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What is the best way to mic up an amp live and in the studio? I have heard people put the mic behind the cab in the back of the speakers if it is an open back.
 

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The "best" way is for you to get a few different mics and try different positions with different mics, then try combos. It'll take a few hours but you'll eventually find a sound that works for you. Before you begin, you should have an idea of what sound you want - whether its a tight driving sound, loose blues sound, old school "torn speak" sound, massive stacks metal sound. Something else? Try for something a little different from the norm.

For what its worth, I've dropped a single SM57 to side of the speaker of a small fender amp and run that through a tube preamp and got a pretty good sound for me. I've heard of running two different mics (an sm57 and a tough large diaphragm mic in front of the speaker and a PZM mic in the back of an open cabinet.

In the end, there's as many ways to mic a speaker as there are sound engineers.

Start with these positions, in front - close up center on speaker, to side of speaker (pointing at speaker), a foot in front the speaker, two feet in front, then in back, right inside the cabinet and then a foot back.

Another thing you can do, which works for any instrument, is cover one ear and move around till you "hear" a tone you like, then put a mic there.

Hope that helps.
 

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Just a side note:

If you mic both the front and back side of an open back cabinet, one of the mics will need to be phase inverted if both mics will be on at the same time, otherwise there will be some cancellation of the signal.

Some might say that micing the back side of the cabinet may get you out of phase with your 'off the stage' sound, but in reality every piece of gear in the PA or recording gear's signal path can alter the phasing by some degree.
 

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In the studio I like one mic up close and personal (just off axis and against the grill) and one back a few feet to capture the sound of the room.

Live, it's one mic and depending on the amp I sometimes point it directly at the dust cap and sometimes off axis, but always almost touching the grill.
 

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Just eyeballing those relative distances, I would think you'd have bad phasing problems. But maybe not.
If I match the levels that cancells at around 160Hz. I set up the parametric EQ to pull out 160 on one track when I mix the two together so they don't cancel.

The room is pretty live as well, there are lots of hard surfaces, but this setup is just to get basic guitar sounds into the computer.
 

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The 57 up close is where the bottom end is and the apex is just catching air, so I dont mind having to cut a few dB off the low end of it.

The main signal is actually direct out of the tubeworks preamp, the mics are added to taste when I mix things down. Both mics have phase issues with the direct signal, but it's not actually too bad.
 

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Looking at a picture and judging the sound is a bit difficult IMO.

I would start with something pretty close to what the OP's picture illustrates, but with the close mic closer and the far mic a bit farther. If a phasing or cancellation problem occurs it's generally pretty obvious and easy to correct.

But, all rooms having their own sonic characteristics and the same being true for amps and guitars, one does have to use one's ears to judge how a particular mic'ing arrangement works.
 

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Hey Guys,

The set up pictured is just a quick and dirty set up to grab guitar samples for a web site. The room is very hard and very live and it has lots of natural reverb which actually sounds nice, not harsh. The mics are used to add some openness and get this natural rev onto the tracks to make things sound less focused than the direct line out. With that said, the two mics on their own in this configuration sound fine and the whole thing is workable.

The entire situation is not 'ideal' for recording, but I do live sound and I am used to working in less than ideal conditions. Combing filters are easy to hear and easy to treat with a single source and multiple lines using the EQ on the individual tracks. Also the end result is more than satisfactory for its intended purpose.

The mics have been sitting there unused for over a month so, they have moved and the cabinet that they are micing likely has as well. The grill is normally off the cabinet when recording as it rattles a bit every now and then.

If I ever get my player back, these clips will be on my website, so you will be able to hear what this setup sounds like.

I would record the tracks myself, but I am not that versatile of a player and more than a little on the unbridled side.
 

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Guys,

I didn't mean to open up a can of worms here...

The two mics are about 40 inches apart, they will comb primarily at the frequency with twice that in wavelength (~160Hz). The distant mic does not benift from the proximity effect, so the lower end range isn't all that important, and it can be EQ'ed out to nullify its effect on the close mic. Any phasing as higher wave lengths is hardly noticable, if at all.

The room is live, and is kicking back lots of relections which is where I am getting my rev from. The direct sound of the pre amp is bone dry, and very focused.

All the technical aspects aside, this is quick and dirty. Two mics on one stand and a direct line out. I bring them up on seperate tracks, each one individually gives me what I'm after, there is a slight combing problem with the distant mic which is easily rectified. In the end, I get the result I'm after so I don't see any problem with it. With that being said, there is no need to move the mics or treat the room in any way.

I've heard lots of stuff that comes out of perfectly engineered studios, with ideal environments that sound like total crap. I've also heard bands play in hockey arenas and the sound was fantastic.

EQs are not evil, I've made a living by knowing how to use one. Look at relative mic placements in live situations, no where near ideal and the loudest ones move around. The main front of house graphs are for EQing the room and the environment in relation to the mics. Other than a few basic guide-lines, the whole technical aspect doesn't really matter if what you are hearing sounds good. Mixing audio is not a technical skill and it does not require any at all. If something sounds wishy-washy it doesn't really matter why, it only matters that you recognize it as a problem and can deal with it. Mix with your ears, not with your eyes or by some rulebook.

I'm not knocking the importance of proper mic placement, accostically nuetral rooms, or anyone else's opinion for that matter. I'm just pointing out that they are not the be all end all when it comes to shoving a couple of mics in front of a guitar cabinet and getting a sound that works for me.

I think GuitarPix said it best way back in the second post of this thread:

"In the end, there's as many ways to mic a speaker as there are sound engineers."
 

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The quick & dirty

Here is what that quick & dirty set up sounds like without the direct signal.

The left side is the 57 and the right side is the room with a both mics totally flat.

After it is converted to a 128K mp3, the bottom end has lost all of its punch and there is some top end digital trash in it. The over all dynamics are also pretty much gone to hell and it sounds pathetically life-less, but as I said this is just quick and dirty to get a few sound clips on a web site, and I'll spend some time polishing up the end product.

Adding in the focused direct signal in the center gives me what I am after, considering that most people will be listening to these tracks through plastic computer speakers, this is by no means a professional production.

This is just me messing around setting levels with an FGS, I am going to get a guy that can actually play record the tracks for the web site for me. So, the end product will have the center channel and a guy that can play, which will make a big difference. I'll also put some time into getting it to sound right when it is converted to MP3 and the actual mixing of the tracks - this is just two raw tracks panned left and right.

So with total disregard for mic placement, room treatment and musical talent, this is what you end up with:

http://www.hammguitars.com/guitarscanada/mp3/FGS1.mp3
 
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