Mixing a Stereo Recording

[Nathan]

Hi all,

I've been doing some stereo recording of acoustic guitar. Sometimes I
also record vocals at the same time. In all I use 3 mics, 2 for
guitar, one for vocals. I've tried 4, but to minimize phase problems
I've cut it down to 3. I've tried various mic techniques and have
gotten comfortable with the use of them. My favorite mic placement is
a spaced pair with a vocal mic raised up in line with the mouth above
the spaced pair. I've experimented with the distance from the guitar
and vocal a lot. I spend a lot of time trying different placements
and patterns. My other favorite is Blumlein. This is much easier to
mix but it's not quite the sound I'm going for, I prefer the spaced
pair with a vocal mic. I found this is the hardest placement to get
right though.

The part where I'd like to know more about is the mixing after laying
the tracks down. How does the mixing differ for different techniques
and mic patterns? What I know so far is what I've learned from
various articles and from experimenting on my own.

Could anyone recommend a good book or video series that deals
specifically with stereo mixing? I've having a difficult time finding
anything, whether it's a book or video on the subject. Most of what I
found deals with mixing with multiple mono sources or stereo mic
placement. I need something on stereo mixing and all the intricacies
of it.

In particular I'd like to get an experienced engineer's recommendation
on how to deal with phase issues, how and when to use delay, panning
techniques, eq, plugins, all when dealing with a stereo source in
particular. When working with sources that have been recorded with
different mic placements, how do you deal with that in the mixing
stage. I purchased a video guide for singer songwriter mixing but it
didn't delve into mixing stereo at all. It was useful for equalizing
and compression, but I was looking for something more thorough and
comprehensive.

Could you give me some recommendations please? I use Cubase 4 by the
way.

[Peter Larsen[_3_]]

Nathan wrote:

| Hi all,

|| I've been doing some stereo recording of acoustic guitar.

Close pair + distant pair is likely to work very well.

| Sometimes I also record vocals at the same time.

Good for the syncronicity, bad for separation, use a mic very close to the
mouth so that at least that part of it is clean. Read up on how to deploy
fig8's close to the guitar for max separation, the standard advice seems to
be to about using one.

| In all I use 3 mics, 2 for
| guitar, one for vocals. I've tried 4, but to minimize phase problems
| I've cut it down to 3.

You ARE allowed to solve comb filtering issues by giving the guitar track a
8 milliseconds offset afterwards or perhaps even more.

| much easier to mix but it's not quite the sound I'm going for, I
| prefer the spaced pair with a vocal mic. I found this is the
| hardest placement to get right though.

Close pair: ortf, distant pair A-B, ie. spaced.

| In particular I'd like to get an experienced engineer's
| recommendation on how to deal with phase issues, how and when to use
| delay, panning techniques, eq, plugins, all when dealing with a
| stereo source in particular.

Keep it simple lest the audio gets confused and the musicality lost.

| When working with sources that have
| been recorded with different mic placements, how do you deal with
| that in the mixing stage. I purchased a video guide for singer
| songwriter mixing but it didn't delve into mixing stereo at all.

Hardly anybody can mic stereo these days and most certainly not the average
basement studio track builder. What you need to get to work for you is to
have the close as well as the distant pair provide usable good ambience on
vox because whatever you do you WILL have lots of vox in them. Sliding the
tracks in time is what I would try first, the distant pair is probably ok,
but you need to move the close pair about halfway out to where the distant
pair is IN TIME, not physically. One millisecond pr. foot is exact enough,
for a starter try sliding the close pair 8 milliseconds and the distant pair
8 milliseconds (to preserve the relationship) and perhaps you will end up
with a layering that is "just right" ... or perhaps not. You'll be the first
to know.

Yes, there are known logic inconsistencies in the above, I left them in by
design .... you have to listen for what sounds right. Good sound enginering
starts with making good stereo recordings .... lotsa people don't even know
that stereo is not something that is done with a panpot.

