How to properly mic a guitar speaker?

[gutsofgold]

I understand that the sound from a speaker comes from the outer cone and not the inside section. And I also get the idea that the more off-axis your mic is, the less high end you capture.

Now...

Does off-axis assume the mic isn't pointing directly at the speaker, but rather at a 30-60* say?

Or does off-axis just refer to the fact that the mic isn't facing the center of the speaker?

And on a final note...why do so many guys take the mic, place it on the outer edge of the speaker, and then point it towards the center really sharp at like a 20* angle off of the speaker cloth? I'm just not catching the drift here.

[Phiz]

Does off-axis assume the mic isn't pointing directly at the speaker, but rather at a 30-60* say?

Or does off-axis just refer to the fact that the mic isn't facing the center of the speaker?

On-axis means the microphone is on, and aligned with, a line coming straight out of the center of the speaker. Any other positioning is considered off axis. Thus having the capsule on this center line, but not pointing the microphone at the center of the speaker would be an off-axis position. Having the microphone off this center line, but pointing at the center of the speaker is also off-axis.

As for the usage of extreme angles of microphone placement. This is often done as a way to EQ the signal a bit. Most non-omnidirectional microphones are most directional for high frequencies, and become more like an omni at low frequencies. Therefore, an extreme angle will roll off the highs a bit.

[drumsound]

I consider off-axis any angle of a mic compared to being pointed at the sound sources emanating waves.

So: On Axis

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Off Axis
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The red indicating the mic...sorry this is so crude

[Cryonicsound]

And on a final note...why do so many guys take the mic, place it on the outer edge of the speaker, and then point it towards the center really sharp at like a 20* angle off of the speaker cloth? I'm just not catching the drift here.

Because it sounds a certain way that they tend to find desirable. I'd recommend grabbing a guitarist friend and playing around with it to see what it's all about.

[Rolsen]

You know, you'll read it in every engineering book, tutorial, on-line reference, etc., but I don't know how anybody gets a usable sound from the outer edge of a speaker. Using different amps and typical dynamics, ribbons, or LDCs, miking the speaker edge always sounds like a fart through a bath towel to me. To sound anything like how I hear it, I must mic where the center dust cone meets the speaker and either push the mic closer, or pull back to taste regardless of mic.

[Vogon]

You know, you'll read it in every engineering book, tutorial, on-line reference, etc., but I don't know how anybody gets a usable sound from the outer edge of a speaker. Using different amps and typical dynamics, ribbons, or LDCs, miking the speaker edge always sounds like a fart through a bath towel to me..

I've used this position, but only in combination with another mic.
I sometimes use a centre mic and a side mic like this, mono them and tweak ditances to get intentional phase colouration.

[Professor]

First of all, it's really, really important to realize that there is no 'right way', 'best way', or 'proper way' to mic any instrument, including the noble electric guitar amp.

After all, if we step back for a moment and look at the situation doesn't it seem that there should be some difference between a single-driver cabinet and a twin?
...perhaps a difference between a twin and a 4x cabinet?
...perhaps a difference between 8-inch, 10-inch, and 12-inch drivers?
...between paper, poly, or aluminum drivers?
And just in case that ain't enough, we also have the mic to consider. Is it a dynamic? a condenser? a ribbon? is it a bright mic, a dark mic, or kinda neutral? is it slow or fast in its response? And how does that mic sound change when it is turned off-axis anyway?
Are you tracking in stereo to catch some room sound?
For that matter, consider the room... does it sound nice? Is the floor in front of the amp covered with carpet, or is it wood, cement, vinyl or some other material?

And if that ain't enough, it might be wise to consider the music?
Are you recording surf guitar or trash metal?
Is it a chunky background riff that needs to sound dark and thick while a soprano diva is delivering a seductive verse, or is a screaming solo that needs to make your ears bleed?

There's so many different possibilities, and hopefully as you learn about recording, you'll see that there is no such thing as a "proper" way to do just about anything.
Now that's not to say that there aren't techniques that work, or that every different combination of guitar/amp/room/player/style needs some special formula of mic/placement/etc. There are obviously plenty of guys who stick the same SM-57 in the same place infront of every amp for every kind of sound, and spend the rest of their time feeling they "got it right" while they are frantically dialing through compressors, equalizers, and countless other effects trying to blend the sound into the right spot in their mix.
My take on it, is the same as my take on every other instrument that might appear before you in the studio...
1st: learn your mics. That doesn't mean just knowing what they look like in catalogs, but it means using the mics that you own and learning how they sound in front of different instruments and in different places. Mics sound different off-axis, they tend to lose high frequencies, and might sound like a completely different mic at 90? off-center.
2nd: LISTEN!!! The guitar will tell you what it wants. It might sound bright and need to be tamed, or it might sound bright but not bright enough. It will have a sound and a tone that the player wants to have in the song, and you will want to capture that sound and make it fit into the overall soundscape you're creating. Some guys like to stick a finger in one ear and aim the other at the sound source and move around until it sounds good. If it sounds to your ear at dead center but 3-feet away, then put a mic there. If it sounds good two inches off the grill right at the edge of the driver, then put a mic there.
3rd: Put the two together. The guitar is asking for a particular sound, and your mics can deliver particular sounds, and when you hear what the amp needs and match it to what you know your mics can do, then you have found the perfect choice... for today.
4th: File that info away. It may never be the right sound again, but it might get you right where you want to be 90% of the time (if so, then you need to have your ears checked or change up musical styles once in a while). But it's your job as an "engineer" to work out those solutions and have a healthy stash of ideas-that-worked available for the next gig.

