I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

caveplayer wrote:
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.

This is a reasonable ballpark for placement of microphones that are being
summed to mono, where you don't want cancellation between them. It has
_nothing_ to do with XY stereo. With typical cardioid microphones summed
to mono, this is about the point where cancellation effects start being
noticed.

With tighter microphones, you can get farther away before it's a problem.
With wider microphones, you can't get as far away.

Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.

But you are using those as a stereo pair. They aren't being summed to
mono, they are being panned wide. So cancellation isn't an issue at all.

I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)

No, you can try an ORTF pair to begin with. If it's too wide, move
the mikes in. If it's too narrow, you can pull them out.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 6 Oct 2004 06:23:22 -0700, (caveplayer) wrote:

I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.

This is confusing, but I think you're confusing two different
things. Let me see if I can straighten this out without too many
people correcting me.
X-Y is when you have the mics pointing different directions but
they are crossing at the elements, and used to make a stereo recording
(one mic is left channel, the other the right channe, and they're both
the same level). The elements are at the same point (or as close as
possible) but since they're directional, they pick up different sounds
from the same point in space. Among other things, this gives good mono
compatibility.
The 3-to-1 rule applies when using each mic to pick up the sound of
a different instrument. If you have mic A picking up instrument A two
feet away, you should have mic B (picking up someothing else) at least
six feet away from instrument A (or is it mic A?). This is so that
when they are mixed together (this is different from X-Y in that the
level of each mic is used to adjust the volume of each instrument in
the final mix) there's not as much comb filtering caused by the same
signal coming through both mics, one delayed more than the other. As I
understand it, it's hoped that the distance reduces the volume in the
other mic enough that comb filtering doesn't become a big problem.

Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart?

No, that would be if each mic were to pick up a different
instrument. For this, you definitely want the mics together.

And if so
where do i point them.

Try them at about 90 degrees, one pointing 45 degrees to the left,
the other pointing 45 degrees to the right. Try adjusting the angle
(keeping the bisected angle pointing at the guitar) as well as the
distance to the guitar to see how much room tone and stereo spread you
get.
Someone makes a "stereo bar" that you can get to put both mics on
one stand for X-Y and similar stereo applications.

(you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)

Not only do we not kick people off (that's hard to do on Usenet),
we try to be nice to people asking legitimate, on-topic questions
(this seems to be less common thesedays), regardless of knowledge
level. But welcome to Usenet anyway.

thanks

-----
http://mindspring.com/~benbradley

6 Oct 2004 06:23:22 -0700, suggested:
: I've heard the rule of thumb for x-y configuration is that the ratio
: of distance between mics to distance from instrument should be about 3
: to 1.

I think you're mixing up your rules. In an x-y stereo configurationn the
capsules should be as close together as possible, and for cardioids they
should be positioned at a 90-degree angle from each other, with the center
of the source in between them.

The 3 to 1 rule is to avoid phase cancellation between sources on the
*same channel*, so it doesn't apply to a two-mic stereo configuration,
with the possible exception of A-B stereo, and then only if you want your
recording to be mono-compatible. In coincident pair stereo configurations,
recordings should always be mono-compatible because there is negligeable
phase-cancellation when the two capsules are in essentially the same
physical location.

--
agreenbu @ nyx . net andrew michael greenburg

If I have this right-
The three to one rule is to avoid phase cancellation
between mics and does not apply to X-Y configurations.
I originally heard of the three to one rule in Lou Burroughs book-
Microphone Design and Application

caveplayer wrote:

I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

"andrewunix" wrote in message
...
6 Oct 2004 06:23:22 -0700, suggested:

I think you're mixing up your rules. In an x-y stereo configurationn the
capsules should be as close together as possible, and for cardioids they
should be positioned at a 90-degree angle from each other, with the center
of the source in between them.

Actually the classic XY or ORTF configurations using cardioid microphones
angle them at 110 degrees. With hypercardioids you'd start at 90 degrees.
Vary either angle as needed (there's been another thread on that going for a
couple of weeks now).

Peace,
Paul

Joe Boerst wrote:
The three to one rule is to avoid phase cancellation
between mics and does not apply to X-Y configurations.
I originally heard of the three to one rule in Lou Burroughs
book Microphone Design and Application


The Fig. of Lou Burroughs are here to see:
http://www.sengpielaudio.com/Die3zu1Regel.pdf
The topic is: The 3:1 rule for mic setup for pop recording.
That is to show that this has nothing to do with a main
X/Y-microphone. The rule is only for multi micing.
Look at the smoother frequency response when you
use microphone 4 or 5 in connection with mic 1.