Kind regards

Peter Larsen

[Nathan]

On Jun 18, 1:32*am, "Soundhaspriority" > wrote:
> "Nathan" > wrote in message
>
> ...
>
> > Hi all,
>
> > I've been doing some stereo recording of acoustic guitar. *Sometimes I
> > also record vocals at the same time. *In all I use 3 mics, 2 for
> > guitar, one for vocals. *I've tried 4, but to minimize phase problems
> > I've cut it down to 3. *I've tried various mic techniques and have
> > gotten comfortable with the use of them. *My favorite mic placement is
> > a spaced pair with a vocal mic raised up in line with the mouth above
> > the spaced pair. *I've experimented with the distance from the guitar
> > and vocal a lot. *I spend a lot of time trying different placements
> > and patterns. *My other favorite is Blumlein. *This is much easier to
> > mix but it's not quite the sound I'm going for, I prefer the spaced
> > pair with a vocal mic. *I found this is the hardest placement to get
> > right though.
>
> > The part where I'd like to know more about is the mixing after laying
> > the tracks down. *How does the mixing differ for different techniques
> > and mic patterns? *What I know so far is what I've learned from
> > various articles and from experimenting on my own.
>
> > Could anyone recommend a good book or video series that deals
> > specifically with stereo mixing? *I've having a difficult time finding
> > anything, whether it's a book or video on the subject. *Most of what I
> > found deals with mixing with multiple mono sources or stereo mic
> > placement. *I need something on stereo mixing and all the intricacies
> > of it.
>
> > In particular I'd like to get an experienced engineer's recommendation
> > on how to deal with phase issues, how and when to use delay, panning
> > techniques, eq, plugins, all when dealing with a stereo source in
> > particular. *When working with sources that have been recorded with
> > different mic placements, how do you deal with that in the mixing
> > stage. *I purchased a video guide for singer songwriter mixing but it
> > didn't delve into mixing stereo at all. *It was useful for equalizing
> > and compression, but I was looking for something more thorough and
> > comprehensive.
>
> > Could you give me some recommendations please? *I use Cubase 4 by the
> > way.
>
> Nathan, the only reason I'm responding to this is, no one else has. There
> are masters of technique in this group, but perhaps they have gotten tired.
> Questions such as yours require a lot of words to say that there is no
> satisfactory answer. The experts mix intuitively, according to what they
> hear. They may not have ways of putting what they do into words.
>
> The spaced mike technique doesn't have scientific answers because of phase
> problems, destructive cancellation (comb filteirng), room reflections, time
> delay, and crosstalk. It sounds simple, but it is not. There are literally
> no guidelines for it. Some experts used spaced pairs, but they work it by
> ear. At the current time, there are "formulas", or prescriptions, for
> "coincident pair" techniques, but not spaced techniques. In fact, the
> Blumlein technique that is your favorite has a known exact correspondence to
> a stereo pair of speakers. None of the other coincident techniuqes have that
> exact correspondence.
>
> Bob Morein
> (310) 237-6511

I am a bit shocked that there are no guides out there for this
subject. Stereo has been around for many years now, it seems somehow
unreal to me. With the explosion of home/project studios you'd think
there would be a larger market for it. Seems like an opportunity for
an expert inclined to teaching.

But then again, I can see first hand how deceptively simple it looks
on the surface and how intricate this can be when you actually delve
into it and all the factors come together... it can be overwhelming
for a novice. Probably most would abandon the idea and just go back
to mono. But... I'm stubborn, and I'm curious about this. When you
nail it just right, stereo blows away mono, so its worth it for me. I
think understanding phase and time relationships between sources is
crucial for stereo. So I will read more about that and try to make a
more scientific approach to this.

I'm also going to get some good guides on standard mixing and try to
apply it to stereo. Thanks all the same for your replies and helpful
advice.