Oh yeah, and if you're really, really not sure whether one choice is better than all the others, then just put up a second mic and record another track. I'll assume you're not working on a limited medium like a 4-track or 8-track system. Personally I am always second-guessing my choices and testing new ideas against known results, so I'm almost always running 2, 3, maybe 4 mics on a single instrument, just to end up using one, or maybe a blend of two, on the final mix. That's also why I work on a system with a ridiculously high track count (192-tracks, with 64 input channels) so every session can teach me something new.

Ears take time to develop, and it can be frustrating along the way, but they only get better the more you use 'em.

-Jeremy

[gutsofgold]

wow thank you for that reply, how true.

[directaction]

A reamp box is a great tool for playing with mic positions on a guitar amp. Record a dry guitar signal through a D/I, and then reamp the signal on a loop. Play with your mic positions as needed.

[JWL]

Books have been written on this subject. My favorite is the mega-HTML explosion of Slipperman's recording distorted guitars. Google it, read it, learn it, live it.

[stevebozz]

I haven't had much luck getting a good guitar sound, especially distorted guitar, by placing a mic as close as possible to the speaker. If I have anything close to a 'it tends to work here' spot, it's about 1 - 3 feet away from the amp. Sometimes folks look at me strangely when I do this, but tend to like the end result.

I usually use 57's or ribbons, not much of a fan of condensers on loudspeakers. good luck!

[cgarges]

And I also get the idea that the more off-axis your mic is, the less high end you capture.

Not neccesarily. Putting the mic off-axis to the speaker movement introduces a phase error across the diaphragm of the mic. This often results in cancellation of some high frequencies, but can also make the sound coming out of the speaker somewhat peaky or shrill.

I usually start with the mic on-axis, in the spot that sounds good in front of the amp (which I determine by listening in front of the amp itself). Sometimes that's dead-center of the cone, sometimes it's not.

Chris Garges
Charlotte, NC

[MoreSpaceEcho]

I haven't had much luck getting a good guitar sound, especially distorted guitar, by placing a mic as close as possible to the speaker. If I have anything close to a 'it tends to work here' spot, it's about 1 - 3 feet away from the amp.

same here. almost never closer than 6". a 57 right up on the grille doesn't sound any kinda good to me AT ALL. yet somehow it seems other people make it work...the mysteries...

[drumsound]

I haven't had much luck getting a good guitar sound, especially distorted guitar, by placing a mic as close as possible to the speaker. If I have anything close to a 'it tends to work here' spot, it's about 1 - 3 feet away from the amp.

same here. almost never closer than 6". a 57 right up on the grille doesn't sound any kinda good to me AT ALL. yet somehow it seems other people make it work...the mysteries...

The reason I like the mic jammed up to the grill has to do with time feel. The player is reacting to the tempo they hear and playing accordingly. So I like keeping the mic close so that I'm not adding delay due to the sound traveling in space. To me 6" is pretty far and I don't often get much farther than that, unless it's an added room track or if the tone and delay are working for me in the tune.

I fine this feel thing is more important on overdub when the guitarist has the close snare mic in his ears, but even if they are getting a lot of Oh mics, they are still reacting to that as opposed to being in the room with the drum like on the basics. And even then often he might be watching the stick hit the drum and or how the drummer is moving.

If I were Andy Hong I'd probably have the math worked out so I could compensate for the position of the guitarist to the drum-set and track accordingly, but I'm nowhere near as smart as Andy! Just thinking about what the math might be like hurts my brain.

[sammyp]

You know, you'll read it in every engineering book, tutorial, on-line reference, etc., but I don't know how anybody gets a usable sound from the outer edge of a speaker. Using different amps and typical dynamics, ribbons, or LDCs, miking the speaker edge always sounds like a fart through a bath towel to me. To sound anything like how I hear it, I must mic where the center dust cone meets the speaker and either push the mic closer, or pull back to taste regardless of mic.

I totally agree, i've been a guitarist for 20 years and the outer part of the speaker has never sounded good for me during recording. It works sometimes on live pa gigs with teles but that's rare too.