people's stereos suck" and make comprimises, but IMO
distant micing with spaced mics for acoustic instruments never does more
harm than good if done right.

[Sugarite]

> > [A]s the Schoeps website says about the MK8, "directional pattern
> > almost completely identical at all frequencies." Every fig-8 mic
> > can share the exact same description, because they're all unequal
> > front-to-rear, which translates to unequal left-to-right in MS.
>
> The degree of front/back discrepancy in figure-8 microphones varies
> from design to design. For example, Royer has two basic models of
> ribbon microphone: one for pop and one for classical (more or less).
> The "classical" one is highly symmetrical front to back, while the
> "pop" one is not so much, and the company is quite open about this.
> The "classical" model also has the flatter frequency response of the
> two models through the midrange and upper midrange. It would thus
> be preferable all around as the "S" microphone for an M/S pair.
>
> I have some special interest in your remarks since I'm the primary
> German-to-English translator for Schoeps, and those are my words that
> you're quoting. Small response discrepancies do show up between the
> front and back lobes of a Schoeps figure-8. But discrepancies of that
> magnitude show up when you run the same curve twice in a row without
> changing or moving anything, so that should be taken into account, too.
>
> I'm looking at the factory frequency response curves for my own MK 8
> capsules, using the same pen and paper speeds that Schoeps' engineers
> use for their own research, not some idealized version of the curves
> for marketing purposes. (Or OK--I was looking at them a minute ago,
> then I put them down because I can't type while holding them, but they
> are the real curves.) No discrepancy between front and back is visible
> on the chart recorder until you get above, say 3 kHz, where there are
> occasional burbles of some fraction of a dB or so--up to maybe one
> whole entire dB (horror of horrors!) above 9 kHz.
>
> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

This is leading towards a debate over whether two matched cardioids are in
fact a truer match than either side of a fig-8. I'm of the opinion that the
matched card's are a truer match, mostly because you can't as easily test
the internal bipolar matching on a mic-by-mic basis like matching two
card's. In particular, when two card's achieve a null result under
opposition, they can be trusted to be matched in both mechanics and
electronics with extreme precision. It's impossible to test both sides of a
fig-8 with that level of precision. All you can do is "read curves".

> > It's still a moot point though, you really need spaced cardioids
> > to get the time differential aspect of natural imaging.
>
> That's the direct opposite of what most people in this field believe,
> and what several decades of live recording experience tell me.
>
> Whenever you play a recording back through loudspeakers, you get the
> same arrival time differences between the listeners' ears as you would
> get in the original sound field. You don't need to create arrival time
> differences between channels by spacing the microphones unless you're
> recording for headphone ("binaural") playback. Otherwise it's an option
> if you like the resulting sound, but it's not any kind of necessity.

I certainly hope that's not what most people in this field believe. You do
get time differentials from the separation of loudspeakers, but it's hardly
"one size fits all". To say spaced mic techniques are only appropriate for
binaural playback is as obtuse as saying coincident mic techniques are only
good for separated loudspeaker playback.

In particular, spaced mics can offer a sense of space that coincident mics
can't, since lateral sounds, in particular room ambience, result in greater
time differentials, producing a greater sense of width without comprimising
the coverage of the center signals, which for coincident mics means sending
the center signals further off-axis or widening the stereo recording in
mix/post.

There are times to add space between mics, times to widen the angle between
coincident mics, and times to narrow the angle and widen in post. Distant
micing of acoustic instruments generally means adding space IME. When a
sound reinforcement system is involved, coincident mics are imperative,
since spacing the mics generates very unnatural correlated differentials
from the separated sound sources putting out the same signal. When you have
a broad ensemble of acoustic sources, you end up somewhere in between.

I'm somewhat surprised at your opinion. Normally I'm trying to tell tapers
not to use spaced mics for concerts with PA's...

[Sugarite]

> > [A]s the Schoeps website says about the MK8, "directional pattern
> > almost completely identical at all frequencies." Every fig-8 mic
> > can share the exact same description, because they're all unequal
> > front-to-rear, which translates to unequal left-to-right in MS.
>
> The degree of front/back discrepancy in figure-8 microphones varies
> from design to design. For example, Royer has two basic models of
> ribbon microphone: one for pop and one for classical (more or less).
> The "classical" one is highly symmetrical front to back, while the
> "pop" one is not so much, and the company is quite open about this.
> The "classical" model also has the flatter frequency response of the
> two models through the midrange and upper midrange. It would thus
> be preferable all around as the "S" microphone for an M/S pair.
>
> I have some special interest in your remarks since I'm the primary
> German-to-English translator for Schoeps, and those are my words that
> you're quoting. Small response discrepancies do show up between the
> front and back lobes of a Schoeps figure-8. But discrepancies of that
> magnitude show up when you run the same curve twice in a row without
> changing or moving anything, so that should be taken into account, too.
>
> I'm looking at the factory frequency response curves for my own MK 8
> capsules, using the same pen and paper speeds that Schoeps' engineers
> use for their own research, not some idealized version of the curves
> for marketing purposes. (Or OK--I was looking at them a minute ago,
> then I put them down because I can't type while holding them, but they
> are the real curves.) No discrepancy between front and back is visible
> on the chart recorder until you get above, say 3 kHz, where there are
> occasional burbles of some fraction of a dB or so--up to maybe one
> whole entire dB (horror of horrors!) above 9 kHz.
>
> Given the margin of measurement uncertainty, these are effectively the
> same curve to within 1 dB--and below 3 kHz they _are_ the same curve.

This is leading towards a debate over whether two matched cardioids are in
fact a truer match than either side of a fig-8. I'm of the opinion that the
matched card's are a truer match, mostly because you can't as easily test
the internal bipolar matching on a mic-by-mic basis like matching two
card's. In particular, when two card's achieve a null result under
opposition, they can be trusted to be matched in both mechanics and
electronics with extreme precision. It's impossible to test both sides of a
fig-8 with that level of precision. All you can do is "read curves".

> > It's still a moot point though, you really need spaced cardioids
> > to get the time differential aspect of natural imaging.
>
> That's the direct opposite of what most people in this field believe,
> and what several decades of live recording experience tell me.
>
> Whenever you play a recording back through loudspeakers, you get the
> same arrival time differences between the listeners' ears as you would
> get in the original sound field. You don't need to create arrival time
> differences between channels by spacing the microphones unless you're
> recording for headphone ("binaural") playback. Otherwise it's an option
> if you like the resulting sound, but it's not any kind of necessity.

I certainly hope that's not what most people in this field believe. You do
get time differentials from the separation of loudspeakers, but it's hardly
"one size fits all". To say spaced mic techniques are only appropriate for
binaural playback is as obtuse as saying coincident mic techniques are only
good for separated loudspeaker playback.

In particular, spaced mics can offer a sense of space that coincident mics
can't, since lateral sounds, in particular room ambience, result in greater
time differentials, producing a greater sense of width without comprimising
the coverage of the center signals, which for coincident mics means sending
the center signals further off-axis or widening the stereo recording in
mix/post.

There are times to add space between mics, times to widen the angle between
coincident mics, and times to narrow the angle and widen in post. Distant
micing of acoustic instruments generally means adding space IME. When a
sound reinforcement system is involved, coincident mics are imperative,
since spacing the mics generates very unnatural correlated differentials
from the separated sound sources putting out the same signal. When you have
a broad ensemble of acoustic sources, you end up somewhere in between.

I'm somewhat surprised at your opinion. Normally I'm trying to tell tapers
not to use spaced mics for concerts with PA's...

[Bob Cain]

Sugarite wrote:

> There are times to say "people's stereos suck" and make comprimises, but IMO
> distant micing with spaced mics for acoustic instruments never does more
> harm than good if done right.

I need to do more work with spaced omni's. The deeper I
investigate the operation of coincident methods the more I
see that they are fraught with difficulties due to angular
variations in frequency response (magnitude and phase.)
They aren't just theoretical either, I can hear them. I've
been at a loss for some time to understand why the cymbals
from a drumset would be so far removed from the kick thump
in an MS recording when they aren't physically removed much
at all but the reasons for that are becoming clearer.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:

> There are times to say "people's stereos suck" and make comprimises, but IMO
> distant micing with spaced mics for acoustic instruments never does more
> harm than good if done right.

I need to do more work with spaced omni's. The deeper I
investigate the operation of coincident methods the more I
see that they are fraught with difficulties due to angular
variations in frequency response (magnitude and phase.)
They aren't just theoretical either, I can hear them. I've
been at a loss for some time to understand why the cymbals
from a drumset would be so far removed from the kick thump
in an MS recording when they aren't physically removed much
at all but the reasons for that are becoming clearer.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:
> When a
> sound reinforcement system is involved, coincident mics are imperative,
> since spacing the mics generates very unnatural correlated differentials
> from the separated sound sources putting out the same signal. When you have
> a broad ensemble of acoustic sources, you end up somewhere in between.

But why would one be doing stereo with sound reinforcement?
The few times I've tried it the variation due to position
in the audience has made it useless unless you are really
close to center and even then it just doesn't come out right.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Sugarite wrote:
> When a
> sound reinforcement system is involved, coincident mics are imperative,
> since spacing the mics generates very unnatural correlated differentials
> from the separated sound sources putting out the same signal. When you have
> a broad ensemble of acoustic sources, you end up somewhere in between.