[Nathan]

On Jun 19, 12:12*am, "Peter Larsen" > wrote:
> Nathan wrote:
>
> | Hi all,
>
> || I've been doing some stereo recording of acoustic guitar.
>
> Close pair + distant pair is likely to work very well.
>
> | Sometimes I also record vocals at the same time.
>
> Good for the syncronicity, bad for separation, use a mic very close to the
> mouth so that at least that part of it is clean. Read up on how to deploy
> fig8's close to the guitar for max separation, the standard advice seems to
> be to about using one.
>
> | *In all I use 3 mics, 2 for
> | guitar, one for vocals. *I've tried 4, but to minimize phase problems
> | I've cut it down to 3.
>
> You ARE allowed to solve comb filtering issues by giving the guitar track a
> 8 milliseconds offset afterwards or perhaps even more.
>
> | much easier to mix but it's not quite the sound I'm going for, I
> | prefer the spaced pair with a vocal mic. *I found this is the
> | hardest placement to get right though.
>
> Close pair: ortf, distant pair A-B, ie. spaced.
>
> | In particular I'd like to get an experienced engineer's
> | recommendation on how to deal with phase issues, how and when to use
> | delay, panning techniques, eq, plugins, all when dealing with a
> | stereo source in particular.
>
> Keep it simple lest the audio gets confused and the musicality lost.
>
> | When working with sources that have
> | been recorded with different mic placements, how do you deal with
> | that in the mixing stage. *I purchased a video guide for singer
> | songwriter mixing but it didn't delve into mixing stereo at all.
>
> Hardly anybody can mic stereo these days and most certainly not the average
> basement studio track builder. What you need to get to work for you is to
> have the close as well as the distant pair provide usable good ambience on
> vox because whatever you do you WILL have lots of vox in them. Sliding the
> tracks in time is what I would try first, the distant pair is probably ok,
> but you need to move the close pair about halfway out to where the distant
> pair is IN TIME, not physically. One millisecond pr. foot is exact enough,
> for a starter try sliding the close pair 8 milliseconds and the distant pair
> 8 milliseconds (to preserve the relationship) and perhaps you will end up
> with a layering that is "just right" ... or perhaps not. You'll be the first
> to know.
>
> Yes, there are known logic inconsistencies in the above, I left them in by
> design .... you have to listen for what sounds right. Good sound enginering
> starts with making good stereo recordings .... lotsa people don't even know
> that stereo is not something that is done with a panpot.
>
> * * Kind regards
>
> * * Peter Larsen


"You ARE allowed to solve comb filtering issues by giving the guitar
track a
8 milliseconds offset afterwards or perhaps even more. "

Ok I will try 8 ms thanks. I've been experimenting with very small
delays, like .01 to .30 ms in Cubase.

"Hardly anybody can mic stereo these days and most certainly not the
average
basement studio track builder. What you need to get to work for you is
to
have the close as well as the distant pair provide usable good
ambience on
vox because whatever you do you WILL have lots of vox in them. Sliding
the
tracks in time is what I would try first, the distant pair is probably
ok,
but you need to move the close pair about halfway out to where the
distant
pair is IN TIME, not physically. One millisecond pr. foot is exact
enough,
for a starter try sliding the close pair 8 milliseconds and the
distant pair
8 milliseconds (to preserve the relationship) and perhaps you will end
up
with a layering that is "just right" ... or perhaps not. You'll be the
first
to know. "

Great thanks for that guide Peter. I will give that a shot.

[Scott Dorsey]

Nathan > wrote:
>I am a bit shocked that there are no guides out there for this
>subject. Stereo has been around for many years now, it seems somehow
>unreal to me. With the explosion of home/project studios you'd think
>there would be a larger market for it. Seems like an opportunity for
>an expert inclined to teaching.

Approach one:

Start with ambient mikes. Bring everything else up to fit into the
sound of the ambient mikes. If delay or EQ is needed, adjust the
spot mike tracks and not the ambient tracks.

