Digging around the web for advice about recording electric guitars, I
came across

http://www.homerecordingconnection.c...ry&id=140#q131

The author suggests using two mics on a single cabinet (one further
back than the other) and spending a lot of effort to tune the relative
placements of the mics to get them "in phase." Does that make any
sense? As I posted on that page,

"Unless I'm missing something, it's only possible to get two mics to
be "in phase" w.r.t. particular frequencies. Getting the mics to
hear the signal in phase depends on the spacing between them a
multiple of the wavelength of the sound. If they're off by half a
wavelength, they'll be perfectly out-of-phase. Since different
frequencies correspond to different wavelengths, it seems to me you
can never get them in phase for all the notes a guitar will
play."

So, what *am* I missing?

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

David Abrahams wrote:

The author suggests using two mics on a single cabinet (one further
back than the other) and spending a lot of effort to tune the relative
placements of the mics to get them "in phase." Does that make any
sense?

Technically, they'll only be in phase at one frequency (and its
harmonics). What it really means is that you adjust the position of the
mics so that it sounds better when you combine them than when you use
just one or the other. This sometimes is a function of certain
frequencies or reflections being out of phase and partially cancelling
so they don't detract from the sound you're trying to achieve.

The idea of a distant mic is to get the sound of the amplifier in the
room. If that sounds good, you can use it in your mix. If it sounds
bad, then it's better not to use it at all. You just have to listen.

"Mike Rivers" writes:

David Abrahams wrote:

The author suggests using two mics on a single cabinet (one further
back than the other) and spending a lot of effort to tune the relative
placements of the mics to get them "in phase." Does that make any
sense?

Technically, they'll only be in phase at one frequency (and its
harmonics).

That's what I thought.

What it really means is that you adjust the position of the
mics so that it sounds better when you combine them than when you use
just one or the other. This sometimes is a function of certain
frequencies or reflections being out of phase and partially cancelling
so they don't detract from the sound you're trying to achieve.

To me they seemed to sound a lot better together no matter how far
apart they were.

The idea of a distant mic is to get the sound of the amplifier in
the room. If that sounds good, you can use it in your mix. If it
sounds bad, then it's better not to use it at all. You just have to
listen.

Well, that's not why the author of the article uses two mics, and the
2nd one isn't really distant (see the picture at
http://www.homerecordingconnection.c...w_story&id=140).
He's doing it to capture all the tonal qualities present in the guitar
sound:

There are two fields of thought on Mic usage when mic'ing guitar
cabinets / amps. Using a Dynamic mic like a Sure SM-57 gives a very
"gritty" sound, but often lacks top end sparkle that makes the sound
cut through in a mix meaning you have to apply lots of EQ and / or
reverb to get a usable sound. Using a Condenser mic will often give
a more detailed sound with more "fizz", but often lacks
lower-frequency response and as a result can sound too "thin" and
"transparent".

Interestingly, in my session it seemed to be the condenser that
provided the missing lows.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

On Thu, 08 Jun 2006 06:33:40 -0400, David Abrahams
wrote:

The author suggests using two mics on a single cabinet (one further
back than the other) and spending a lot of effort to tune the relative
placements of the mics to get them "in phase." Does that make any
sense? As I posted on that page,

"Unless I'm missing something, it's only possible to get two mics to
be "in phase" w.r.t. particular frequencies. Getting the mics to
hear the signal in phase depends on the spacing between them a
multiple of the wavelength of the sound. If they're off by half a
wavelength, they'll be perfectly out-of-phase. Since different
frequencies correspond to different wavelengths, it seems to me you
can never get them in phase for all the notes a guitar will
play."

So, what *am* I missing?


You can use a close mic and a distant mic on a guitar cabinet. They
will sound different. When you mix them together, particularly if you
boost the gain of the distant mic to equalise its volume to the close
mic, you may get phase effects at certain frequencies. You may like
these effects, you may not. Play with the mic positioning, relative
levels and stereo panning (but check mono compatibility, if relevant).

David Abrahams wrote:
Digging around the web for advice about recording electric guitars, I
came across

http://www.homerecordingconnection.c...ry&id=140#q131

The author suggests using two mics on a single cabinet (one further
back than the other) and spending a lot of effort to tune the relative
placements of the mics to get them "in phase." Does that make any
sense? As I posted on that page,

"Unless I'm missing something, it's only possible to get two mics to
be "in phase" w.r.t. particular frequencies. Getting the mics to
hear the signal in phase depends on the spacing between them a
multiple of the wavelength of the sound. If they're off by half a
wavelength, they'll be perfectly out-of-phase. Since different
frequencies correspond to different wavelengths, it seems to me you
can never get them in phase for all the notes a guitar will
play."