But why would one be doing stereo with sound reinforcement?
The few times I've tried it the variation due to position
in the audience has made it useless unless you are really
close to center and even then it just doesn't come out right.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Scott Dorsey]

Bob Cain > wrote:
>Sugarite wrote:
>> When a
>> sound reinforcement system is involved, coincident mics are imperative,
>> since spacing the mics generates very unnatural correlated differentials
>> from the separated sound sources putting out the same signal. When you have
>> a broad ensemble of acoustic sources, you end up somewhere in between.
>
>But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
>in the audience has made it useless unless you are really
>close to center and even then it just doesn't come out right.

It depends a lot on the room. In a narrow and long room that isn't too
bright, you can do a surprisingly good job of getting a real stereo image,
even on the sides. You may need mono front fills in order to deal with
the first couple rows on the side, though.

Also, a center cluster can do an amazing job of making stereo work in a
room where it otherwise wouldn't. It won't do miracles, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Bob Cain > wrote:
>Sugarite wrote:
>> When a
>> sound reinforcement system is involved, coincident mics are imperative,
>> since spacing the mics generates very unnatural correlated differentials
>> from the separated sound sources putting out the same signal. When you have
>> a broad ensemble of acoustic sources, you end up somewhere in between.
>
>But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
>in the audience has made it useless unless you are really
>close to center and even then it just doesn't come out right.

It depends a lot on the room. In a narrow and long room that isn't too
bright, you can do a surprisingly good job of getting a real stereo image,
even on the sides. You may need mono front fills in order to deal with
the first couple rows on the side, though.

Also, a center cluster can do an amazing job of making stereo work in a
room where it otherwise wouldn't. It won't do miracles, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[David Satz]

Bob Cain wrote:

> Using three identical capsules, one for the front and two
> for the side and reasonably matched is pretty near optimal
> for M/S IMO.

Bob, as you know I've posted some messages here saying that matching
the sonic character of the M and S mikes is not a particular virtue,
and that a flat/smooth/accurate characteristic for S matters far more.

Then you sent me your more detailed thoughts off-list, which gave me a
chance to rethink this issue. I have to admit that there's more to it
than I thought before (i.e. there may be something to it at all).

Here's how I would express it non-mathematically. The issue is how
the stereo image will be affected by the response characteristics of
the two microphones after the M/S signals have been matrixed to L/R.

If the M microphone emphasizes certain sound components (e.g. the high
frequencies) while the S microphone doesn't, then in the eventual L/R
stereo output of the matrix, those components will tend to gather at
the image's center more than the midrange sound does. The apparent
left-right position of any given instrument or voice would thus be
blurred. Conversely, if the S microphone boosts the highs while the
M microphone doesn't, high frequency energy would tend to be shifted
more toward the left and right than the midrange sound--increasingly
so with individual voices or instruments that are already off-center.

Both effects are undesirable, but they do work in generally opposing
directions--either one would tend to compensate for the other to some
degree. So I think I see the intended point of "matching" the general
sonic characteristics of the M and S microphones now. I don't endorse
it completely, but I see a possible rational hope behind it at least.

It will take me another little while to say where I don't agree; the
main issue is the fact that most microphones (except for the best
small-diaphragm figure-8s and certain rather noisy omnis) don't have
the same frequency response at all angles of incidence. So all our
"virtual microphones" have rather complex, irregular response--that's
another reason I tend to favor a super- or hypercardioid for "M".

However, I'll also point out that the analog of using a non-flat S mike
is processing the S channel independently of the M channel--and there is
a long tradition of doing exactly that. One of the attractions of M/S
(whether the recording is made originally that way, or whether another
type of X/Y recording is matrixed to M/S) is that the M and S channels
can be equalized independently or processed in other ways independently,
then rematrixed to L/R stereo.

For example, LP disc cutters would often matrix a stereo signal to sum
and difference channels (equivalent to M and S), and limit the difference
channel and/or roll off its low-frequency energy, since the difference
energy corresponds essentially to the vertical component of the groove
to be cut, while the M channel corresponds to its horizontal component.
Excessive vertical modulation could cause skipping, and would tend to
limit the playing time of the side and the maximum modulation of the
groove--which in turn would limit the playback volume and the signal-
to-noise ratio. Cutting the loudest possible record was an obsession
with LP mastering engineers, too--not something that snuck into the
business with the diabolical introduction of digital recording.

This also addresses a point made by "Sugarite"--he's right that X/Y
(coincident) recordings often lack a sense of spaciousness, and that
spaced microphone recordings are sometimes preferred for that reason.
But one other way to increase the sense of spaciousness, or at least
to help compensate for some of the relative lack of it, is to boost
the low-frequency response of the "S" channel.

If anyone remembers Bob Carver's "Digital Time Lens" processor--a
surprisingly useful general-purpose "feel-good box" that doesn't add
distortion--that's one of the tricks he was using in that circuit.

[David Satz]

Bob Cain wrote:

> Using three identical capsules, one for the front and two
> for the side and reasonably matched is pretty near optimal
> for M/S IMO.

Bob, as you know I've posted some messages here saying that matching
the sonic character of the M and S mikes is not a particular virtue,
and that a flat/smooth/accurate characteristic for S matters far more.

Then you sent me your more detailed thoughts off-list, which gave me a
chance to rethink this issue. I have to admit that there's more to it
than I thought before (i.e. there may be something to it at all).

Here's how I would express it non-mathematically. The issue is how
the stereo image will be affected by the response characteristics of
the two microphones after the M/S signals have been matrixed to L/R.

If the M microphone emphasizes certain sound components (e.g. the high
frequencies) while the S microphone doesn't, then in the eventual L/R
stereo output of the matrix, those components will tend to gather at
the image's center more than the midrange sound does. The apparent
left-right position of any given instrument or voice would thus be
blurred. Conversely, if the S microphone boosts the highs while the
M microphone doesn't, high frequency energy would tend to be shifted
more toward the left and right than the midrange sound--increasingly
so with individual voices or instruments that are already off-center.

Both effects are undesirable, but they do work in generally opposing
directions--either one would tend to compensate for the other to some
degree. So I think I see the intended point of "matching" the general
sonic characteristics of the M and S microphones now. I don't endorse
it completely, but I see a possible rational hope behind it at least.

It will take me another little while to say where I don't agree; the
main issue is the fact that most microphones (except for the best
small-diaphragm figure-8s and certain rather noisy omnis) don't have
the same frequency response at all angles of incidence. So all our
"virtual microphones" have rather complex, irregular response--that's
another reason I tend to favor a super- or hypercardioid for "M".

However, I'll also point out that the analog of using a non-flat S mike
is processing the S channel independently of the M channel--and there is
a long tradition of doing exactly that. One of the attractions of M/S
(whether the recording is made originally that way, or whether another
type of X/Y recording is matrixed to M/S) is that the M and S channels
can be equalized independently or processed in other ways independently,
then rematrixed to L/R stereo.

For example, LP disc cutters would often matrix a stereo signal to sum
and difference channels (equivalent to M and S), and limit the difference
channel and/or roll off its low-frequency energy, since the difference
energy corresponds essentially to the vertical component of the groove
to be cut, while the M channel corresponds to its horizontal component.
Excessive vertical modulation could cause skipping, and would tend to
limit the playing time of the side and the maximum modulation of the
groove--which in turn would limit the playback volume and the signal-
to-noise ratio. Cutting the loudest possible record was an obsession
with LP mastering engineers, too--not something that snuck into the
business with the diabolical introduction of digital recording.

This also addresses a point made by "Sugarite"--he's right that X/Y
(coincident) recordings often lack a sense of spaciousness, and that
spaced microphone recordings are sometimes preferred for that reason.
But one other way to increase the sense of spaciousness, or at least
to help compensate for some of the relative lack of it, is to boost
the low-frequency response of the "S" channel.

If anyone remembers Bob Carver's "Digital Time Lens" processor--a
surprisingly useful general-purpose "feel-good box" that doesn't add
distortion--that's one of the tricks he was using in that circuit.

[locosoundman]

Great thread - thanks for all of the information everyone.

In general I go with ORTF or some near-coincident variant therof but I
like to use spaced-pair techniques on large ensembles when the room
permits, or if I am using two stereo pairs in conjunction - one to
accent something like a choir, in which case I use a coincident pair
on the accent to get a strong center and clear localisation to better
blend with the diffuse image of the spaced pair - usually a nice
effect. I prefer to use coicindent methods simply for the effect of a
narrower image with a strong center, to be able to control the width
of the image later without phase problems, or for sound that will end
up on video.

I have heard much about the supposed advantage of MS over XY because
of the ability to control stereo width after the fact, but I have
never used it due to the complications of rigging it. Usually my
recordings are done live in concert, so aesthetics are a concern, but
for a recording session coming up soon (a jazz trio), I was
considering combining a spaced pair in conjunction with a coincident
pair for drums and piano. I am considering MS because aesthetics are
not a consideration in this case. Investing in a Schoeps CMC6 MK8
combo is not out of the question, but as I have not often used MS, I
would rather utilise that chunk of my equipment budget in other ways.