Eberhard Sengpiel
German forum for microphone recordings
and sound studio techniques
http://www.sengpielaudio.com

(caveplayer) wrote in message . com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

You're getting two different mic techniques mixed up. XY is a
coincident technique (usually) involving two directional (such as
cardioid) mics crossed at (about) 90 degrees, with the two capsules
either right next to or right over one another. This way, wherever the
sounds originate, they arrive at both capsules simultaneously. Thus,
for your setup, you would simply place the pair of mics at 3 to 4 feet
away from your instrument. This seems a little close, however. I'd
suggest experimenting with this distance, depending on how good the
room or stage sounds.

The "3 to 1" rule is when using close single mics on several
instruments. The reason for this is to avoid phasing problems when
more than one mic picks up the same instrument. By having the intended
mic 3x closer to an instrument than the mics used for other
instruments, the bleed is far enough down that phasing problems are
minimized.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

As I understand it, this rule doesn't apply to X-Y or any other
coincident pair technique. It's a rule of thumb for multiple mic
situations where you are trying to keep phase problems from occuring
between mics which are set to pick up different sources and there is
some bleed in each from the source they are not meant to pick up. It's
really only relevant for controlling the sound of bleed when the mics
are mixed together. If you have, say, two mics on one guitar cab and
are mixing them together at close to the same level, the 3 to 1 rule
is not relevant.


(caveplayer) wrote in message . com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

(caveplayer) wrote in message . com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

They won't kick you off! Hell, you seem all right to me.
But I believe when you used the term "x-y configuration," you actually
described what is commonly referred to as a "stereo pair."

http://www.soundonsound.com/sos/1997...reomiking.html

Others more knowledgeable than I on these matters will perhaps discuss
the relative merits of coincident techniques vs. space pair mics for
your specific application.

In article writes:

The 3-to-1 rule applies when using each mic to pick up the sound of
a different instrument. If you have mic A picking up instrument A two
feet away, you should have mic B (picking up someothing else) at least
six feet away from instrument A (or is it mic A?).

Yes. The "3-to-1 rule" applies to the spacing between mics, not
between Mic 1 and Source 1 and Mic 2 and Source 1. Further, it's
really officially only for omni mics. You can put directional mics
closer together.


--
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 he double-m-eleven-double-zero at yahoo

Wed, 06 Oct 2004 16:26:05 GMT, suggested:
:
: "andrewunix" wrote in message
: ...
: 6 Oct 2004 06:23:22 -0700, suggested:
:
: I think you're mixing up your rules. In an x-y stereo configurationn the
: capsules should be as close together as possible, and for cardioids they
: should be positioned at a 90-degree angle from each other, with the center
: of the source in between them.
:
: Actually the classic XY or ORTF configurations using cardioid microphones
: angle them at 110 degrees. With hypercardioids you'd start at 90 degrees.
: Vary either angle as needed (there's been another thread on that going for a
: couple of weeks now).

Ah, I always get that confused. Thanks for the clarification.

--
agreenbu @ nyx . net andrew michael greenburg

Ben Bradley wrote in message . ..
On 6 Oct 2004 06:23:22 -0700, (caveplayer) wrote:

Yes I know. that was just a typo. I realized just after i posted. I
meant to say spaced pair. I read about these basic setups from Harmony
Central, a guitar website. They do suggest, and even show a picture,
using spaced pair for a single guitar. I tried the X-Y and yes, it
does produce good mono. You can tell especially by panning and seeing
that it does basically nothing. I want a bit more stereo sound.
thanks

(Karl Winkler) wrote in message . com...
(caveplayer) wrote in message . com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

You're getting two different mic techniques mixed up. XY is a
coincident technique (usually) involving two directional (such as
cardioid) mics crossed at (about) 90 degrees, with the two capsules
either right next to or right over one another. This way, wherever the
sounds originate, they arrive at both capsules simultaneously. Thus,
for your setup, you would simply place the pair of mics at 3 to 4 feet
away from your instrument. This seems a little close, however. I'd
suggest experimenting with this distance, depending on how good the
room or stage sounds.

