[Roy W. Rising[_2_]]

Nick Brown wrote:
[snip]

Lastly, a ribbon mic with a figure-8 pattern could be used as the side
mic in an MS pair, along with your Schoeps. It doesn't produce a
dramatic stereo effect, but it's interesting, it gives you a little of
the character of each of the two mics.

Cheers,
Nick

Ribbon (velocity) mics are 90 degrees out of phase with condensers and
dynamics (pressure). The combination Nick describes indeed would yield and
*interesting* sound.

--
~
~ Roy
"If you notice the sound, it's wrong!"

[Nick Brown]

Roy W. Rising wrote:
Nick Brown wrote:
[snip]

Lastly, a ribbon mic with a figure-8 pattern could be used as the side
mic in an MS pair, along with your Schoeps. It doesn't produce a
dramatic stereo effect, but it's interesting, it gives you a little of
the character of each of the two mics.

Cheers,
Nick

Ribbon (velocity) mics are 90 degrees out of phase with condensers and
dynamics (pressure). The combination Nick describes indeed would yield and
*interesting* sound.


Interesting point. So when the two are combined the result would be...
comb filtering?

I'm not clear what you mean by "condensers and dynamics (pressure)" -
taken literally it would seem to imply that all condenser mics are
pressure operated, even the hypercardioid Schoeps under discussion here,
even the single-diaphram figure-8 condensers (Schoeps MK8, Sennheiser
MKH30). That can't be right, can it?

If combining air pressure and velocity information is inherently flawed,
wouldn't that flaw be manifest in every cardioid mic ever? I thought
that was how the cardioid pattern was formed.

What am I missing here?

Cheers,
Nick

[Scott Dorsey]

Nick Brown wrote:
Interesting point. So when the two are combined the result would be...
comb filtering?

Well, that always happens when you put two mikes together unless they are
in precisely the same place in space.

I'm not clear what you mean by "condensers and dynamics (pressure)" -
taken literally it would seem to imply that all condenser mics are
pressure operated, even the hypercardioid Schoeps under discussion here,
even the single-diaphram figure-8 condensers (Schoeps MK8, Sennheiser
MKH30). That can't be right, can it?

An omnidirectional microphone is sensitive to air pressure. A figure-8
microphone is sensitive to air velocity. Cardioids, hypercardioids, and
supercardioids are sensitive to both in varying degrees.

If combining air pressure and velocity information is inherently flawed,
wouldn't that flaw be manifest in every cardioid mic ever? I thought
that was how the cardioid pattern was formed.

Cardioid microphones are inherently flawed and will always have frequency
response that changes with direction. In general, the closer you get to
the edges of the spectrum (omni and figure-8), the better the off-axis
response will be.

Consequently if you compare the Schoeps cardioid and hypercardioid capsules,
you'll find the hypercardioid is actually cleaner off-axis than the regular
cardioid.

There are various tricks you can play to regularize the off-axis response
and some of them work better than others. Most microphone vendors use
a few of them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Nick Brown]

On 21 Jul 2008 14:07:52 -0400, (Scott Dorsey) wrote:

Nick Brown wrote:

[snip]

If combining air pressure and velocity information is inherently flawed,
wouldn't that flaw be manifest in every cardioid mic ever? I thought
that was how the cardioid pattern was formed.

Cardioid microphones are inherently flawed and will always have frequency
response that changes with direction. In general, the closer you get to
the edges of the spectrum (omni and figure-8), the better the off-axis
response will be.

Consequently if you compare the Schoeps cardioid and hypercardioid capsules,
you'll find the hypercardioid is actually cleaner off-axis than the regular
cardioid.

Thanks for the clarification.

So at least in terms of the effects of combining varying degrees of
pressure and velocity response, using a Schoeps 41 as a middle mic
alongside a figure-8 ribbon side mic doesn't seem to me significantly
more outlandish than say using a Beyer hypercardioid mid.

Cheers,
Nick

[Scott Dorsey]

Nick Brown wrote:

So at least in terms of the effects of combining varying degrees of
pressure and velocity response, using a Schoeps 41 as a middle mic
alongside a figure-8 ribbon side mic doesn't seem to me significantly
more outlandish than say using a Beyer hypercardioid mid.

