Thread: Mic Questions
View Single Post
  #13   Report Post  
Steven Dillon
 
Posts: n/a
Default Mic Questions

Ulysses,
Thanks man! This is some of the best information I have seen anywhere
on recording acoustic guitar! This one is going in my archive!! See my
comments and further questions interspersed below...

"Justin Ulysses Morse" wrote in message
m...
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,

Yikes.... That hurts to hear... I'm afraid I'm stuck with needing
my amps... :-( There are certain techniques that I use that I don't
believe a microphone can pick up. Not many, mind you, but a few.
And enough to where I'll need an input to the board from an amp
to hear it. Perhaps this is just a matter of shaping the mix afterwards.
Make the sound big without the amp on the parts where adding the
amp will take away from the sound, and then put the amp in where
the opposite is true... Does that make sense?

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

So true, so true... Now, with that point agreed upon, I'll say that
I'm not necessarily after the "true" acoustic sound. It's a tad more
raw than that... More like Preston Reed's sound... It's got balls
that an unplugged acoustic guitar just doesn't have.

microphone(s). This is critical if you want a realistic, natural
guitar sound. This is true of all acoustic instruments, including

Right, so what rules can we bend or how does the playing field
change if we allow for a sound that is sort of real but still has
elements of being amplified?

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!"

I can try taking some of the inputs away and see if I can get the
sound to be bigger. I had not thought of that until reading this!

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.

I don't think my compressor is good enough to make a difference.
It's an el'cheapo Alesis that came with my studio in box... But,
that is something that I could have a real studio apply during the
mix down, yes?

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.

Excellent information - should be in a FAQ someplace if it isn't
already!

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.

There is a golden rule that audiophiles apply to mixing and matching
components in high end stereo systems - the pieces have to match in
quality or the higher piece will point out weaknesses in a lower piece.
For example, running a boom box into $25,000 speakers shows
that the output from the boom box stinks... You basically have to
try to find equivalent gear (spec wise) and pair them together
for the best sound. Does that rule apply to recording too? In other
words, if I was to put my money towards a Great River and keep my
Alesis studio in a box (using an Alesis XT-20 ADAT), is the pre-amp
going to be so good that it will expose system wide weaknesses?

Thanks for everything, you have been very helpful...

Regards,

Steven Dillon

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