The "3 to 1" rule is when using close single mics on several
instruments. The reason for this is to avoid phasing problems when
more than one mic picks up the same instrument. By having the intended
mic 3x closer to an instrument than the mics used for other
instruments, the bleed is far enough down that phasing problems are
minimized.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

Jeeez, i made a mistake, i meant to say spaced pair!
Well what you said makes sense. However, i was not enthralled with my
first experiment with X-Y, but i did it very close, like one foot
away.

The website Harmony central, which is a pretty good guitar website,
suggests using a spaced pair for one guitar. Is this a dumb thing to
do?

thanks.

"caveplayer" wrote in message
om...

Jeeez, i made a mistake, i meant to say spaced pair!
Well what you said makes sense. However, i was not enthralled with my
first experiment with X-Y, but i did it very close, like one foot
away.

The website Harmony central, which is a pretty good guitar website,
suggests using a spaced pair for one guitar. Is this a dumb thing to
do?

Not necessarily. I've used both XY and spaced pairs for single acoustic
guitars and gotten results that were good, but different. XY produces a
smallish sound, often good for mixing with other things. Spaced pair
typically produces a "larger-than-life" sound, at least when I do it and pan
hard L & R. Panned closer to the center (panpots at, say, 10 and 2 o'clock)
it can give a very nice effect.

Peace,
Paul

(caveplayer) wrote in message . com...
(Karl Winkler) wrote in message . com...
(caveplayer) wrote in message . com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

You're getting two different mic techniques mixed up. XY is a
coincident technique (usually) involving two directional (such as
cardioid) mics crossed at (about) 90 degrees, with the two capsules
either right next to or right over one another. This way, wherever the
sounds originate, they arrive at both capsules simultaneously. Thus,
for your setup, you would simply place the pair of mics at 3 to 4 feet
away from your instrument. This seems a little close, however. I'd
suggest experimenting with this distance, depending on how good the
room or stage sounds.

The "3 to 1" rule is when using close single mics on several
instruments. The reason for this is to avoid phasing problems when
more than one mic picks up the same instrument. By having the intended
mic 3x closer to an instrument than the mics used for other
instruments, the bleed is far enough down that phasing problems are
minimized.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

Jeeez, i made a mistake, i meant to say spaced pair!
Well what you said makes sense. However, i was not enthralled with my
first experiment with X-Y, but i did it very close, like one foot
away.

The website Harmony central, which is a pretty good guitar website,
suggests using a spaced pair for one guitar. Is this a dumb thing to
do?

thanks.

OK, I can see how you got that. However, a spaced pair is another
stereo technique (like XY) and again, the 3:1 rule is about close
miking with mono mics on an instrument each.

One "rule of thumb" I've seen (and tried) with spaced pair can also be
confused with the 3:1 rule. The idea is to place one of the mics in
your spaced pair 1/3 of the way from the left edge of your instrument
or ensemble, then the right mic 1/3 of the way in from the right edge
of the instrument or ensemble. Something like this:

---------------------------
| |
| instrument or group |
| |
---------------------------
--1/3---1/3-----1/3--
0--mics--0

The key here is to have them the "correct" distance from the
instrument/ensemble. I've found, however, that typically the mics have
to be closer together than that or else you get a "hole in the middle"
of the sound. Also, usually it is not realistic to have a classical
guitar that sounds as big as a house... I agree, though, that spaced
pair with real omnis is usually far better than XY, in terms of a
pleasing sound and a nice soundstage. *IF* it is done well.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

"Paul Stamler" wrote in message
...

Actually the classic XY or ORTF configurations using cardioid
microphones
angle them at 110 degrees. With hypercardioids you'd start at 90
degrees.
Vary either angle as needed (there's been another thread on that going
for a
couple of weeks now).


Define "classic." I use 110 degrees for ORTF (since that's what they
specified and it's a fundamental part of the design), but I use 90
degrees for X-Y.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)

"caveplayer" wrote:

Yes I know. that was just a typo. I realized just after i posted. I
meant to say spaced pair. I read about these basic setups from Harmony
Central, a guitar website. They do suggest, and even show a picture,
using spaced pair for a single guitar. I tried the X-Y and yes, it
does produce good mono. You can tell especially by panning and seeing
that it does basically nothing. I want a bit more stereo sound.
thanks

The MXL 603s has such a wide cardioid pattern that it's basically omni in
this application. I've had okay luck with a slightly narrower varient of
ORTF on solo guitar. I don't think it's that natural of a sound but using
those particular mics it's a lot wider stereo than XY.