You're talking about two totally different things.

Yes, you can combine a figure-8 and an omni together in order to get a
variety of different patterns. A lot of mikes do this, starting with the
original Altec 639. It doesn't work perfectly because the frequency response
of the two elements is never quite the same, so the response always changes
at least a little bit with the pattern control. Doing this, both microphones
are pointed straight ahead.

M-S miking is a totally different thing. It's a stereo microphone technique
using a figure-8 pointed toward the side and an omni pointed straight ahead
(which would be anywhere if it were a perfect omni, but because real world
omnis aren't pefectly omni, it's 90' from the axis of the cardioid) and a
matrix to generate right and left channels. It's actually an attempt to
get the same pattern as a coincident cardioid pair, but with microphones
that are cleaner off-axis.
--scott

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

[Nick Brown]

On 21 Jul 2008 15:22:25 -0400, (Scott Dorsey) wrote:

Nick Brown wrote:

So at least in terms of the effects of combining varying degrees of
pressure and velocity response, using a Schoeps 41 as a middle mic
alongside a figure-8 ribbon side mic doesn't seem to me significantly
more outlandish than say using a Beyer hypercardioid mid.

You're talking about two totally different things.

Yes, you can combine a figure-8 and an omni together in order to get a
variety of different patterns. A lot of mikes do this, starting with the
original Altec 639. It doesn't work perfectly because the frequency response
of the two elements is never quite the same, so the response always changes
at least a little bit with the pattern control. Doing this, both microphones
are pointed straight ahead.

M-S miking is a totally different thing. It's a stereo microphone technique
using a figure-8 pointed toward the side and an omni pointed straight ahead
(which would be anywhere if it were a perfect omni, but because real world
omnis aren't pefectly omni, it's 90' from the axis of the cardioid) and a
matrix to generate right and left channels. It's actually an attempt to
get the same pattern as a coincident cardioid pair, but with microphones
that are cleaner off-axis.
--scott


Scott,

My fault for not being clearer. I realize these are two different
things.

All I was meaning was:

If an MS array consisting of, say, a Beyer M160 hypercarioid and M130
figure-8 is reasonable - then an MS array consisting of a Schoeps 641
hypercardioid and Beyer M130 figure-8 isn't unreasonable, (provided of
course one accepts the differences in frequency response, sensitivity
and character between those two hypercardioids).

-Nick

[Scott Dorsey]

Nick Brown wrote:

If an MS array consisting of, say, a Beyer M160 hypercarioid and M130
figure-8 is reasonable - then an MS array consisting of a Schoeps 641
hypercardioid and Beyer M130 figure-8 isn't unreasonable, (provided of
course one accepts the differences in frequency response, sensitivity
and character between those two hypercardioids).

Yes. The problem that you get, though, is that the response between
the M and S mikes are radically different, so instruments of higher
pitch tend to move to the center of the soundstage. With high-pitched
instruments, you can hear them moving back and forth across the soundstage
with different notes.

That's why the M160 and M130 are designed to have very close frequency
responses. They are specifically designed to mate as an M-S pair.
--scott


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

[Roy W. Rising[_2_]]

(Scott Dorsey) wrote:
Nick Brown wrote:
Interesting point. So when the two are combined the result would be...
comb filtering?

Well, that always happens when you put two mikes together unless they are
in precisely the same place in space.

I'm not clear what you mean by "condensers and dynamics (pressure)" -
taken literally it would seem to imply that all condenser mics are
pressure operated, even the hypercardioid Schoeps under discussion here,
even the single-diaphram figure-8 condensers (Schoeps MK8, Sennheiser
MKH30). That can't be right, can it?

An omnidirectional microphone is sensitive to air pressure. A figure-8
microphone is sensitive to air velocity. Cardioids, hypercardioids, and
supercardioids are sensitive to both in varying degrees.

If combining air pressure and velocity information is inherently flawed,
wouldn't that flaw be manifest in every cardioid mic ever? I thought
that was how the cardioid pattern was formed.

Cardioid microphones are inherently flawed and will always have frequency
response that changes with direction. In general, the closer you get to
the edges of the spectrum (omni and figure-8), the better the off-axis
response will be.