Approach two:

Start out with the thing that is most important in the recording.
If it's a song, that's the lead vocal. If it's a classical guitar
recording, it's the guitar. Find the thing that is important in the
recording, and bring it up. Make it sound good. THEN, bring in
the rest of the tracks one at a time. EQ and/or delay them so that
they fit into what is left by the thing that is most important.

The thing that is most important varies considerably from one genre
to another, but it is never, never the kick drum.

Once you start adding in spot mikes and panpotting things around for
intensity stereo, your real stereo image becomes badly corrupted.
Life's just like that, don't worry about it. Place things in the
sound field where they don't interfere with one another. Occasionally
switch the monitor panel to mono and listen to what the track sounds
like in mono.... if there are dramatic changes when you go to mono,
you've got a problem. and you can either reduce phase differences
between channel with delays or by using different panning and dropping
stereo tracks, or you can just issue seperate stereo and mono mixes
for radio play.

>But then again, I can see first hand how deceptively simple it looks
>on the surface and how intricate this can be when you actually delve
>into it and all the factors come together... it can be overwhelming
>for a novice. Probably most would abandon the idea and just go back
>to mono. But... I'm stubborn, and I'm curious about this. When you
>nail it just right, stereo blows away mono, so its worth it for me. I
>think understanding phase and time relationships between sources is
>crucial for stereo. So I will read more about that and try to make a
>more scientific approach to this.

When you close-mike a guitar with two mikes, what you get isn't stereo
and doesn't really bear much connection with real stereo, because you
aren't reproducing an actual "solid" stereo image. That's fine, because
multitrack production is all about artificial environments and most
listeners today will have never heard real stereo anyway.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Larsen[_3_]]

Nathan wrote:

| On Jun 18, 1:32 am, "Soundhaspriority" > wrote:

|| The spaced mike technique doesn't have scientific answers ...

Flat wrong, one theory covers all variations of a mic pair, again that 1983
paper, a new version is out for quad, have yet to find and read it. But for
the Questionee the stereo version is required reading. For you too
apparently. It does not replace listening, but it makes it easier for the
novice to find the square meter to look for the proper placement of the mic
stand on and to adapt l-r mic distance and angling to the distance to and
width of the stage. Covers omni pairs as well as cardioid pairs.

| I am a bit shocked that there are no guides out there for this
| subject.

Referred to above, one theory and one explanation that covers all mic pairs.

| I'm also going to get some good guides on standard mixing and try to
| apply it to stereo.

For a simple guideline the mic to audio source distance to start with is
comparable to the size magnitude o the sound source. Combine that with
keeping the distance to what you do not want to record with a mic(pair)
three times larger than the distance to what you do want to record and you
have a good starting point.

Kind regards

Peter Larsen

[Mike Rivers]

Nathan wrote:

> I am a bit shocked that there are no guides out there for this
> subject. Stereo has been around for many years now, it seems somehow
> unreal to me. With the explosion of home/project studios you'd think
> there would be a larger market for it. Seems like an opportunity for
> an expert inclined to teaching.

There's a certain amount of science involved, but it's mostly art. You
don't learn
how to carve a stone elephant by reading a book, you just cut away
everything
that doesn't look like an elephant.

Understanding the science will help you to recognize what you're hearing,
but first you have to hear it, and that comes from listening and
fiddling around
to see how things interact.

