Hello Steven. Welcome to the party.

I've got a whole lot of thoughts about your situation, but which point
is most important is hard to say since I don't know what your
recordings actually sound like now.

First of all, those SM81s are more than capable of recording some
huge-sounding acoustic guitar. The best acoustic guitar recording I've
ever done was with a pair of SM81s. Which is somewhat of a
coincidence, since I am able to make great recordings with a other
mikes as well. But you do not need a tube in there, and acoustic
guitar does not in any way benefit from using "big" microphones
(large-diaphragm condensers or any gimmicky junk with an oversized
body). The secret lies largely with technique, but before that I would
suggest a few other things:

Get rid of your DI channels. And did you say AMPS? If you want a
recording of an acoustic guitar that sounds "huger," you need to record
THE GUITAR and ONLY the guitar. You might think adding "more guitar"
tracks will give you a "bigger" sound, but it really does just the
opposite. If you take the time to listen extensively and closely,
you'll start to learn that FEWER microphones makes for a BIGGER sound.
A pickup will detract from the sound in the same way as another
microphone (due to slight timing differences which cause phase
cancellations). Besides that, there is not an acoustic guitar pickup
in the world that sounds like a REAL acoustic guitar. Stick with the
microphone(s). This is critical if you want a realistic, natural
guitar sound. This is true of all acoustic instruments, including
drums, cello, an entire orchestra, or whatever. I once had a client's
friend tell me, "But if the drums sound good with four microphones,
just imagine how much better they'll sound with like twelve!" To which
I replied, "If they sound good with four mikes, just imagine how much
better they'll sound with ONE!"

The mic preamp you choose can be an obstacle if it's real junk or if it
doesn't load the microphones properly, but it's a rather minor point
relative to a lot of other factors you should worry about first. The
most important is mic placement.

After that, you can still make the guitar sound "larger than life" by
using some gentle compression.

Also: The idea that tube gear (microphones, preamps, or compressors)
sound "bigger" or "warmer" than solid state gear is a myth. Tube
circuits that are implemented well are very clean. Crappy tube
circuits add distortion. Most tube circuits use transformers, which
are responsible for the "warmth" associated with tube gear, but there
are plenty of solid state preamps that use tubes also. But forget
about gear for a while. Let's talk about mic placement.

Okay, so I would say only use one microphone, except you want a stereo
recording, so no I'll say you should only use two microphones. For
acoustic guitar with a pair of cardioids, I think it makes the most
sense to arrange them in an "XY" coincident pattern. A narrowly spaced
pair (ORTF) could work too, but there are some reasons I'll get to
shortly why XY will probably be better for you.

In an XY arrangement, you put the capsules of the two microphones as
close together as you can get them, without causing excessive acoustic
interference between them. In a practical sense, this means that the
capsules will be almost touching, but arranged in a way such that
neither mic casts an acoustic "shadow" on the other. The effect is
that the two microphones pick up sound from effectively the same
location, so there are no timing differences between them. The stereo
image is due only to intensity differences caused by their directional
pickup patterns and the fact that they're angled 90 to 120 degrees
apart.

Okay, now you have the microphone "assembly" and you have to figure out
where to put it. This is where the whole "let your ears be the guide"
thing kicks in. Everybody has their own favorite spot. While one
person plays the guitar, another person needs to move around with one
finger in their ear until they find the "magic" spot. It will depend
on the room, the guitar, and the player. It might be straight out in
front of the player; it might be over their shoulder pointing downward;
it might be a bit to the left or right or high or low. You'll find out
for yourself.

But one important consideration is how far away from the guitar you
place the microphones. An acoustic guitar is a rather large, oddly
shaped resonator and it produces a variety of tones from various parts
of its whole. If you shove the mikes up against the sound hole, you
will not record the "whole" guitar. You'll get some thin trebly stuff
from the strings, and a bunch of boomy, woofy junk from the sound hole,
and you'll be missing a whole lot of "body." It's important to pull
back far enough from the instrument to capture its entirety.

Three issues arise with pulling away from the instrument. First of
all, directional microphones exhibit a tendency called "proximity
effect" which is a low-frequency boost on signals arriving from very
nearby. This is generally considered a good thing because it adds a
sense of body and richness that can enhance a recording. It can add a
"sense" of realism that makes up for the REAL sense of realism you lose
by virtue of not seeing the performance you're listening to a recording
of. Anyway, you pull away too far and you lose the proximity effect.
Secondly, when you pull the pair of microphones further away, your
stereo image of the guitar gets narrower because the "angular
separation" between one end of the guitar and the other appears
smaller, from the perspective of the microphone. Since there's not a
whole lot of stereo information there in the first place, you kind of
want to keep what you can.
Thirdly, as you pull away from the guitar, the ratio of direct sound to
reflected sound hitting the microphones will decrease. You'll hear the
room more; or as a greater portion of the overal sound. In a
bad-sounding room this is a bad thing. But if you're recording
acoustic guitar in a bad-sounding room, you're pretty well ****ed
anyway. In a good-sounding room, you'll love hearing the whole room
excited by the guitar and THIS is where that "bigness" (like a grand
piano, you said?) comes from. You'll get some new "stereo" information
because the room sound is being recorded in stereo. You will lose some
high-frequency crispness as the reflections add (and subtract) with the
direct sound, but it will sound realistic. In the right room, that
realism is a good thing.

