Micing Open Back Cabinet ?

[arcaxis]

Most information I see about micing amps, is simply throw an SM-57 in front of the speaker and wail away. Guess I'm wondering if there's any value of micing the front as well as capturing some ambient sound from the rear of an open back cabinet. Just thinking this would be more realistic to what the ear actually hears.

[Major Tom]

I'm not sure, but seems like in theory, at least, the 2 mics would be complely out of phase, so when they were mixed together they would cancel each other out. I guess you could reverse the phase on one of the mics though... I think the standard method to get more ambience or "air" is to put one mic right up on the grill, and place another a couple or few feet back, still facing the front of the amp, or use a PZM for the 2nd....

[kid klash]

Originally posted by arcaxis
Most information I see about micing amps, is simply throw an SM-57 in front of the speaker and wail away. Guess I'm wondering if there's any value of micing the front as well as capturing some ambient sound from the rear of an open back cabinet. Just thinking this would be more realistic to what the ear actually hears.

It's pretty standard to close-mic the front of an open-back combo, and mic the back too (with the polarity flipped at the rear mic's preamp). You'll get the "in your face" sound from the front, and the "warm and wide" sound from the back. As long as the rear mic has the polarity flipped 180 degrees, you'll have minimal phase cancelation.

[Richard Monroe]

Agree with Kid Klash. I have found it effective to mic the back of the cab with a kick drum mic, as it kicks out so much bass back there. And as far as that backed off ambience mic goes, I have to say-not in my room, maybe yours.-Richie

[donkeystyle]

kid clash and richard monroe.......... wise words that i agree with

[arcaxis]

Thanks guys,
I had played around with close and far micing on the backside a little and it didn't do what I expected. I overlooked the phasing issue, so I guess this weekend I'm going to play around with this a little more.

[Phosphene]

Can you capture more bass by taking the back off of a say, Mesa 412 and micing front & back OR would that decrease the bass response from the front by having the back off?

[Dethska]

I would think that would cause less bass. A closed cabinet is almost always a lot bassier than an open back. you could still stick a mic back there.

[Richard Monroe]

Don't pull the back off a closed cab. It's not tuned to work that way, and there isn't much point in mic'ing the back. Closed cabs don't really put out more bass, just more punch (more moving air).-Richie