I would specifically like to ask David Satz a question about the
Schoeps MK8 capsule due to his familiarity, of course anyone can
respond: I have seen the response charts of the MK8, and I recall that
the drop-off in the bass and the high end were rather severe, but I
know enough to take these charts with a grain of salt. Has it been
your experience that the "accuracy" of sound reproduction was
adversely affected by this?


Bob Cain > wrote in message >...
> David Satz wrote:
>
> > So in general, I favor using a supercardioid "M" microphone. If I have
> > to cover so wide an area that I can't use that narrow a pattern, then a
> > centered, coincident stereo pickup probably isn't the best idea anyway
> > (unless mono compatibility is an absolute requirement).
>
> If you think of the cardiod family M as a figure 8 summed
> with an omni and if you match the gain of the figure 8
> component with that of the side, then the sum and difference
> that do the MS -> LR encoding just create a left figure 8
> pointing at -45 and a right figure 8 pointing at +45 both
> superimposed with the omni component of the M mic. The
> ratio of that omni component to the figure 8 is what
> determines where in the cardiod spectrum the real mic and
> virtual LR mics fit (hyper, super, card, sub, hypo.)
>
> If the fig 8 sensitivities are matched between mid and side
> and the M is a true card then the +-45 degree virtual LR
> mics will be hyper cardiod because their fig 8 components
> will have sensitivities that are the sqrt(2) times that of
> the actual mics while the omni component is one times the
> omni component of the mid. Thus, going somewhat
> hypercardiod with the mid, as you suggest, makes the virtual
> LR mics even more hypercardiod.
>
> In practice, the M and S sensitivities are nowhere near as
> carefully controled if one is setting one's own relative MS
> gains and it is virtually impossible to say what virtual LR
> patterns you have. For that reason, you experiment, listen
> and tweak. :-)
>
> If you further take into consideration that these patterns
> are highly frequency dependant, even if symmetric front to
> back, then it is _very_ hard to generalize what you get from
> a coincident (intensity based) stereo configuration, MS or
> XY. That's not to say, however, that they can't sound great.
>
> One thing I have not been able to get away from with MS or
> XY is that if I have a drum kit that is a fair bit to the
> side then the image separation between the kick and cymbal
> is very highly exagerated and the cymbal can even swap
> sides. This is because of the frequency dependant patterns
> and because phase matching becomes very important at the
> higher frequencies due to the MS->LR summing.
>
> The more I study this stuff the more I come to realize that
> there really isn't a theoretical basis for stereo
> configurations that holds any water because all the premises
> of the theories are idealizations that are terribly far from
> reality. It's all hueristic in the end. Try things without
> much worrying about what is right or wrong and see what you get.
>
>
> Bob

[locosoundman]

Great thread - thanks for all of the information everyone.

In general I go with ORTF or some near-coincident variant therof but I
like to use spaced-pair techniques on large ensembles when the room
permits, or if I am using two stereo pairs in conjunction - one to
accent something like a choir, in which case I use a coincident pair
on the accent to get a strong center and clear localisation to better
blend with the diffuse image of the spaced pair - usually a nice
effect. I prefer to use coicindent methods simply for the effect of a
narrower image with a strong center, to be able to control the width
of the image later without phase problems, or for sound that will end
up on video.

I have heard much about the supposed advantage of MS over XY because
of the ability to control stereo width after the fact, but I have
never used it due to the complications of rigging it. Usually my
recordings are done live in concert, so aesthetics are a concern, but
for a recording session coming up soon (a jazz trio), I was
considering combining a spaced pair in conjunction with a coincident
pair for drums and piano. I am considering MS because aesthetics are
not a consideration in this case. Investing in a Schoeps CMC6 MK8
combo is not out of the question, but as I have not often used MS, I
would rather utilise that chunk of my equipment budget in other ways.

I would specifically like to ask David Satz a question about the
Schoeps MK8 capsule due to his familiarity, of course anyone can
respond: I have seen the response charts of the MK8, and I recall that
the drop-off in the bass and the high end were rather severe, but I
know enough to take these charts with a grain of salt. Has it been
your experience that the "accuracy" of sound reproduction was
adversely affected by this?


Bob Cain > wrote in message >...
> David Satz wrote:
>
> > So in general, I favor using a supercardioid "M" microphone. If I have
> > to cover so wide an area that I can't use that narrow a pattern, then a
> > centered, coincident stereo pickup probably isn't the best idea anyway
> > (unless mono compatibility is an absolute requirement).
>
> If you think of the cardiod family M as a figure 8 summed
> with an omni and if you match the gain of the figure 8
> component with that of the side, then the sum and difference
> that do the MS -> LR encoding just create a left figure 8
> pointing at -45 and a right figure 8 pointing at +45 both
> superimposed with the omni component of the M mic. The
> ratio of that omni component to the figure 8 is what
> determines where in the cardiod spectrum the real mic and
> virtual LR mics fit (hyper, super, card, sub, hypo.)
>
> If the fig 8 sensitivities are matched between mid and side
> and the M is a true card then the +-45 degree virtual LR
> mics will be hyper cardiod because their fig 8 components
> will have sensitivities that are the sqrt(2) times that of
> the actual mics while the omni component is one times the
> omni component of the mid. Thus, going somewhat
> hypercardiod with the mid, as you suggest, makes the virtual
> LR mics even more hypercardiod.
>
> In practice, the M and S sensitivities are nowhere near as
> carefully controled if one is setting one's own relative MS
> gains and it is virtually impossible to say what virtual LR
> patterns you have. For that reason, you experiment, listen
> and tweak. :-)
>
> If you further take into consideration that these patterns
> are highly frequency dependant, even if symmetric front to
> back, then it is _very_ hard to generalize what you get from
> a coincident (intensity based) stereo configuration, MS or
> XY. That's not to say, however, that they can't sound great.
>
> One thing I have not been able to get away from with MS or
> XY is that if I have a drum kit that is a fair bit to the
> side then the image separation between the kick and cymbal
> is very highly exagerated and the cymbal can even swap
> sides. This is because of the frequency dependant patterns
> and because phase matching becomes very important at the
> higher frequencies due to the MS->LR summing.
>
> The more I study this stuff the more I come to realize that
> there really isn't a theoretical basis for stereo
> configurations that holds any water because all the premises
> of the theories are idealizations that are terribly far from
> reality. It's all hueristic in the end. Try things without
> much worrying about what is right or wrong and see what you get.
>
>
> Bob

[David Satz]

Eric K. Weber wrote:

> The following small diaphram solutions do exist....
>
> Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
> http://www.sennheiser.com/sennheiser/icm.nsf/root/03109
>
> Schoeps also has small diaphragm figure 8..
> http://www.schoeps.de/E-2004/figure-8.html
> http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

It's significant that these are not only small-diapragm designs but also
_single-diaphragm_ designs. And let's not forget the Neumann KM 120:

http://www.neumann.com/infopool/mics/produkte.php?ProdID=km100

Oddly I've never heard from anyone who has ever used it--and I've
asked around repeatedly. Here goes again: If anyone here has used
this microphone, could you please comment on its sound? I sometimes
use spaced (!) figure-8s for stereo vocal recording, and can imagine
that a response characteristic as shown in Neumann's diagrams might
be useful for that application, or at least worth trying.

_Dual-diaphragm_ small-diaphragm mikes with a selectable figure-8
pattern would include the Neumann KM 56, KM 88 and KM 86. I've used
KM 86s and KM 88s as figure-8 microphones and preferred the KM 88; the
KM 86 is very bright, even harsh off axis when used as a figure-8.

But I chickened out and sold my KM 88s this past year. One accident
with their fragile nickel membranes and poof, it's all over--no original
replacement capsules are available any more, and I'm not interested in
"reskinned" capsules.

[David Satz]

Eric K. Weber wrote:

> The following small diaphram solutions do exist....
>
> Sennheiser MKH30 fig-8 MKH40 card or MKH50 hypercard
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02872
> http://www.sennheiser.com/sennheiser/icm.nsf/root/02645
> http://www.sennheiser.com/sennheiser/icm.nsf/root/03109
>
> Schoeps also has small diaphragm figure 8..
> http://www.schoeps.de/E-2004/figure-8.html
> http://www.schoeps.de/E-2004/ms-stereo.html#msoutdoor

It's significant that these are not only small-diapragm designs but also
_single-diaphragm_ designs. And let's not forget the Neumann KM 120:

http://www.neumann.com/infopool/mics/produkte.php?ProdID=km100

Oddly I've never heard from anyone who has ever used it--and I've
asked around repeatedly. Here goes again: If anyone here has used
this microphone, could you please comment on its sound? I sometimes
use spaced (!) figure-8s for stereo vocal recording, and can imagine
that a response characteristic as shown in Neumann's diagrams might
be useful for that application, or at least worth trying.

_Dual-diaphragm_ small-diaphragm mikes with a selectable figure-8
pattern would include the Neumann KM 56, KM 88 and KM 86. I've used
KM 86s and KM 88s as figure-8 microphones and preferred the KM 88; the
KM 86 is very bright, even harsh off axis when used as a figure-8.

But I chickened out and sold my KM 88s this past year. One accident
with their fragile nickel membranes and poof, it's all over--no original
replacement capsules are available any more, and I'm not interested in
"reskinned" capsules.