One good book that pretty much covers it all is Total Recording by David
Moulton. It looks and reads like the text book for a one year college course
in recording arts, and maybe it is. You don't hear much about it because
it's
not a quick fix, nor is it inexpensive.

http://www.kiqproductions.com



--
If you e-mail me and it bounces, use your secret decoder ring and reach
me here:
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Nathan]

On Jun 20, 4:24*pm, "Soundhaspriority" > wrote:
> "Peter Larsen" > wrote in message
>
> ...
>
> > Nathan wrote:
>
> > | On Jun 18, 1:32 am, "Soundhaspriority" > wrote:
>
> > || The spaced mike technique doesn't have scientific answers ...
>
> > Flat wrong, one theory covers all variations of a mic pair, again that
> > 1983 paper, a new version is out for quad, have yet to find and read it..
> > But for the Questionee the stereo version is required reading. For you too
> > apparently.
>
> You are flat wrong, Peter. The paper,http://www.microphone-data.com/pdfs/Stereo%20zoom.pdf,
>
> covers spacing out to 50cm, no further. Apparently, you need to read it
> also.
>
> Kind regards,
> Bob Morein
> (310) 237-6511

Thanks again for the great info. I've printed that article out for
reading.

I did some more tests. I've set up a spaced pair, the length of the
guitar away from me. The height of the spaced pair is just slightly
below the sound hole level of the guitar. I've then set up a vocal
mic about a foot away, mouth level, tilted slightly up away from the
guitar. All mics are cardioid.

When I pan the right and left guitar mics I get no noticeable
interference. However when I add the vocal mic in I do hear some
destructive interference going on. What I've done is delayed it
about .23 ms. Might it be better to go the other way, say move it
ahead in time if it's the lead vocal to -.23 ms? It does seem better
with just this slight delay.

Looking at this section in Wiki about Constructive and Destructive
interference:

http://en.wikipedia.org/wiki/Destructive_interference#Constructive_and_destruct ive_interference

My other question is; if the peaks from the different sources lining
up causes amplitude and if the peaks from say the vocal mic lining up
with a peak from the guitar mic causes cancellation, then would
directly between these points be considered the theoretical "sweet
spot"? In theory, how should a well combined set of waves overlap?

I'm wondering if there are tools/programs to analyze and compare two
or more waves to determine, if combined, where the theoretical sweet
spot would be. The program would compare the two waves and determine
where the least cancellation and amplitude is occurring. Output would
be the amount of delay in ms to shift the wave to minimize
interference. Does anyone know if there is a program that does that?

Thanks,
Nathan

[Scott Dorsey]

Nathan > wrote:
>
>I did some more tests. I've set up a spaced pair, the length of the
>guitar away from me. The height of the spaced pair is just slightly
>below the sound hole level of the guitar. I've then set up a vocal
>mic about a foot away, mouth level, tilted slightly up away from the
>guitar. All mics are cardioid.

This isn't stereo. It might give you an interesting and useful sound
when you play it back on a stereo recorder, but it's not stereo.

>When I pan the right and left guitar mics I get no noticeable
>interference. However when I add the vocal mic in I do hear some
>destructive interference going on. What I've done is delayed it
>about .23 ms. Might it be better to go the other way, say move it
>ahead in time if it's the lead vocal to -.23 ms? It does seem better
>with just this slight delay.

Do you hear the interference on the vocal or on the guitar?

If you're trying to record vocal and guitar at the same time, the
real key to that is usually keeping the guitar out of the vocal
mike. Delay will help, but there's only so much you can do since
you are also picking up room tone which is seemingly random in
delay since it's coming from many different paths.

>My other question is; if the peaks from the different sources lining
>up causes amplitude and if the peaks from say the vocal mic lining up
>with a peak from the guitar mic causes cancellation, then would
>directly between these points be considered the theoretical "sweet
>spot"? In theory, how should a well combined set of waves overlap?

The cancellation nodes and peaks vary with frequency. That's why you
get that "phasey" sound... it's due to comb filtering. You can't eliminate
it, you can only change it so it's less offensive.
--scott

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

[Mike Rivers]

Nathan wrote:

> I did some more tests. I've set up a spaced pair, the length of the
> guitar away from me. The height of the spaced pair is just slightly
> below the sound hole level of the guitar. I've then set up a vocal
> mic about a foot away, mouth level, tilted slightly up away from the
> guitar. All mics are cardioid.
>
> When I pan the right and left guitar mics I get no noticeable
> interference. However when I add the vocal mic in I do hear some
> destructive interference going on. What I've done is delayed it
> about .23 ms. Might it be better to go the other way, say move it
> ahead in time if it's the lead vocal to -.23 ms? It does seem better
> with just this slight delay.