Okay, so what will finally be the "correct" distance from the
microphones to the guitar? That's another thing I can't answer for
you. It depends mostly on the room, but also on the directionality of
the microphones, the tonality of the guitar, and of course your
personal tastes. In most cases anything less than a foot is going to
be too close, and anything more than about six feet will probably be
too much for you. If you started at two and a half feet, you could
then assess whether you're hearing too much room tone.

Okay, so let me reach back to my mention of spaced cardioids for a
minute. There's an "official" technique called ORTF which is a pair of
cardioids spaced something like 90 or 100cm apart, and angled slightly
away from one another. This was primarily used for orchestral work,
but you could use it to record acoustic guitar as well. The catch, in
my opinion, is that in order for it to be effective, it would have to
be placed much further away from the source than what we've been
discussing. Since the microphones are spaced, there will be phase
cancellations between them on any sounds arriving from the side. If
the microphones are too close to the guitar, overtones coming off the
far ends of the guitar will hit the microphones obliquely, and there
will be a very slight time delay between them, which can cause
realism-shattering phase discrepancies.

In summation, Steven, let me suggest that you save your money for a
while and in the meantime experiment much more with choice of venue and
microphone placement. A single pair of microphones in front of an
acoustic guitar into a digital recorder is a fairly portable situation,
so you should be able to take a few field trips to find out what some
local temple has to offer; or a friend's living room; or the locker
room down at the YMCA, or whatever. In the meantime, you can save up
your money so that if you DO end up buying another piece of gear to
help your recording process, you can take your time figuring out what
it ought to be, and hopefully have the budget to buy the best tool for
the job. Great River preamp.

ulysses

In article EFcvb.109$Yt4.31@lakeread05, Steven Dillon
wrote:

Hello,
First, I must say that this is my first post on this group. I have been
reading
your archives and sifting through searches for some help. It seems that
what I
am looking for is far too subjective for any one answer. Given that (and my
general lack of knowledge regarding microphones) I have decided to come
ask the experts for some opinions or maybe just some plain old guidance.

I am a solo acoustic fingerstyle guitarist and my story is that I want a
"bigger"
guitar sound for my next CD. For my debut CD I used two SM81's in X/Y.
It's a decent sound, but it's not big enough. So, I am considering adding
another mic to the mix.

I know Jon Best posts around these parts - Jon helped me put together my
home studio. Other folks where Jon used to work have told me over the
years that tube mics can make a guitar sound as big as a grand piano! For
me, that would be exactly what I am looking for.

Just for a bit more background information, I also mic my amps and use the
direct outs as input right to the board. So the tracks are composed from
all
of the inputs (unplugged and amplified).

What's the problem? Well, I need some help or guidance as to just where to
start. Your archives are full of, "let your ears decide", "there is no one
mic
that fits every solution or every guitar", "some mics when run through the
right
pre sound better than a tube mic", etc... The more I read, the more I
became
confused about where I should even be starting this journey... Here's a
couple
of questions that I fully understand may have about 100 answers that all
begin
with, "that depends".

Are there any non-tube mics that compare well (sound wise) to tube mics?

If I buy a tube mic, do you recommend using a pre-amp?

What exactly is the "right" pre-amp going to give me that I have yet to
capture using my SM81's by themselves and should I consider getting
a pre-amp for my SM81's?

About how much does a "good" pre-amp that would work with the SM81's
cost (keep in mind this is for a home studio on a budget)?

If I am only ever going to record acoustic guitar, can anyone recommend a
few large diaphram condensers mics that are generally real good for that
purpose?

Can I buy a "good" large diaphram condenser for less than $1000?

How about less than $600?

Am I even pointing in the right direction here - that is, am I looking in
the
wrong place for a bigger sound? Is adding another mic to the mix (one
that will surely give more depth to my sound) the right way to approach
the problem or is this just a matter of getting the mix right?

Sorry for the inane, neophyte questions you've seen 1000 times before,
but I think if someone can just help me eliminate choices, give me a
few good things to keep in mind, or a product line to investigate, I'll be
much better off than I am right now...

Thanks in advance for any help you can give.

Regards,

Steven Dillon

http://www.stevendillon.com
http://mp3.com/stevendillon