[Sugarite]

> > When a
> > sound reinforcement system is involved, coincident mics are imperative,
> > since spacing the mics generates very unnatural correlated differentials
> > from the separated sound sources putting out the same signal. When you
have
> > a broad ensemble of acoustic sources, you end up somewhere in between.
>
> But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
> in the audience has made it useless unless you are really
> close to center and even then it just doesn't come out right.

"Close to the center" indeed, within a few mm of exactly dead center so each
speaker is equidistant. Even with a mono mix, I've gotten vivid stereo
results with a Rode NT4 in a rear position, widening the crap out of it in
post. Widening such a narrow field of direct sound to offer some off-center
detail from stage bleed, the room ambience is wrapped all around. What you
end up with is the best of both worlds - the PA detail of a rear position
and the impact and imaging of the front row. You really have to nail the
mic position though, and any time differentials from mic spacing are
unacceptable, even the dual card's in the typical SDC fig-8. The slightest
inequity in the front/back response of a single diaphram fig-8 would be
grossly evident as well.

For that particular purpose the NT4 is the go-to mic. For loud shows you
can pop a 9V in the chassis and use the included minijack cable directly
into the line input of a NJB3, and for ~$600 total the results are
freakishly good.

[Sugarite]

> > When a
> > sound reinforcement system is involved, coincident mics are imperative,
> > since spacing the mics generates very unnatural correlated differentials
> > from the separated sound sources putting out the same signal. When you
have
> > a broad ensemble of acoustic sources, you end up somewhere in between.
>
> But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
> in the audience has made it useless unless you are really
> close to center and even then it just doesn't come out right.

"Close to the center" indeed, within a few mm of exactly dead center so each
speaker is equidistant. Even with a mono mix, I've gotten vivid stereo
results with a Rode NT4 in a rear position, widening the crap out of it in
post. Widening such a narrow field of direct sound to offer some off-center
detail from stage bleed, the room ambience is wrapped all around. What you
end up with is the best of both worlds - the PA detail of a rear position
and the impact and imaging of the front row. You really have to nail the
mic position though, and any time differentials from mic spacing are
unacceptable, even the dual card's in the typical SDC fig-8. The slightest
inequity in the front/back response of a single diaphram fig-8 would be
grossly evident as well.

For that particular purpose the NT4 is the go-to mic. For loud shows you
can pop a 9V in the chassis and use the included minijack cable directly
into the line input of a NJB3, and for ~$600 total the results are
freakishly good.

[Bob Cain]

David Satz wrote:

> If the M microphone emphasizes certain sound components (e.g. the high
> frequencies) while the S microphone doesn't, then in the eventual L/R
> stereo output of the matrix, those components will tend to gather at
> the image's center more than the midrange sound does. The apparent
> left-right position of any given instrument or voice would thus be
> blurred. Conversely, if the S microphone boosts the highs while the
> M microphone doesn't, high frequency energy would tend to be shifted
> more toward the left and right than the midrange sound--increasingly
> so with individual voices or instruments that are already off-center.

Yes. But even if they are matched blurring will occur
because frequency response is angle dependant or inversely,
the polar plot is frequency dependant. The consequence is
that the virtual mics given by the vector sum of the real
mics have axes that move about with frequency.

> It will take me another little while to say where I don't agree; the
> main issue is the fact that most microphones (except for the best
> small-diaphragm figure-8s and certain rather noisy omnis) don't have
> the same frequency response at all angles of incidence. So all our
> "virtual microphones" have rather complex, irregular response--that's
> another reason I tend to favor a super- or hypercardioid for "M".

I hadn't read ahead. You clearly understand the point I
made above.

>
> However, I'll also point out that the analog of using a non-flat S mike
> is processing the S channel independently of the M channel--and there is
> a long tradition of doing exactly that. One of the attractions of M/S
> (whether the recording is made originally that way, or whether another
> type of X/Y recording is matrixed to M/S) is that the M and S channels
> can be equalized independently or processed in other ways independently,
> then rematrixed to L/R stereo.

You want to make sure that any such manipulation that is
frequency dependant be done with linear phase filters and
that the channel not processed always be delayed by the
group delay of the filter to keep the two channels time
coherent. Changing the relative phase of M and S outputs
also has a large effect on source placement within the image.

All of this having to do with frequency dependant polar
responses and the consequence on imaging applies as well to
the XY configuration. At one extreme, look at the
frequencies where the polar plot gets close to round and all
those frequencies will be moved to the center of the image.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

David Satz wrote:

> If the M microphone emphasizes certain sound components (e.g. the high
> frequencies) while the S microphone doesn't, then in the eventual L/R
> stereo output of the matrix, those components will tend to gather at
> the image's center more than the midrange sound does. The apparent
> left-right position of any given instrument or voice would thus be
> blurred. Conversely, if the S microphone boosts the highs while the
> M microphone doesn't, high frequency energy would tend to be shifted
> more toward the left and right than the midrange sound--increasingly
> so with individual voices or instruments that are already off-center.

Yes. But even if they are matched blurring will occur
because frequency response is angle dependant or inversely,
the polar plot is frequency dependant. The consequence is
that the virtual mics given by the vector sum of the real
mics have axes that move about with frequency.

> It will take me another little while to say where I don't agree; the
> main issue is the fact that most microphones (except for the best
> small-diaphragm figure-8s and certain rather noisy omnis) don't have
> the same frequency response at all angles of incidence. So all our
> "virtual microphones" have rather complex, irregular response--that's
> another reason I tend to favor a super- or hypercardioid for "M".

I hadn't read ahead. You clearly understand the point I
made above.

>
> However, I'll also point out that the analog of using a non-flat S mike
> is processing the S channel independently of the M channel--and there is
> a long tradition of doing exactly that. One of the attractions of M/S
> (whether the recording is made originally that way, or whether another
> type of X/Y recording is matrixed to M/S) is that the M and S channels
> can be equalized independently or processed in other ways independently,
> then rematrixed to L/R stereo.

You want to make sure that any such manipulation that is
frequency dependant be done with linear phase filters and
that the channel not processed always be delayed by the
group delay of the filter to keep the two channels time
coherent. Changing the relative phase of M and S outputs
also has a large effect on source placement within the image.

All of this having to do with frequency dependant polar
responses and the consequence on imaging applies as well to
the XY configuration. At one extreme, look at the
frequencies where the polar plot gets close to round and all
those frequencies will be moved to the center of the image.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

locosoundman wrote:
> Great thread - thanks for all of the information everyone.
>
> In general I go with ORTF or some near-coincident variant therof but I
> like to use spaced-pair techniques on large ensembles when the room
> permits, or if I am using two stereo pairs in conjunction - one to
> accent something like a choir, in which case I use a coincident pair
> on the accent to get a strong center and clear localisation to better
> blend with the diffuse image of the spaced pair - usually a nice
> effect. I prefer to use coicindent methods simply for the effect of a
> narrower image with a strong center, to be able to control the width
> of the image later without phase problems, or for sound that will end
> up on video.

Sounds like a great idea to me. As I suggested in another
response, the best thing with stereo techniques is to try
things 'til you find configurations you like. The theory
doesn't go very far toward explaining what really happens.

> I have heard much about the supposed advantage of MS over XY because
> of the ability to control stereo width after the fact, but I have
> never used it due to the complications of rigging it.

There is really very little difference between XY and MS
except for the fact that the stuff usually of greater
interest is on the axis of the M in MS. OTOH, in the plots
I've looked at, the frequency response of a mic at +/- 45
degrees, the most common XY angle, is not very different
from on axis. You generally have to go further around
toward the back to begin to see signifigant variations.

In fact, XY can be converted to MS after the fact for the
same manipulations. Just use the DAW function that
transforms from LR to MS. The result can be remixed when
going back to LR to widen or narrow the image.

I've not played at all with MS manipulations other than
remixing at different ratios going to LR but as I responded
to David, if you are doing any frequency response
manipulation of just the M or just the S, use a linear phase
filter (equalizer) and be sure to delay the other side by
the same amount as the group delay of the linear phase filter.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

locosoundman wrote:
> Great thread - thanks for all of the information everyone.
>
> In general I go with ORTF or some near-coincident variant therof but I
> like to use spaced-pair techniques on large ensembles when the room
> permits, or if I am using two stereo pairs in conjunction - one to
> accent something like a choir, in which case I use a coincident pair
> on the accent to get a strong center and clear localisation to better
> blend with the diffuse image of the spaced pair - usually a nice
> effect. I prefer to use coicindent methods simply for the effect of a
> narrower image with a strong center, to be able to control the width
> of the image later without phase problems, or for sound that will end
> up on video.

Sounds like a great idea to me. As I suggested in another
response, the best thing with stereo techniques is to try
things 'til you find configurations you like. The theory
doesn't go very far toward explaining what really happens.

> I have heard much about the supposed advantage of MS over XY because
> of the ability to control stereo width after the fact, but I have
> never used it due to the complications of rigging it.

There is really very little difference between XY and MS
except for the fact that the stuff usually of greater
interest is on the axis of the M in MS. OTOH, in the plots
I've looked at, the frequency response of a mic at +/- 45
degrees, the most common XY angle, is not very different
from on axis. You generally have to go further around
toward the back to begin to see signifigant variations.

