Multiple Microphones on Guitar Cabinets

Make sure (if you can at this point in the recording) that the sound fits with the other tracks. You will probably use a speaker that you wouldn’t like live for this process. A speaker with more mids than normal, like a Celestion Vintage 30, or maybe a Kendrick. Greenbacks are good live, but sometimes lose that all-important midrange on tape. Watch the speaker distortion! Get a power level that makes comfortable dynamics for you, maybe on the less compressed side so you gotta work just a wee bit harder than normal to crunch it up.

Initial Mic Placement

Now, stand in the room with the amp. Get your head moving around until you find the one speaker that sounds better than the others, or maybe just a real good spot where it seems to sound best. I am assuming we are not going after a “room” sound at this point. Stick a 57 right there, where your ear was.

Now, at the console, first verify that this is roughly the sound you heard out there. Be sure levels are where they should be etc… No EQ at this point on the console. Have someone move the mic back towards or away from the cab (or do it yourself with headphones). You are doing two things with this:

1) Changing the ratio of direct (from the speaker) vs. reflected (yeah you might be only a few inches from the cab but the room still is playing a huge part) sound coming into the mic.

2) Changing the amount of dynamic compression that the actual volume of the speaker is causing in the mic’s diaphragm, ribbon or voice coil. You are changing the behavior of the sound here.

Once you like the placement of your mic, its time to get very tricky.

The Second Mic: Dealing with Phase

One mic is almost never enough, but with two or more, phase cancellation rears its ugly head. Nevertheless, we got a trick for that right?

Here it comes.

Put the guitar down. Make it make noise, or take the cable off and stick it on something that will make noise. This noise has to be stable and constant…. a fender strat’s hum is perfect for this assuming it has some midrange harmonics to it.

Using your console’s meters, bring that noise up to wherever your “zero” is. This will probably require a lot of mic pre gain so make sure your speakers are turned down. Don’t let anyone touch the guitar or whatever the noise source is. Once you’ve got the signal to zero, mute the channel.

Next go into the room with the amp, and put your second mic about equidistant from the speaker as the first mic … Be careful not to disturb Mic#1.

Back in the control room, bring Mic#2 up to zero.

Now, very importantly, pull Mic#2’s fader (NOT mic pre) down to -infinity. Unmute Mic#1. Slowly push Mic#2’s fader up towards zero.

If the volume at your final Left Right Mix buss on your console goes up, you need to flip the phase of Mic#2. If your console doesn’t have a phase switch, make an out of phase cable. Just reverse pins 2 and 3 on an XLR, and make sure you label that cable so later on you don’t screw up some overheads or something. Remember: if the volume goes up, flip the phase.

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