Mic'ing amps with room mics

J

Jakob_v

New member
Hey, I've just recieved my LDC mic, and I want to use it as a room mic on my guitar amp. It's a 45watt mesa/boogie amp and I use a SM58 without windcap at the grille of the amp. We're talking about heavy guitars.

I've tried to move the mic around in front of the amp, from 1-5 feet, but it seems like everywhere I have the mic, I get either a boring sound, or bad phasing problems. I really don't think it's impossible to mic distorted guitars with room mics. James Hetfield, for example, recorded with up to 8 mics on "the Black Album"... not that the Black album tone is so great, it sounds overproduced, but there are no phasing problems there...

So, my question is, how do you guys handle phasing problems when using more than 1 mic? EQ for the bad sounds? Special mic placements? Special rooms?

I know many people like to use just one mic, but to me it sounds boring. I can already hear my recordings sound much more real, except the phasing problems.
 
Unless you have a good room, a room mic is not going to help! And... a large-diaphragm condensor isn't the best first choice for a room mic due to inherent off-axis response problems.

Have you tried listening just to the room-mic track? What does it sound like?
 
Yes, and I think the sounds will blend together very well if it's possible.

It DOES sound good when I combine them too, except the phasing problems of course.

Who have said I don't have a good room? :p
 
Jakob_v said:
So, my question is, how do you guys handle phasing problems when using more than 1 mic? EQ for the bad sounds? Special mic placements? Special rooms?
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If you have a bad phasing problem just move the mic inch by inch from where you want it to be. After you move it, record something, and if there is still a phasing problem just keep moving it until there is no phasing. So it's mostly the mic placement but it would help to have a good room.

And to be really confident there is no phasing, zoom in on the two guitar tracks until you can see the actual wave form of the audio and make sure they are matching up.
 
If you are recording digitally to a DAW, just grab the room mic track and drag it forward a tiny bit until it lines up with the close mic track. You'll have to zoom WAY in and find a large peak to line up visually. Single source, multiple mics, phase issues can be fix this way, multiple sources/multiple mics and you're SOL.
 
Jakob_v said:
Yes, and I think the sounds will blend together very well if it's possible.

It DOES sound good when I combine them too, except the phasing problems of course.

Who have said I don't have a good room? :p
Click to expand...

If you like the sound and it's just a phase problem... then the issue is simply mic placement. Just move the room mic around until you don't have a noticable phase problem. Alot of people seem to follow the 3-to-1 rule. Make the distance from the mics to the source a 3-to-1 ratio. So if your close mic is 1 foot away from the amp, make your room mic 3 foot away. Obviously you will probably just eyeball the distance rather then actually measuring (because you can hear if it's not right). Also, inches don't really matter when you are not close mic'ing... so don't be afraid to move the room mic 5 or 10 feet at a time in any direction until you find the sweet spot.

If you are trying to fix the phase issues in something you already recorded, you can drag the room mic track to sync up with the close mic track like Reshp1 mentioned.

BTW, if you don't have any decent acoustic treatment in your room... chances are you don't have a "good" room. ;) You should keep that in mind as you experiment with room mics because you'll get MUCH better results in a room with some good treatment. And no... egg crate foam is not a good room treatment. :D

Cheers!
 
I think the 3:1 rule deals with 2 sources and 2 mics. You want mic A 3 times as far from source B as source A, and mic B to be three times as far from source A as source B. When combined, source A is much weaker in the mic B signal as it is in the mic A signal so phasing is minimal, same goes for source B being weaker in the mic A channel than mic B channel.
 
Or you can flip the phase on one mic intentionally to start with. Move both mics untill they cancel each other out as much as possible. Flip the phase again and the mics should be in phase.
 
small reply

I tend to record amps at about 3-5 feet with two Pencil condenser mics using the three to one rule(mentioned by some one else ..Most amps have.nt got a real good sound up close anyway..

I also use a large studio mic about six feet back and six feet high

with all pad switchs on ...

If your room has had proper acoustic treatment and well balanced it would be hard to get bad sounds unless the mics are totally pieces of crap
 
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