In fact, XY can be converted to MS after the fact for the
same manipulations. Just use the DAW function that
transforms from LR to MS. The result can be remixed when
going back to LR to widen or narrow the image.

I've not played at all with MS manipulations other than
remixing at different ratios going to LR but as I responded
to David, if you are doing any frequency response
manipulation of just the M or just the S, use a linear phase
filter (equalizer) and be sure to delay the other side by
the same amount as the group delay of the linear phase filter.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Edwin Hurwitz]

In article >,
Bob Cain > wrote:

> But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
> in the audience has made it useless unless you are really
> close to center and even then it just doesn't come out right.
>
>
> Bob

I don't think that the poster was referring to stereo sound
reinforcement, but recording an event that had sound reinforcement as a
variable, as opposed to a straight acoustic event.


Edwin

[Edwin Hurwitz]

In article >,
Bob Cain > wrote:

> But why would one be doing stereo with sound reinforcement?
> The few times I've tried it the variation due to position
> in the audience has made it useless unless you are really
> close to center and even then it just doesn't come out right.
>
>
> Bob

I don't think that the poster was referring to stereo sound
reinforcement, but recording an event that had sound reinforcement as a
variable, as opposed to a straight acoustic event.


Edwin

[Ed Anson]

David Satz wrote:

> It's significant that these are not only small-diapragm designs but also
> _single-diaphragm_ designs. And let's not forget the Neumann KM 120:
>
> http://www.neumann.com/infopool/mics/produkte.php?ProdID=km100
>
> Oddly I've never heard from anyone who has ever used it--and I've
> asked around repeatedly. Here goes again: If anyone here has used
> this microphone, could you please comment on its sound? I sometimes
> use spaced (!) figure-8s for stereo vocal recording, and can imagine
> that a response characteristic as shown in Neumann's diagrams might
> be useful for that application, or at least worth trying.

Since you asked: I use a Neumann KM120 with a KM140. It sounds good to
me. But then I haven't had occasion to critically compare it with
anything else in its class.

[Ed Anson]

David Satz wrote:

> It's significant that these are not only small-diapragm designs but also
> _single-diaphragm_ designs. And let's not forget the Neumann KM 120:
>
> http://www.neumann.com/infopool/mics/produkte.php?ProdID=km100
>
> Oddly I've never heard from anyone who has ever used it--and I've
> asked around repeatedly. Here goes again: If anyone here has used
> this microphone, could you please comment on its sound? I sometimes
> use spaced (!) figure-8s for stereo vocal recording, and can imagine
> that a response characteristic as shown in Neumann's diagrams might
> be useful for that application, or at least worth trying.

Since you asked: I use a Neumann KM120 with a KM140. It sounds good to
me. But then I haven't had occasion to critically compare it with
anything else in its class.

[Bob Cain]

Edwin Hurwitz wrote:

>
> I don't think that the poster was referring to stereo sound
> reinforcement, but recording an event that had sound reinforcement as a
> variable, as opposed to a straight acoustic event.

Thank you, Edwin. Confusion resolved. I was baffled by the
responses to my question and now I know why. :-)

I've been to a few large-hall surround supported shows put
on by some local Creative Labs folks who are into that and
avante garde arts and I've tried to get binaural recordings
of them. I was utterly frustrated by the extent to which
_everything_ changes with the slightest head motion.

It's not nearly so bad if the reinforcement is mono but
still, the slightest motion from left to right can
dramatically pull the apparent source to one side or the
other. I've about given up trying to get anything live in
stereo that isn't up close and cozy.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Edwin Hurwitz wrote:

>
> I don't think that the poster was referring to stereo sound
> reinforcement, but recording an event that had sound reinforcement as a
> variable, as opposed to a straight acoustic event.

Thank you, Edwin. Confusion resolved. I was baffled by the
responses to my question and now I know why. :-)

I've been to a few large-hall surround supported shows put
on by some local Creative Labs folks who are into that and
avante garde arts and I've tried to get binaural recordings
of them. I was utterly frustrated by the extent to which
_everything_ changes with the slightest head motion.

It's not nearly so bad if the reinforcement is mono but
still, the slightest motion from left to right can
dramatically pull the apparent source to one side or the
other. I've about given up trying to get anything live in
stereo that isn't up close and cozy.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[David Satz]

Sugarite wrote:

> This is leading towards a debate over whether two matched cardioids
> are in fact a truer match than either side of a fig-8. I'm of the
> opinion that the matched card's are a truer match, mostly because you
> can't as easily test the internal bipolar matching on a mic-by-mic
> basis like matching two card's.

May I take a closer look at this rather mysterious course of logic? If
I didn't know better, I'd think you were saying that the ease of testing
which you imagine in a thought experiment (!) should take precedence over
the accuracy of competent real-world measurements.

But even granting that, I think your logical conclusion would be: "If I
had to document the front/back symmetry myself, I'd prefer two cardioids.
Then I'd have my own way to make the measurements, so I would feel more
comfortable trusting the results." Human to human, I could respect that.

Still, that isn't quite the same as the broad claim that "cardioids match
better than the front and back of a figure 8" (which is what you said).
The two statements are about different things--the first one is about
your own mindset, while the other one is about microphone capsules, no?


> It's impossible to test both sides of a fig-8 with that level of
> precision. All you can do is "read curves".

If I didn't know better, I'd think you were claiming to know the level
of precision of curves which you've never seen and don't know a thing
about. Also, in this case I can do a bit more than "read curves," since
the ones I described were those of a pair of capsules which I used for
nearly 25 years; I made several hundred live recordings with them. And
I've had even longer experience with frequency response curves from that
particular measurement chamber.

In 1974 I even did some blind testing--I was sent a pair of test capsules
with no indication of their characteristics. I tried them on a recording
and reported back that I had heard a response elevation of 2 dB between
a certain pair of upper midrange frequencies. I was then allowed to see
the response plots; I had estimated them exactly. I don't claim that I
could do that every time, of course. But I feel I do have a real luxury,
which is that I can indeed "read" these curves and, in relation to them,
I also know from long experience what the results sound like.

Given that situation I don't share the dismissive attitude that some
people have toward response plots--I find that they can often tell me
quite a bit about a microphone.

As you may know, ten of the manufacturers in the AES Working Group on
microphone specifications have recently completed a "round robin" test
in which each of them submitted one cardioid microphone which they and
all the other manufacturers measured, so that they could compare notes
on how they measure microphone response and how they present the results.
A paper was presented at the recent Tonmeistertagung in Germany which
described some of the results of this "round robin" test (I was the
translator for that) and I hear that there was also some discussion or
perhaps a paper about this at the most recent AES convention as well.

--best regards

[David Satz]

Sugarite wrote:

> This is leading towards a debate over whether two matched cardioids
> are in fact a truer match than either side of a fig-8. I'm of the
> opinion that the matched card's are a truer match, mostly because you
> can't as easily test the internal bipolar matching on a mic-by-mic
> basis like matching two card's.

May I take a closer look at this rather mysterious course of logic? If
I didn't know better, I'd think you were saying that the ease of testing
which you imagine in a thought experiment (!) should take precedence over
the accuracy of competent real-world measurements.

But even granting that, I think your logical conclusion would be: "If I
had to document the front/back symmetry myself, I'd prefer two cardioids.
Then I'd have my own way to make the measurements, so I would feel more
comfortable trusting the results." Human to human, I could respect that.

Still, that isn't quite the same as the broad claim that "cardioids match
better than the front and back of a figure 8" (which is what you said).
The two statements are about different things--the first one is about
your own mindset, while the other one is about microphone capsules, no?


> It's impossible to test both sides of a fig-8 with that level of
> precision. All you can do is "read curves".

If I didn't know better, I'd think you were claiming to know the level
of precision of curves which you've never seen and don't know a thing
about. Also, in this case I can do a bit more than "read curves," since
the ones I described were those of a pair of capsules which I used for
nearly 25 years; I made several hundred live recordings with them. And
I've had even longer experience with frequency response curves from that
particular measurement chamber.

In 1974 I even did some blind testing--I was sent a pair of test capsules
with no indication of their characteristics. I tried them on a recording
and reported back that I had heard a response elevation of 2 dB between
a certain pair of upper midrange frequencies. I was then allowed to see
the response plots; I had estimated them exactly. I don't claim that I
could do that every time, of course. But I feel I do have a real luxury,
which is that I can indeed "read" these curves and, in relation to them,
I also know from long experience what the results sound like.

Given that situation I don't share the dismissive attitude that some
people have toward response plots--I find that they can often tell me
quite a bit about a microphone.

As you may know, ten of the manufacturers in the AES Working Group on
microphone specifications have recently completed a "round robin" test
in which each of them submitted one cardioid microphone which they and
all the other manufacturers measured, so that they could compare notes
on how they measure microphone response and how they present the results.
A paper was presented at the recent Tonmeistertagung in Germany which
described some of the results of this "round robin" test (I was the
translator for that) and I hear that there was also some discussion or
perhaps a paper about this at the most recent AES convention as well.