So, what *am* I missing?

The whole POINT of setting up two mikes on the cabinet is that you get
comb filtering when the two are combined. By moving the mikes around,
you change the relative phase betwene them and you therefore move around
the poles and zeros of the comb filter and change the frequency response.

So, there is some frequencies where they are in phase and some where
they cancel out.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

.... and things get worse when you use distortion on your guitar....

David Abrahams wrote:

To me they seemed to sound a lot better together no matter how far
apart they were.

That's not unreasonable. The distant mic (if the room is live at all)
will have so much stuff in it that's going to be partially out of phase
with the close mic, and very little that's phase-coherent (or
phase-opposite) so you'll only get a little cancellation, and a lot of
room ambience, which in general makes a recorded instrument amplifier
sound better.

Well, that's not why the author of the article uses two mics, and the
2nd one isn't really distant (see the picture at
http://www.homerecordingconnection.c...w_story&id=140).
He's doing it to capture all the tonal qualities present in the guitar
sound:

That's another approach. Same with acoustic guitars, violins, irish
bagpipes, you name it. You get different sounds coming off the
instrument in different directions (even roughly the same direction but
coming from different areas of the speaker cone as this article
suggests from the photo) and it's OK to try to combine those for a
pleasing effect. The idea of using a distant mic is that when you get
far enough away, all of those sounds are going to blend in the room and
that's what the distant mic will hear as the "guitar" sound. It's kind
of like what you hear when you're a sensible distance from the
amplifier.

But if you want to close-mic everything and you want to get those
sounds that miss one mic, you have to up another one. And since there
will be about the same amount of direct, and hence phase-coherent
energy in each of the two mics, you need to play around with their
distance to be sure you don't cancel anything important. I'm not sure I
get the "gritty" part, but perhaps that's what's emphasized when you
put an SM-58 fairly close to the center of the cone.

Interestingly, in my session it seemed to be the condenser that
provided the missing lows.

I'm not surprised. Putting two different kinds of mic at roughly the
same position is kind of a gimmick. It might be effective, but chances
are you can find one mic that will capture the full sound nicely, and
adding the second mic gives you something that you don't hear live. But
if that's what sounds good, no reason not to do it.

I've never worked with a guitar player who is fussy enough not to like
the sound of a reasonably good mic a couple of feet away from his
amplifier - as long as his amplifier sounds good.

David Abrahams wrote in
:


Digging around the web for advice about recording electric
guitars, I came across

http://www.homerecordingconnection.com/news.php?
action=view_s
tory&id=140#q131

The author suggests using two mics on a single cabinet (one
further back than the other) and spending a lot of effort to
tune the relative placements of the mics to get them "in
phase." Does that make any sense? As I posted on that page,

"Unless I'm missing something, it's only possible to get two
mics to be "in phase" w.r.t. particular frequencies. Getting
the mics to hear the signal in phase depends on the spacing
between them a multiple of the wavelength of the sound. If
they're off by half a wavelength, they'll be perfectly
out-of-phase. Since different frequencies correspond to
different wavelengths, it seems to me you can never get them
in phase for all the notes a guitar will play."

So, what *am* I missing?


easy money and great sex, like everybody else, but consider that
a 1KHz signal has a 1.05 foot wavelength. so that spacing is
critical with 6 inches putting you out of phase. at 100 Hz
moving the mic that 6 inches will shift the phase about 20
degrees, which has minimal impact. Since music is distinct
frequencies, you can find phase relationships that seem to work
well for getting most of the notes in phase, and the out of
phase frequencies occur "between the notes".

--
Bob Quintal

PA is y I've altered my email address.

--
Posted via a free Usenet account from http://www.teranews.com

In article ,
"Federico" wrote:

... and things get worse when you use distortion on your guitar....

or better, depending on your point of view.

Edwin

"Mike Rivers" writes:

I've never worked with a guitar player who is fussy enough not to like
the sound of a reasonably good mic a couple of feet away from his
amplifier - as long as his amplifier sounds good.

That's where my condenser is sitting, but the sm58 near the speaker
cone is definitely adding some missing brightness. And yes, my AC30
sounds *really* good

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

David Abrahams wrote:
"Mike Rivers" writes:

I've never worked with a guitar player who is fussy enough not to like
the sound of a reasonably good mic a couple of feet away from his
amplifier - as long as his amplifier sounds good.

That's where my condenser is sitting, but the sm58 near the speaker
cone is definitely adding some missing brightness. And yes, my AC30
sounds *really* good

An SM-58 is adding brightness? There's something goofy going on there
(possibly that it's actually removing something else).

If you want brighter, move to the center of the cone. If you want less
bright, move to the edge.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."