Double Micing Guitar Amps & Phasing

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Loxley

New member
So, I have just started tracking my music on my own for the first time in a (semi)professional manner. I'm recording into Pro Tools 10 with drum machines and synthesizers (that's the easy part). Now I'm recording electric guitar tracks, but I'm feeling a bit unsure of myself and could probably use some sage advice before I get too deep.

Basically, I'm trying to get a wide range of sound with a couple of mics, likely layering multiple guitar parts. I'm using an SM57 on the amp, usually just over the edge of the dust cap on the speaker. I'm also playing around with a CAD M177 condenser roughly 5-8 feet in front, level with the amp.

Here's my concern: I know what direct, 180 degree phasing looks and sounds like - an opposite wave of the other one. However, how do I tell if there's "gray" phasing where it's not 100% clear, but it might be there. Someone please alleviate my fears and tell me how to identify this and work around it. Thanks!
 
It will sound thinner with both mics than it does with either mic by itself, if you have a phase issue.

The only way to not have the mics out of phase is to have them exactly the same distance from the speaker.

The way to keep.phase from having an impact on the sound is to have [never of the mics at least 9db quieter than the other.
 
If the source is mono, don't use 2 mics, it can work well on acoustic guitars but not so much electric from experience, even on acoustic though I often prefer one well placed mic over 2.
 
Loxley said:
Here's my concern: I know what direct, 180 degree phasing looks and sounds like - an opposite wave of the other one. However, how do I tell if there's "gray" phasing where it's not 100% clear, but it might be there. Someone please alleviate my fears and tell me how to identify this and work around it. Thanks!
Click to expand...


Just use your ears...as cliché as that may sound.

I wouldn't waste my time looking at the waves of the two tracks or some phase meter plugin....just bring up the levels of each track until the blend sounds good.
You can center-pan both tracks, get their levels balanced to where the combination sounds good to you...then pan them where you want and leave the levels alone, or group-adjust their levels as needed to fit the rest of the mix.

Phase difference is part of recording and hearing.

Otherwise, just use one mic and avoid any of that.
 
Agree with Miroslavs advise. I typically record the cabinet with an SM57, and then use an LDC most often a C414, sometimes as much as 20' away to capture the room and make the instrument sound wider. What are you to trying to achieve, a "bigger" guitar sound? Don't worry about phase in this instance. On playback I generally will take each channel separately and use the phase button on my daw to see if one (or both) channels sound better out of phase.
 
It's important to remember that nobody who hears your music will have heard the original amp in the original room - if it sounds good to you in the mix then it probably is.

Phase alignment is always gonna be an issue with multiple mics, but you don't have to always use all of them, and sometimes it adds as much as it takes away.
 
Exactly. Trying to capture the exact sound of the amp in the room is pointless. I always had the amp in the control room and the cab in another room so I could tweak the sound a cording to what the mics were picking up, not what I was feeling in the room.

I always double mice cabs. I used a 57 and a 421 at the same distance from the speaker. Those two mics compliment each other very well.
 
a classic example of a BIG room sound, and a direct miced cab,
is the fine song by Robin Trower, "Bridge of sighs"

https://www.youtube.com/watch?v=PVBdnY3WgPY


if you listen to the beginning,
you hear the room mics only,
then slowly the engineer brings up the close mic, and the guitar becomes front and center,
but that nice big room sound is still there.

if you can listen in the cans,
you might be able to tell if the mix favors the room mic to one side or the other.

on my own recordings,
i have experimented with almost all possibilites.....

i've found that if my room mic is in a straight line back from where my close mic is,
that seems to eliminate SOME of the phase issues....
but if you hard pan the room mic to one side,
and even make a copy of it and hard pan to the other side,
bring it down in the mix,
and center your dry close mic track,
that's about as big as you can get it.



but the simplest method,
as the other guys have described,
is just to close mic,
and add 'room' in as an FX, that you can control without worry of phase.

i still like the old school method, tho,
especially if i'm on location and find a really good sounding room,
i'll ALWAYS place a room mic, and decide later whether to use it or not.
 
found THIS in SOS:

Adding Ambient Mics

"I've always thought that most people mic amps too closely," comments Alan Parsons. "They supposedly make up with an ambient mic, but I much prefer to find a mic position that works and process that, rather than mix in too much ambience." Despite Parsons' disapproval, though, a lot of the engineers I researched divulged that they use additional ambient mics to capture more of the sound of the room in which the guitar cab was recorded.

For example, Al Schmitt starts with the traditional SM57 close mic, on axis but a little off the centre of the cone. "Then I'll put a really good mic up — maybe a Neumann U67 or an M50 — for the room... It could be anywhere from 15 to 20 feet away." It's worth noting that the M50 is an omni microphone and, although the omni polar pattern is only very occasionally mentioned for close-miking, it makes a much more sensible choice for capturing natural room ambience.
Tony Visconti is also into using ambient mics: "I'm very much a fan of the room sound, too. I always record it if it's a real heavy rock guitar with power chords and crunches and all. I'll go around the room and clap my hands and I say, 'Put the mics there, that's it.' Quite often, I'll turn the room mic towards the studio window, and you'll get a reflection of the guitar sound — not directly facing it, because you're looking for reflections." Although he states in the same interview that he'll try to use a pair of U87s for ambience if possible, he's also mentioned elsewhere using PZM mics as an alternative.
Perhaps the most dramatic of ambient mic techniques, though, comes courtesy of Chris Tsangarides. His 'Vortex' involves using studio screens to build 30-foot-long walls along each side of the guitar cabinet, creating a flare shape (apparently inspired by the shape of a bass bin). Within this flare, he places a close condenser mic and typically another couple of condenser mics with different distant positionings, perhaps at 15 and 30 feet away. "I walk around while the guy's playing and find a sweet spot and put the mic there", says Chris.
By panning the distant mics to the opposite side of the mix from the close mic, you can create interesting panning effects for solos. "If it's a rhythm part, you get this huge sound because the whole thing is spread across the stereo spectrum." When double-tracking lead or rhythm parts, a useful trick is to reverse the panning of the direct and distant mics. "If there were two guitarists in a band, I would record them like that, so you got a wall of sound that had a transparency that would allow the drums and bass to come through."
While experimenting with the Vortex for this article, I was impressed by quite how well the ambient mics seemed to turn a close-miked guitar sound into something that sounded like it was on a record, but the downside of this approach for most home recordists will be that the Vortex is not easy to recreate in a smaller studio — so I thought I'd pass on some ways I found to make it more manageable on a smaller scale. One problem most small studios have is that they don't have large numbers of screens, but in practice I found that I was able to get decent results by putting the guitar cab in the corner of the room and using one or both of the room boundaries in place of the screens. Visconti's trick of aiming ambient mics at the studio glass also turned out to be handy to increase the apparent distance of the farther ambient mic.
 
another technique worth trying is Mid/Side, I've had great results with this in the past, you can easily blend in the ambient (side) mic...the side must be a fig 8 mic though.
 
If I want a phase coherent pair of tracks (which isn't automatically the case) I just slide the far mic track to the left until it compensates for the time/distance difference between it and the close mic track.
 
I love close miking cabs, I like distance miking the room, but intermediate mics combined with a close mic never pleases my ear. Like say you have one on the grill, fine, and one 2-4 feet away, also fine. What's not fine is combining them. That intermediate 2-4 foot distance throws the whole thing off to me. Get one mic way far away, like 8 ft or more, or put it right up on the grill with the other. That's best to me. And don't make that room mic way loud. Just use it for flavor.
 
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