--best regards

[Sugarite]

> > This is leading towards a debate over whether two matched cardioids
> > are in fact a truer match than either side of a fig-8. I'm of the
> > opinion that the matched card's are a truer match, mostly because you
> > can't as easily test the internal bipolar matching on a mic-by-mic
> > basis like matching two card's.
>
> May I take a closer look at this rather mysterious course of logic? If
> I didn't know better, I'd think you were saying that the ease of testing
> which you imagine in a thought experiment (!) should take precedence over
> the accuracy of competent real-world measurements.

[snip]

Reversing cardioid signals is hardly experimentation. Two card's can be
trusted as a 100% match when they produce no perceivable signal when one is
inverted against the other. That catches aspects that aren't even
understood, much less measureable. That is a far more reliable test than
any that can be applied to a fig-8, except if you had a matched pair of fig
8's that stay matched if you turn one around, something I've never heard of
happening. If you reverse one or both of the fig-8's in Blumlein format
you'll get different imaging every time. The dependence on a balanced fig-8
in MS format is equally severe.

[hank alrich]

Sugarite wrote:

> Reversing cardioid signals is hardly experimentation. Two card's can be
> trusted as a 100% match when they produce no perceivable signal when one is
> inverted against the other. That catches aspects that aren't even
> understood, much less measureable. That is a far more reliable test than
> any that can be applied to a fig-8, except if you had a matched pair of fig
> 8's that stay matched if you turn one around, something I've never heard of
> happening. If you reverse one or both of the fig-8's in Blumlein format
> you'll get different imaging every time. The dependence on a balanced fig-8
> in MS format is equally severe.

Since there is no way in the presently known universe to put two objects
in the same place at the same time, how can wavefronts that arrive at
different times null? Is this a fantasy test?

--
ha

[Bob Cain]

hank alrich wrote:

> Since there is no way in the presently known universe to put two objects
> in the same place at the same time, how can wavefronts that arrive at
> different times null? Is this a fantasy test?

Not at all, Hank. While they can't be at the same place,
they can be at the same distance by placing one atop the
other pointing in opposite directions with their diaphragms
in the same plane and with that plane passing through the
source.

Here's a pic of a MS employing three little Panasonic WM55A
cards that I made to experiment with:

http://www.arcanemethods.com/MS-Ball-Off.gif

Yes, things arriving from off the horizontal plane will have
some TOA difference so there is assymetry that way but for
the direct sound, it can be quite time coherent.

That there is a front to back distance between M and S on
axis is ameliorated by the M being in the null of the S
there. At 90 degrees the distance between M and S is the same.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Ty Ford]

On Sat, 27 Nov 2004 03:19:54 -0500, Bob Cain wrote
(in article >):

>
>
> hank alrich wrote:
>
>> Since there is no way in the presently known universe to put two objects
>> in the same place at the same time, how can wavefronts that arrive at
>> different times null? Is this a fantasy test?
>
> Not at all, Hank. While they can't be at the same place,
> they can be at the same distance by placing one atop the
> other pointing in opposite directions with their diaphragms
> in the same plane and with that plane passing through the
> source.
>
> Here's a pic of a MS employing three little Panasonic WM55A
> cards that I made to experiment with:
>
> http://www.arcanemethods.com/MS-Ball-Off.gif
>
> Yes, things arriving from off the horizontal plane will have
> some TOA difference so there is assymetry that way but for
> the direct sound, it can be quite time coherent.
>
> That there is a front to back distance between M and S on
> axis is ameliorated by the M being in the null of the S
> there. At 90 degrees the distance between M and S is the same.
>
>
> Bob

Then there's the consideration of how the mic bodies might alter the results
because of their obstructional presence.

Regards,

Ty Ford



-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com

[ScotFraser]

<< While they can't be at the same place,
they can be at the same distance by placing one atop the
other pointing in opposite directions with their diaphragms
in the same plane and with that plane passing through the
source. >><BR><BR>

Which is great for sound arriving from a single direction, i.e. an anechoic
situation. In any desirable recording venue, obviously the distance thing again
becomes slightly approximate. In the end, everything we do is slightly
approximate anyway, so what's a few millimeters this way or that?

Scott Fraser

[Mike Rivers]

In article > writes:

> > Reversing cardioid signals is hardly experimentation. Two card's can be
> > trusted as a 100% match when they produce no perceivable signal when one is
> > inverted against the other.

> Since there is no way in the presently known universe to put two objects
> in the same place at the same time, how can wavefronts that arrive at
> different times null? Is this a fantasy test?

Everything in recorded audio is fantasy. Which fantasy do you like?
It's all a matter of how "close enough" do you want to get. Even if
you could put both microphones in the same place, you couldn't build
two capsules closely enough to identical so that they'd cancel
completely at all frequencies, from all angles. It's just a way to
check whether you're in the ballpark.

Grossly mismatched mics will give strange results when used as a
stereo pair. Mics that are pretty close will work quite well.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo

[hank alrich]

ScotFraser wrote:

> In the end, everything we do is slightly
> approximate anyway, so what's a few millimeters this way or that?

Possibly quite a lot if looking for complete null with two opposite
polarity, separately housed cardioids?

--
ha

[Ron Capik]

Mike Rivers wrote:

> < ...snip.. >
>
> Everything in recorded audio is fantasy. Which fantasy do you like?
> It's all a matter of how "close enough" do you want to get. Even if
> you could put both microphones in the same place, you couldn't build
> two capsules closely enough to identical so that they'd cancel
> completely at all frequencies, from all angles. It's just a way to
> check whether you're in the ballpark.
>
> Grossly mismatched mics will give strange results when used as a
> stereo pair. Mics that are pretty close will work quite well.
>
> --
> I'm really Mike Rivers )

In example, I did an MS experiment with a bluegrass group
a few weeks ago. They play single mic style so recordings
would be in mono. To add some space to the (live) recording
(without detracting from their single mic look) I set up two
ATM-35 as the S output. [I did do some EQ to help match
the S and M response. Note: their single mic is an AT 4033
stuck in an old classic RCA shell, so I don't have a clue what it's
response is. (Then too, I wrote a vector analysis program that
display phase coherence info. to help with the EQ...) ]

Anyway, the added space greatly enhanced the recording.
In contrast, a friend's group just did a (single mic) studio
recording with reverb to add space ...and to me it just sounds
wrong.

In the art of recording YMMV is a key phrase. ;-)

Later...

Ron Capik
--

[Bob Cain]

Ty Ford wrote:

> Then there's the consideration of how the mic bodies might alter the results
> because of their obstructional presence.

For sure. Grills and bodys have very large effects above 10
kHz. That's why I made my DIY MS a front address with an
axially symmetric body behind it. It's way too blunt but
that's what I had on hand. I've spent very little time at
this point evaluating that particular iteration. I know the
stereo image is good but haven't characterized the response.

If I were to ever build a commercial version of the the 3
capsule M/S I'd be paying special experimental attention to
that factor. I'd like to do one with the array at the end
of a body shaped like an Earthworks TC30K for example. One
of these days.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

ScotFraser wrote:
> << While they can't be at the same place,
> they can be at the same distance by placing one atop the
> other pointing in opposite directions with their diaphragms
> in the same plane and with that plane passing through the
> source. >><BR><BR>
>
> Which is great for sound arriving from a single direction, i.e. an anechoic
> situation. In any desirable recording venue, obviously the distance thing again
> becomes slightly approximate.

Correct, but my thinking is that for the usual focus of
attention, the direct sound from what's arrayed in front and
to the sides, it will be pretty optimally captured from an
M/S relative delay standpoint and the diffuse or reverberant
sound arriving with a signifigant azimuth angle will be what
is time skewed. Since that part is naturally skewed with
strong frequency dependancy and without any kind of precise
image requirements, inaccuracy there shouldn't matter too
much. I may be wrong but I don't think the time coherence
of ambience is very important.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[KyleSong]

>> Everything in recorded audio is fantasy. Which fantasy do you like?
>> It's all a matter of how "close enough" do you want to get. Even if
>> you could put both microphones in the same place, you couldn't build
>> two capsules closely enough to identical so that they'd cancel
>> completely at all frequencies, from all angles.

I've liked the sound I get from a U87 in Omni, and a Royer R121 as the
bi-directional mic. I doubt the two responses are similar enough for
mathematically 'perfect' MS, but the results sound 'good' to me.

[Bob Cain]

KyleSong wrote:
>>>Everything in recorded audio is fantasy. Which fantasy do you like?
>>>It's all a matter of how "close enough" do you want to get. Even if
>>>you could put both microphones in the same place, you couldn't build
>>>two capsules closely enough to identical so that they'd cancel
>>>completely at all frequencies, from all angles.
>
>
> I've liked the sound I get from a U87 in Omni, and a Royer R121 as the
> bi-directional mic. I doubt the two responses are similar enough for
> mathematically 'perfect' MS, but the results sound 'good' to me.

Where you need to look for 'goodness' with respect to
matching is in the spatial distribution of instrument
images. If the M and S aren't matched in their response
curves then the reproduced image of an instrument that is
off axis can get quite blurred with some part of its
spectrum in one place and other parts in another place. M/S
is intensity based so if relative intensity is varying with
frequency so are the image locations. A few dB difference
in response at a frequency is like a few dB pan difference
at that frequency.