-jw

"Lorin David Schultz" wrote in message
news:6ye9d.39445$223.14705@edtnps89...
"Paul Stamler" wrote in message
...

Actually the classic XY or ORTF configurations using cardioid
microphones
angle them at 110 degrees. With hypercardioids you'd start at 90
degrees.
Vary either angle as needed (there's been another thread on that going
for a
couple of weeks now).


Define "classic." I use 110 degrees for ORTF (since that's what they
specified and it's a fundamental part of the design), but I use 90
degrees for X-Y.

Classic (in this context): widely accepted over the years.

Peace,
Paul

The key here is to have them the "correct" distance from the
instrument/ensemble. I've found, however, that typically the mics have
to be closer together than that or else you get a "hole in the middle"
of the sound. Also, usually it is not realistic to have a classical
guitar that sounds as big as a house... I agree, though, that spaced
pair with real omnis is usually far better than XY, in terms of a
pleasing sound and a nice soundstage. *IF* it is done well.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

thanks,
i agree that the guitar shouldn't sound 'as big as a house'
Check out these pictures,
http://www.guitarists.net/lessons/vi...ic_guitar.html

The 'shoulder float' sounded good but with the shoulder mic pointing
down.
I really have not experimented much with ortf. If i do an ortf, should
the distance between the mics stay the same regardless of distance
from the instrument? Because I don't want to have the mics that close.

"caveplayer" wrote in message
om...

The 'shoulder float' sounded good but with the shoulder mic pointing
down.
I really have not experimented much with ortf. If i do an ortf, should
the distance between the mics stay the same regardless of distance
from the instrument? Because I don't want to have the mics that close.

Yes.

The main drawback of ORTF in this context is that it tends to exaggerate any
motion on the part of the player. If s/he moves an inch or two, the guitar
jumps around between speakers.

Peace,
Paul

'Cuse me, Karl, but when did you move from Neumann USA? Did I just go blank
and miss the announcement?

--


Roger W. Norman
SirMusic Studio

"Karl Winkler" wrote in message
om...
(caveplayer) wrote in message
. com...
I've heard the rule of thumb for x-y configuration is that the ratio
of distance between mics to distance from instrument should be about 3
to 1.
Is there any justification for this? So lets say, i'm using small cap
condensor mics (i have MXL 603S pair) and recording classical guitar.
I want a bit of the room sound so i have the mics about 3-4 feet from
the guitsr. So should they really be about 9-12 feet apart? And if so
where do i point them. (you can kick me off at any time, but i just
like the advice i get here much better than rec.classical.guitar)
thanks

You're getting two different mic techniques mixed up. XY is a
coincident technique (usually) involving two directional (such as
cardioid) mics crossed at (about) 90 degrees, with the two capsules
either right next to or right over one another. This way, wherever the
sounds originate, they arrive at both capsules simultaneously. Thus,
for your setup, you would simply place the pair of mics at 3 to 4 feet
away from your instrument. This seems a little close, however. I'd
suggest experimenting with this distance, depending on how good the
room or stage sounds.

The "3 to 1" rule is when using close single mics on several
instruments. The reason for this is to avoid phasing problems when
more than one mic picks up the same instrument. By having the intended
mic 3x closer to an instrument than the mics used for other
instruments, the bleed is far enough down that phasing problems are
minimized.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

The point being that one works within the area that sounds best on the
guitar, in this case. However, nobody really close mics an acoustic guitar
except in live situations so as to help alleviate bleed. 18" to 24" is
fine, but the diaphragms should be equidistant from the source, and defined
by a triangle to help deliniate the plane of the diaphragms.

But you can use headphones to help you move the mics during a setup if the
player isn't you, because you'll intimately hear the differences in mic
placement. So ultimately the choice comes down to you as where it sounds
best. All the math in the world doesn't describe good sound, but it does
describe a good starting place.

Also, in a spaced pair, don't feel that one should have to use the same mics
on both sides. It's not necessary, nor necessarily the best place to start.
One may use a small diaphragm condenser for the 12th fret position, whilst
using a U87 or any number of large diaphragm mics at the bridge position.
It's similar to overhead miking of drums in that neither mic is actually
going to be operating in exactly the same set of frequencies because of the
acoustics of the instrument. How you choose to view it will dictate how you
mic it. For instance, I may well decide that a couple of U87s are the
perfect thing for an acoustic guitar, but then I may not. I might use
totally different mics, regardless of their cost, or I may use a number of
mics over and above what a standard spaced pair would suggest. Some
acoustic guitars project extensively and I might want another mic some 6'
back (still follows the 3:1 rule at 24" for the spaced pair).