0.23 ms is a pretty small delay, about the equivalent of 3 inches
difference in the distance between mics. The comb filtering due
to summing the outputs would start at a fairly high frequency, However,
that's in the range where the precedence effect can be heard. This
is that effect that makes what arrives at our ears first seem loudest.
So that might be helping you to get a better mix.

> My other question is; if the peaks from the different sources lining
> up causes amplitude and if the peaks from say the vocal mic lining up
> with a peak from the guitar mic causes cancellation, then would
> directly between these points be considered the theoretical "sweet
> spot"? In theory, how should a well combined set of waves overlap?

With a complex waveform which includes both harmonics of the source
and reflections, you really can't ever tell because you can't get everything
perfectly lined up. Generally when we "line up" things, for instance a
direct output from a guitar pickup and the output from a microphone on
the guitar amplifier's speaker, or the snare mic and the snare in the drum
overhead mics, we line up the initial attacks so that they're going in the
same direction. If this means delaying one by half a cycle, that's what we
do (or maybe just invert the signal). That's usually what works best.
That's "constructive" interference - where what we hear most of is
reinforced.

> I'm wondering if there are tools/programs to analyze and compare two
> or more waves to determine, if combined, where the theoretical sweet
> spot would be.

It depends on how you define "sweet spot." Sometimes things sound better
with certain frequencies boosted, sometimes with certain frequencies
attenuated. The best tool is your ears. The second best tool is a tape
measure,
though in this digital age I suppose it's also necessary to understand the
delays present in the signal path and, if they're not identical for
every signal,
throw the differences into the equation.

> The program would compare the two waves and determine
> where the least cancellation and amplitude is occurring.

You can do that simply by summing them and listening as you adjust
the delay in small increments. It's usually easier to hear if you invert
one before summing and listen for the best null. As I said, with a
complex waveform, you'll never get a perfect null. You might get some
better insight into this if you repeat your test setup and put a loudspeaker
in place of your guitar, or your voice, or somewhere in between, and feed
it with a single frequency (sine wave). Sweep the frequency and then
listen to what happens.



--
If you e-mail me and it bounces, use your secret decoder ring and reach
me here:
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Peter Larsen[_3_]]

Nathan wrote:

[quoting one of the Moreins, probably the real one]

| You are flat wrong, Peter. The
| paper,http://www.microphone-data.com/pdfs/Stereo%20zoom.pdf,
|
| covers spacing out to 50cm, no further.

That is as far as it provides values, it also does not provide values for
negative angle between directional microphones, but the principle still
applies and negative angle, ie. toe-in, between directional microphones has
worked fine for me when miking up an organ with that being the only
logistically possible miking-up option.

| Apparently, you need to read also.

Did that - have a protractor made by a friend of mine - give it some more
Bob, try the options and then forget it and just set the mics up
understanding the principles.

| Bob Morein

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Nathan wrote:

| On Jun 20, 4:24 pm, "Soundhaspriority" > wrote:
| When I pan the right and left guitar mics I get no noticeable
| interference. However when I add the vocal mic in I do hear some
| destructive interference going on. What I've done is delayed it
| about .23 ms. Might it be better to go the other way, say move it
| ahead in time if it's the lead vocal to -.23 ms? It does seem better
| with just this slight delay.

One millisecond of delay equals one foot of distance.