Consequently if you compare the Schoeps cardioid and hypercardioid
capsules, you'll find the hypercardioid is actually cleaner off-axis than
the regular cardioid.

There are various tricks you can play to regularize the off-axis response
and some of them work better than others. Most microphone vendors use
a few of them.
--scott

I think this oversimplifies the pressure vs. velocity subject. I've just
reviewed Howard M. Tremaine's discussion of mics in his Audio Cyclopedia.
In *every* case he refers to ribbon-velocity mics as contrasted to pressure
responding condenser and dynamic types. However, he acknowledges there
certainly are bi-directional condenser mics ... without explanation.
Generally, directional patterns are accomplished by controlling the phase
of sound pressure reaching the back of the diaphragm. The Altec 639 summed
the outputs of forward facing dynamic and ribbon elements in one of the
very few attempts to use the 90 degree phase difference between pressure
and velocity.

On another note, the EV RE15 and RE20 are examples of directional mics with
*very* little frequency response change with respect to direction.

--
~
~ Roy
"If you notice the sound, it's wrong!"

[Chris Hornbeck]

On 22 Jul 2008 00:06:37 GMT, Roy W. Rising
wrote:

I think this oversimplifies the pressure vs. velocity subject. I've just
reviewed Howard M. Tremaine's discussion of mics in his Audio Cyclopedia.
In *every* case he refers to ribbon-velocity mics as contrasted to pressure
responding condenser and dynamic types. However, he acknowledges there
certainly are bi-directional condenser mics ... without explanation.
Generally, directional patterns are accomplished by controlling the phase
of sound pressure reaching the back of the diaphragm. The Altec 639 summed
the outputs of forward facing dynamic and ribbon elements in one of the
very few attempts to use the 90 degree phase difference between pressure
and velocity.

I think it's important to keep front-'n-center in mind
that radiation pattern depends *only* on how the diaphragm
is exposed to room air. Different generating mechanisms
affect this not a bit.

Of course, you're not suggesting otherwise, but a casual
reading by a newcomer might be misinterpreted.

Bitch, bitch, bitch...



Much thanks, as always,
Chris Hornbeck

[Scott Dorsey]

Roy W. Rising wrote:

I think this oversimplifies the pressure vs. velocity subject. I've just
reviewed Howard M. Tremaine's discussion of mics in his Audio Cyclopedia.
In *every* case he refers to ribbon-velocity mics as contrasted to pressure
responding condenser and dynamic types. However, he acknowledges there
certainly are bi-directional condenser mics ... without explanation.

Nope, it's not oversimplified at all. There are bidirectional ribbon
microphones, and they are velocity microphones. Imagine a microphone with
two diaphragms, one on either side of the cartridge, and a perforated
stator between them. Air blows in one direction, and one diaphragm is
pushed toward the stator, while another is pulled away from the stator.
The degree depends on how fast the air is moving and is independant of
the air pressure at the capsule. If the air pressure at the capsule
changes, both diaphragms move the same amount with respect to the stator.

Generally, directional patterns are accomplished by controlling the phase
of sound pressure reaching the back of the diaphragm. The Altec 639 summed
the outputs of forward facing dynamic and ribbon elements in one of the
very few attempts to use the 90 degree phase difference between pressure
and velocity.

Right, although again you can look at dual-diaphragm capsules as being
something different... they can be a pressure capsule if you look at
the charge between diaphragms, or a figure-8 capsule if you look at the
difference between the charge between each diaphragm and the stator.

You can use them as a cardioid by combining the two.

On another note, the EV RE15 and RE20 are examples of directional mics with
*very* little frequency response change with respect to direction.

They both employ some really ingenious tricks. Really, really ingenious.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Scott Dorsey wrote:
Roy W. Rising wrote:

I think this oversimplifies the pressure vs. velocity subject. I've just
reviewed Howard M. Tremaine's discussion of mics in his Audio Cyclopedia.
In *every* case he refers to ribbon-velocity mics as contrasted to pressure
responding condenser and dynamic types. However, he acknowledges there
certainly are bi-directional condenser mics ... without explanation.

Nope, it's not oversimplified at all. There are bidirectional ribbon
microphones, and they are velocity microphones.

Yeesh. I mean bidirectional condenser microphones.
--scott

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