The point is not to get bogged down by the concept, but rather to use it as
a starting point to find the sound you want to represent for the instrument.

--


Roger W. Norman
SirMusic Studio

"caveplayer" wrote in message
om...
The key here is to have them the "correct" distance from the
instrument/ensemble. I've found, however, that typically the mics have
to be closer together than that or else you get a "hole in the middle"
of the sound. Also, usually it is not realistic to have a classical
guitar that sounds as big as a house... I agree, though, that spaced
pair with real omnis is usually far better than XY, in terms of a
pleasing sound and a nice soundstage. *IF* it is done well.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

thanks,
i agree that the guitar shouldn't sound 'as big as a house'
Check out these pictures,

http://www.guitarists.net/lessons/vi...ic_guitar.html

The 'shoulder float' sounded good but with the shoulder mic pointing
down.
I really have not experimented much with ortf. If i do an ortf, should
the distance between the mics stay the same regardless of distance
from the instrument? Because I don't want to have the mics that close.

"Roger W. Norman" wrote in message ...
'Cuse me, Karl, but when did you move from Neumann USA? Did I just go blank
and miss the announcement?


Roger, I started at Lectrosonics on August 16th, after taking a few
weeks off to "decompress" (compression isn't only bad for audio! g

Actually, though, I hadn't been directly involved in the Neumann/USA
operation for a couple of years. Instead, I had taken over marketing
communications for Sennheiser, and then at the beginning of this year,
taken over business management for all of the Sennheiser pro products
and markets. BUT it was time to step off that boat onto one with a
different culture, and moving at a different pace. Not only that, but
I've been an admirer of Lectrosonics for years... so it all worked out
OK and now I'm back in my home town of Albuquerque, NM, enjoying the
desert weather (no mold here!) and the incredible scenery. Can't
complain, although sometimes I still do (did I just rip that off from
Joe Walsh?)

If you're heading to AES, let's grab a beer or something. There may be
a few of us going out for a scotch after the show on the first day...

-Karl

"Roger W. Norman" wrote in message ...
The point being that one works within the area that sounds best on the
guitar, in this case. However, nobody really close mics an acoustic guitar
except in live situations so as to help alleviate bleed. 18" to 24" is
fine, but the diaphragms should be equidistant from the source, and defined
by a triangle to help deliniate the plane of the diaphragms.

But you can use headphones to help you move the mics during a setup if the
player isn't you, because you'll intimately hear the differences in mic
placement. So ultimately the choice comes down to you as where it sounds
best. All the math in the world doesn't describe good sound, but it does
describe a good starting place.

Hear Hear! g

Also, in a spaced pair, don't feel that one should have to use the same mics
on both sides. It's not necessary, nor necessarily the best place to start.
One may use a small diaphragm condenser for the 12th fret position, whilst
using a U87 or any number of large diaphragm mics at the bridge position.
It's similar to overhead miking of drums in that neither mic is actually
going to be operating in exactly the same set of frequencies because of the
acoustics of the instrument. How you choose to view it will dictate how you
mic it. For instance, I may well decide that a couple of U87s are the
perfect thing for an acoustic guitar, but then I may not. I might use
totally different mics, regardless of their cost, or I may use a number of
mics over and above what a standard spaced pair would suggest. Some
acoustic guitars project extensively and I might want another mic some 6'
back (still follows the 3:1 rule at 24" for the spaced pair).

I'd like to point out, however, that using two different mics may work
perfectly to get the sound you want, but it will not generate a
realistic soundstage. Spaced pair in general may not satisfy some
requirements for a "realistic soundstage" but by using two matched
mics (by that I mean the same type), and careful placement, it can
sound quite realistic in playback. Not the case for two dissimilar
mics. Not to say the result isn't stereo, because it is. But it's not
a stable soundstage IMO.

The point is not to get bogged down by the concept, but rather to use it as
a starting point to find the sound you want to represent for the instrument.

Agreed. No point in using any technique or approach unless it sounds
good, and sounds good to *you*.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com