You also need to see this in a wavelength context. 8 milliseconds is more
"like it" because it pushes the probable 6 dB dip caused by the multiple
pathways to the low midrange where it is less audible and may be compensated
for by room tone.

| Nathan

Kind regards

Peter Larsen

[Nathan]

On Jun 22, 11:11*am, "Peter Larsen" > wrote:
> Nathan wrote:
>
> | On Jun 20, 4:24 pm, "Soundhaspriority" > wrote:
> | When I pan the right and left guitar mics I get no noticeable
> | interference. *However when I add the vocal mic in I do hear some
> | destructive interference going on. *What I've done is delayed it
> | about .23 ms. *Might it be better to go the other way, say move it
> | ahead in time if it's the lead vocal to -.23 ms? *It does seem better
> | with just this slight delay.
>
> One millisecond of delay equals one foot of distance.
>
> You also need to see this in a wavelength context. 8 milliseconds is more
> "like it" because it pushes the probable 6 dB dip caused by the multiple
> pathways to the low midrange where it is less audible and may be compensated
> for by room tone.
>
> | Nathan
>
> * Kind regards
>
> * Peter Larsen

Thanks guys, your responses have given me a large chunk of new info to
chew on for a while.

What constitutes stereo? Is true stereo only achieved when you have
the full stereo image captured with 2 microphones? Once you insert a
third mic, is it no longer considered "true" stereo because the stereo
image has been defiled? lol What about 4 mics, one pair close up and
the second pair more ambient?

Also, I was wondering about this phase program/plugin I've been trying
from Voxengo called PHA979.

http://www.voxengo.com/product/pha979/

I've tried it and it is effective in some cases where like in the
example I gave, the voice source is interfering with the stereo pair
source. A new version just came out that I'm going to try, it looks
more tweakable. But before I go about messing with the phase I want
to understand better what exactly I'm doing.

I was a bit confused about phase shift. I was thinking phase shift
was a form of delay, but I wasn't understanding the full concept. If
that was true we would just have delay and phase would fall into the
category of delay. I'm still not understanding it fully so I will
keep reading about it. I found this site helpful:

http://www.libinst.com/tpfd.htm


Thanks,
Nathan

[Nathan]

On Jun 22, 2:45*pm, Nathan > wrote:
> On Jun 22, 11:11*am, "Peter Larsen" > wrote:
>
>
>
> > Nathan wrote:
>
> > | On Jun 20, 4:24 pm, "Soundhaspriority" > wrote:
> > | When I pan the right and left guitar mics I get no noticeable
> > | interference. *However when I add the vocal mic in I do hear some
> > | destructive interference going on. *What I've done is delayed it
> > | about .23 ms. *Might it be better to go the other way, say move it
> > | ahead in time if it's the lead vocal to -.23 ms? *It does seem better
> > | with just this slight delay.
>
> > One millisecond of delay equals one foot of distance.
>
> > You also need to see this in a wavelength context. 8 milliseconds is more
> > "like it" because it pushes the probable 6 dB dip caused by the multiple
> > pathways to the low midrange where it is less audible and may be compensated
> > for by room tone.
>
> > | Nathan
>
> > * Kind regards
>
> > * Peter Larsen
>
> Thanks guys, your responses have given me a large chunk of new info to
> chew on for a while.
>
> What constitutes stereo? *Is true stereo only achieved when you have
> the full stereo image captured with 2 microphones? *Once you insert a
> third mic, is it no longer considered "true" stereo because the stereo
> image has been defiled? lol *What about 4 mics, one pair close up and
> the second pair more ambient?
>
> Also, I was wondering about this phase program/plugin I've been trying
> from Voxengo called PHA979.
>
> http://www.voxengo.com/product/pha979/
>
> I've tried it and it is effective in some cases where like in the
> example I gave, the voice source is interfering with the stereo pair
> source. *A new version just came out that I'm going to try, it looks
> more tweakable. *But before I go about messing with the phase I want
> to understand better what exactly I'm doing.
>
> I was a bit confused about phase shift. *I was thinking phase shift
> was a form of delay, but I wasn't understanding the full concept. *If
> that was true we would just have delay and phase would fall into the
> category of delay. *I'm still not understanding it fully so I will
> keep reading about it. *I found this site helpful:
>
> http://www.libinst.com/tpfd.htm
>
> Thanks,
> Nathan