Percussion, being especially broad band, is particularly
sensitive to this mismatch effect.

If, OTOH, you are multi-tracking with MS and your source is
always on axis and compact so that you are relying on the S
for ambience only you won't be as sensitive to mismatch and
the MS panning plugins like Waves' "Stereo Imager" will
preserve the spatial coherence while rotating the image.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[KyleSong]

Bob Cain wrote:

> If, OTOH, you are multi-tracking with MS and your source is
> always on axis and compact so that you are relying on the S
> for ambience only you won't be as sensitive to mismatch and
> the MS panning plugins like Waves' "Stereo Imager" will
> preserve the spatial coherence while rotating the image.

Thanks for the point - I get it, and hadn't considered that before.

generally I do use MS in situations where most of the direct signal is in
front of the array, with most of the sides being ambience. In that case, I
like the color of the sound I get with the U87 and Royer R121. I'm guessing
that the 87 has more top, so perhaps high end will be biased to the middle
in this setup.

I hadn't encountered the situation of instruments to the side that you're
talking about, so if (when) that situation does arise, I'll listen hard for
discrepancies such as the ones you describe.

Thanks for the education.

Kyle

[ScotFraser]

<< I may be wrong but I don't think the time coherence
of ambience is very important. >><BR><BR>

Right. I think we have a lot of leeway with ambience. I often delay ambience
tracks a bit to make them more incoherent, thus less colorizing to the direct
tracks.

Scott Fraser

[ScotFraser]

<< Possibly quite a lot if looking for complete null with two opposite
polarity, separately housed cardioids? >><BR><BR>

That not nulled would be in the canine stratus frequency-wise, which is an area
where I think we have room for a lot of slop, vis a vis perceived accuracy.

Scott Fraser

[Sugarite]

"David Satz" > wrote in message
om...
> Sugarite wrote:
>
> > This is leading towards a debate over whether two matched cardioids
> > are in fact a truer match than either side of a fig-8. I'm of the
> > opinion that the matched card's are a truer match, mostly because you
> > can't as easily test the internal bipolar matching on a mic-by-mic
> > basis like matching two card's.
>
> May I take a closer look at this rather mysterious course of logic? If
> I didn't know better, I'd think you were saying that the ease of testing
> which you imagine in a thought experiment (!) should take precedence over
> the accuracy of competent real-world measurements.
>
> But even granting that, I think your logical conclusion would be: "If I
> had to document the front/back symmetry myself, I'd prefer two cardioids.
> Then I'd have my own way to make the measurements, so I would feel more
> comfortable trusting the results." Human to human, I could respect that.
>
> Still, that isn't quite the same as the broad claim that "cardioids match
> better than the front and back of a figure 8" (which is what you said).
> The two statements are about different things--the first one is about
> your own mindset, while the other one is about microphone capsules, no?

**** mindset. This isn't a philosophical issue. Take two cardioids, place
them side-by-side in front of any suitably complex sound source. If you
oppose the signals from the two mics and all you get is the mics'
self-noise, then they're matched with as much certainty as this industry
affords. Everything including any aberrations from the two mics being close
to each other would show up if they weren't matched close enough to be
called "perfect" for any reasonable application.

Show me a test that proves any fig-8 can be trusted to that level of
precision and I'll certainly consider it. The importance of matched mics
for what I do is pretty much paramount. Curves don't cut it.

[Sugarite]

> >> Everything in recorded audio is fantasy. Which fantasy do you like?
> >> It's all a matter of how "close enough" do you want to get. Even if
> >> you could put both microphones in the same place, you couldn't build
> >> two capsules closely enough to identical so that they'd cancel
> >> completely at all frequencies, from all angles.
>
> I've liked the sound I get from a U87 in Omni, and a Royer R121 as the
> bi-directional mic. I doubt the two responses are similar enough for
> mathematically 'perfect' MS, but the results sound 'good' to me.

Part of me wants to burn you at the stake for such a wanton mismatch, but at
the same time I applaud your achievement of self-satisfaction despite the
technical disparity.

It'd be nice to have two groups, rec.audio.pro.theory and
rec.audio.pro.practice, because there is so much daylight between the two
it's ****ing nauseating.

[hank alrich]

Sugarite wrote:

> Take two cardioids, place
> them side-by-side in front of any suitably complex sound source.

I've done that, with several different pairs of like mics, and I did not
get a truly decent null. All one must do is listen to how it sounds with
both mics in same polarity and then with one mic and notice there is a
difference, even with decently matched levels.

--
ha

[KyleSong]

> Part of me wants to burn you at the stake for such a wanton mismatch, but at
> the same time I applaud your achievement of self-satisfaction despite the
> technical disparity.


Oooh burned Wantons - not a good grade in cooking school, but they taste SO
good :)

Seriously, thanks for the post.

I really DO have good ears, and I really DO like the sound. I generally use
it for drum ambience, so the color is a matter of taste. If I was doing this
with a string quartet, especially one that was spread out around the
microphone, then I'm sure I would choose differently.

The color of the room ambience on the drums is really great with this
combination, and like I said before, there isn't any source that's placed
outside of the front of the array, so the stereo placement isn't being
compromised.

[WillStG]

<< (ScotFraser) >>
<< In the end, everything we do is slightly
approximate anyway, so what's a few millimeters this way or that? >>

The difference between how a KM184 and a KM140 sound, as according to
Neumann the capsule being placed a few millimeters different is the only
difference techincally between the two mics, one of which you have said you
much prefer over the other.... <g> Or maybe the difference between how some
dual capsule mics and some single capsule mic sound in omni, as the dual
capsule introduces just the teensiest bit of distance.

But anyway, if MS wasn't working for me I might think it was for reasons
other than a slight difference between the response on the front and back of my
chosen figure 8 mic.

Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

<< (ScotFraser) >>
<< I often delay ambience
tracks a bit to make them more incoherent, thus less colorizing to the direct
tracks. >>

Do you roll off the low end a lot on your ambient tracks Scott?



Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

<< "Sugarite" >>
<< Part of me wants to burn you at the stake for such a wanton mismatch, but at
the same time I applaud your achievement of self-satisfaction despite the
technical disparity.

It'd be nice to have two groups, rec.audio.pro.theory and
rec.audio.pro.practice, because there is so much daylight between the two
it's ****ing nauseating. >>

I get the impression your left brain is a lot more muscular than your
right brain is. The right brain relates better to what *is* though, and
sometimes the left brain being busy telling you what *should be* when you are
working will get in your way, impede your dealing with what is actually in
front of you.

Besides, do you have left and right EARS that are perfectly matched? I
hear 80hz much better on my left side than on my right, and have a dip at 2k of
a 1/2 db or so on that side as well, last time I had them tested.

Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[ScotFraser]

<< The difference between how a KM184 and a KM140 sound, as according to
Neumann the capsule being placed a few millimeters different is the only
difference techincally between the two mics, one of which you have said you
much prefer over the other.... <g> >><BR><BR>

Actually I've never used a KM184 in a critical situation, so I don't have an
opinion about them. You must be thinking of some other guy named Scott.

Scott Fraser

[Scott Dorsey]

ScotFraser > wrote:
><< The difference between how a KM184 and a KM140 sound, as according to
>Neumann the capsule being placed a few millimeters different is the only
>difference techincally between the two mics, one of which you have said you
>much prefer over the other.... <g> >><BR><BR>
>
>Actually I've never used a KM184 in a critical situation, so I don't have an
>opinion about them. You must be thinking of some other guy named Scott.

It was probably me. I like the KM140 better.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[WillStG]

(ScotFraser)

>Actually I've never used a KM184 in a critical situation, so I don't have
>anopinion about them. You must be thinking of some other guy named Scott.

Actually you did say so once Scott, at least by deductive reasoning. You
said in a U87 thread that comparing a KM184 to a Scheops CM62 was unfair due to
the cost differential, that a comparison to a KM140 was a closer comparison,
and that you "slightly prefer the depiction of the upper bass range of the
KM140."

Not to bust your chops or anything... <g>


Will Miho
NY Music & TV Audio Guy
Audioist / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[TonyP]

"Sugarite" > wrote in message
...
> **** mindset. This isn't a philosophical issue. Take two cardioids,
place
> them side-by-side in front of any suitably complex sound source. If you
> oppose the signals from the two mics and all you get is the mics'
> self-noise, then they're matched with as much certainty as this industry
> affords. Everything including any aberrations from the two mics being
close
> to each other would show up if they weren't matched close enough to be
> called "perfect" for any reasonable application.
>
> Show me a test that proves any fig-8 can be trusted to that level of
> precision and I'll certainly consider it. The importance of matched mics
> for what I do is pretty much paramount. Curves don't cut it.

I have to wonder how you could get the two mics to occupy the EXACT same
space at the same time to perform such a test?
Side by side don't cut it either.

TonyP.

[Arny Krueger]

"TonyP" > wrote in message
u

> I have to wonder how you could get the two mics to occupy the EXACT
> same space at the same time to perform such a test?
> Side by side don't cut it either.

As close as you'll get practially might be obtained by using miniature
mics. I followed up on some recent posts about Knowles mics that Digi Key
has in their catalog and found that they are actually 0.1" OD. Those were
omnis, but I think they also have some really small directional mics in
their catalog.