These are also very good:

http://www.indiana.edu/~emusic/acoustics/phase.htm

http://www.youtube.com/watch?v=A9098KMP_Q8

[Scott Dorsey]

Nathan > wrote:
>
>What constitutes stereo? Is true stereo only achieved when you have
>the full stereo image captured with 2 microphones? Once you insert a
>third mic, is it no longer considered "true" stereo because the stereo
>image has been defiled? lol

There is a good tutorial on introductory stereophony and stereo miking
technique on josephson.com.

>I was a bit confused about phase shift. I was thinking phase shift
>was a form of delay, but I wasn't understanding the full concept. If
>that was true we would just have delay and phase would fall into the
>category of delay. I'm still not understanding it fully so I will
>keep reading about it. I found this site helpful:

"Delay" is constant time for all frequencies. "Group delay" time varies with
frequency.
--scott

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

[Peter Larsen[_3_]]

Nathan wrote:

| Also, I was wondering about this phase program/plugin I've been trying
| from Voxengo called PHA979.

| http://www.voxengo.com/product/pha979/

| I've tried it and it is effective in some cases where like in the
| example I gave, the voice source is interfering with the stereo pair
| source. A new version just came out that I'm going to try, it looks
| more tweakable. But before I go about messing with the phase I want
| to understand better what exactly I'm doing.

That is when you get to chop the audio up and do things with it in short
segments. Audition 3 has a phase correction tool, I tried it on a spot mike
at a wind instrument concert event with a violin player doing one solo
instruments and a concerto for basset horn and clarinet. It was excellent on
the speaker, it was however decided that the speak should not go on the
recording and not really bad on the violin, possibly an improvement or
possibly not .... violins do strange things and radiate sounds in may ways,
directions and polarities. I might have settled for doing it because of the
spatial improvement it gave. And then I started listening to what it did to
the clarinet, it was sheer and gruesome sonic disaster because long
continuous tones ended sounding chopped up and "flutterized".

| I was a bit confused about phase shift. I was thinking phase shift
| was a form of delay, but I wasn't understanding the full concept. If
| that was true we would just have delay and phase would fall into the
| category of delay. I'm still not understanding it fully so I will
| keep reading about it. I found this site helpful:

| http://www.libinst.com/tpfd.htm

I'l leave that to Scott, he is better at explaining this than I can ever
dream of getting.

| Thanks,
| Nathan

Kind regards

Peter Larsen

[William Sommerwerck]

> What constitutes stereo? Is true stereo only achieved when
> you have the full stereo image captured with 2 microphones?
> Once you insert a third mic, is it no longer considered "true"
> stereo because the stereo image has been defiled? lol
> What about 4 mics, one pair close up and the second pair
> more ambient?

"Stereo" is a Greek prefix meaning "solid" -- as in stereoscopic: "'House of
Wax' was one of the first modern stereoscopic films."

With respect to sound recordings, the word's implication is that one hears a
three-dimensional image that includes both width and depth, and (hopefully)
the relationship of each instrument to the hall's acoustics.

So... A multi-miked and pan-potted recording, no matter how many channels,
is not, in the proper meaning of the word, "stereo".

[Ron Capik[_2_]]

> < ...snip... >
> With respect to sound recordings, the word's implication is that one hears a
> three-dimensional image that includes both width and depth, and (hopefully)
> the relationship of each instrument to the hall's acoustics.
>
> So... A multi-miked and pan-potted recording, no matter how many channels,
> is not, in the proper meaning of the word, "stereo".
>
>
In truth one may invent a virtual sound space from a pan-
potted recording that may provide a "proper" virtual stereo
"sound stage" image.
[See "Physics Today" June 2009: Auralization of spaces.]

However, it ain't easy.



Later...

Ron Capik
--