My point being that 1" mics quite obviously can't be coincident at paractial
audio frequencies, and IME neither can 1/2" mics. However, practially nearly
coincident up to say 10 KHz could solve a lot of problems.

The wavelength of 10 KHz is something like 1.3 inches, so mics that are 0.1"
center to center are still about 30 degrees apart in terms of phase. The
good news is that 30 degrees is a long ways from 180 degrees. The cosine of
this angle is almost 0.9, so cancellation on the order of 20 dB at 10 KHz
seems possible.

[Carey Carlan]

"Arny Krueger" > wrote in
:

> The wavelength of 10 KHz is something like 1.3 inches, so mics that
> are 0.1" center to center are still about 30 degrees apart in terms of
> phase. The good news is that 30 degrees is a long ways from 180
> degrees. The cosine of this angle is almost 0.9, so cancellation on
> the order of 20 dB at 10 KHz seems possible.

Also, we're not interested in the stereo effect of vertical spacing. Most
sources are spread in the horizontal plane, so having mics coincident
vertically is usually enough.

A pair of side address mics, one atop the other can get very close
vertically and almost precisely aligned horizontally (to the limitation of
the width of the capsule).

[hank alrich]

Arny Krueger wrote:

> As close as you'll get practially might be obtained by using miniature
> mics.

Whereas in practicality we might want to use some other type of mic. I
guess I'm just sceptical about the usefulness of trying to null
separate, real world and of various size, cardioid mic pairs. IME it
hasn't worked well. Maybe that's just another reason folks bother to
build anechoic chambers.

--
ha

[ScotFraser]

<< Do you roll off the low end a lot on your ambient tracks Scott?
>><BR><BR>

I don't really have a blanket policy on that, it's really on a case by case
basis, but probably a low rolloff is unconsciously in place due to mic choice,
since I'm more interested in mid & higher response in the ambient tracks.
Scott Fraser

[Ron Capik]

hank alrich wrote:

> Arny Krueger wrote:
>
> > As close as you'll get practially might be obtained by using miniature
> > mics.
>
> Whereas in practicality we might want to use some other type of mic. I
> guess I'm just sceptical about the usefulness of trying to null
> separate, real world and of various size, cardioid mic pairs. IME it
> hasn't worked well. Maybe that's just another reason folks bother to
> build anechoic chambers.
> --
> ha

All this "phonons dancing on the head of a pin" stuff has me wondering
what has become of the usual mantra of this group: use your ears... ?

If one needs to account for and correct every little phase anomaly in
the system before they record they'd never get any recording done.

In my experience theory helps but the real proof is in the experimental
(or in this case recording) results.

[OK, I'll admit some of these techno-flame-wars are fun to follow. ]

Later...

Ron Capik <<< cynic in training >>>
--

[hank alrich]

Ron Capik wrote:

> All this "phonons dancing on the head of a pin" stuff has me wondering
> what has become of the usual mantra of this group: use your ears... ?

I guess a paraphrasation of what's talking here is trying to get at
audible image anomalies when using an M/S config. The tangent developed
around the question of useful null from separate cardioids. My points
remain that I have no interest in laboratory results using the tiniest
available cardioids because the liklihood of me wanting to use those in
recording work is low, and that I have little faith in the achievement
of null with the real world mics, having been there and done that.

> If one needs to account for and correct every little phase anomaly in
> the system before they record they'd never get any recording done.

Right, but in the context of stable imaging across the spectrum, little
phase anomalies can make larger than expected differences.

> In my experience theory helps but the real proof is in the experimental
> (or in this case recording) results.

Amen.

> [OK, I'll admit some of these techno-flame-wars are fun to follow. ]

You're a sick man, Ron, but you knew that already.

> Later...
>
> Ron Capik <<< cynic in training >>>

The Cynical Olympics, new on FOX!

--
ha

[hank alrich]

Ron Capik wrote:

> All this "phonons dancing on the head of a pin" stuff has me wondering
> what has become of the usual mantra of this group: use your ears... ?

I guess a paraphrasation of what's talking here is trying to get at
audible image anomalies when using an M/S config. The tangent developed
around the question of useful null from separate cardioids. My points
remain that I have no interest in laboratory results using the tiniest
available cardioids because the liklihood of me wanting to use those in
recording work is low, and that I have little faith in the achievement
of null with the real world mics, having been there and done that.

> If one needs to account for and correct every little phase anomaly in
> the system before they record they'd never get any recording done.

Right, but in the context of stable imaging across the spectrum, little
phase anomalies can make larger than expected differences.

> In my experience theory helps but the real proof is in the experimental
> (or in this case recording) results.

Amen.

> [OK, I'll admit some of these techno-flame-wars are fun to follow. ]

You're a sick man, Ron, but you knew that already.

> Later...
>
> Ron Capik <<< cynic in training >>>

The Cynical Olympics, new on FOX!

--
ha

[KyleSong]

Ron Capik wrote:

> In my experience theory helps but the real proof is in the experimental
> (or in this case recording) results.

I agree. Knowing and understanding audio theory will help you make informed
decisions, and give you a good set of options to choose from. Ditto
experience. But each of these is only a starting point. There is not "Art by
Number" method that will produce great results every time.

This is not an argument for ignorance. You must have both: a good
understanding of what is happening and is possible, AND an open mind and
open set of ears to hear how its sounding THIS time.

In my opinion, the hardest thing about any art is to keep your
experience/technique handy, but not in the driver's seat. This means
avoiding the bias that knowledge brings, while still using it to your
advantage.

For instance, if you spend $4,000 on a beautiful tube compressor, and you
come to a track that is the sort of thing that you bought that piece FOR, it
is a VERY difficult thing to admit to yourself (and hear) that in this case,
the device is not working as well as something else.

Another example is avoiding the theoretical 'misuse' of unmatched
microphones in an M/S array that just happens to sound 'good'.

The dilemma is in having good knowledge / experience to draw from, and
listening like its the first time, all at once. This is the basic struggle
of any artist in any medium. To have the chops to do it well, and at the
same time, to let your subconscious voice lead the way.

The purpose of art is to create an emotional (and / or intellectual)
response in the audience. Technique helps in creation, but it is the result
that matters.

You will do better work on a more consistent basis with knowledge. But your
work will be best if it speaks to humanity, and that is something that
cannot be quantified in technique alone.

Since I don't believe that there has EVER been a recording that sounded like
musicians playing live in a room, I think that all recordings are on some
level impressionistic. Even if the result is intended to mimic a natural
experience, it may well be through the judicious application of several
processes that the most "natural" feeling recording results.

Based on this belief, I don't think you can argue science past a certain
point in audio. You can argue HOW something works, but it is how it sounds
that matters in the end. Of course "how it works" informs "how it sounds",
so again, this is not an argument, or an excuse for ignorance. I'm not
saying "**** science, it only matters how it sounds" but I AM saying that
science alone cannot describe the entirety of what we are all trying to do
here, and that when theory becomes in opposition to results that are ideal
for a certain musical application, that the science must step aside to
accommodate the human artistic experience.

[KyleSong]

Ron Capik wrote:

> In my experience theory helps but the real proof is in the experimental
> (or in this case recording) results.

I agree. Knowing and understanding audio theory will help you make informed
decisions, and give you a good set of options to choose from. Ditto
experience. But each of these is only a starting point. There is not "Art by
Number" method that will produce great results every time.

This is not an argument for ignorance. You must have both: a good
understanding of what is happening and is possible, AND an open mind and
open set of ears to hear how its sounding THIS time.

In my opinion, the hardest thing about any art is to keep your
experience/technique handy, but not in the driver's seat. This means
avoiding the bias that knowledge brings, while still using it to your
advantage.

For instance, if you spend $4,000 on a beautiful tube compressor, and you
come to a track that is the sort of thing that you bought that piece FOR, it
is a VERY difficult thing to admit to yourself (and hear) that in this case,
the device is not working as well as something else.

Another example is avoiding the theoretical 'misuse' of unmatched
microphones in an M/S array that just happens to sound 'good'.

The dilemma is in having good knowledge / experience to draw from, and
listening like its the first time, all at once. This is the basic struggle
of any artist in any medium. To have the chops to do it well, and at the
same time, to let your subconscious voice lead the way.

The purpose of art is to create an emotional (and / or intellectual)
response in the audience. Technique helps in creation, but it is the result
that matters.

You will do better work on a more consistent basis with knowledge. But your
work will be best if it speaks to humanity, and that is something that
cannot be quantified in technique alone.

Since I don't believe that there has EVER been a recording that sounded like
musicians playing live in a room, I think that all recordings are on some
level impressionistic. Even if the result is intended to mimic a natural
experience, it may well be through the judicious application of several
processes that the most "natural" feeling recording results.

Based on this belief, I don't think you can argue science past a certain
point in audio. You can argue HOW something works, but it is how it sounds
that matters in the end. Of course "how it works" informs "how it sounds",
so again, this is not an argument, or an excuse for ignorance. I'm not
saying "**** science, it only matters how it sounds" but I AM saying that
science alone cannot describe the entirety of what we are all trying to do
here, and that when theory becomes in opposition to results that are ideal
for a certain musical application, that the science must step aside to
accommodate the human artistic experience.