Need simple answer for simple ???

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FullSailer

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Whats up everyone. I have a simple question When micing something "off axis" does that mean angling the mic or does that mean placing the mic straight forward off center of the speaker? Im assuming that it means angling the mic. If this is the case what is that used for? Anything will help. thanx

Eric
 
At first this question seems a little trivial...like most of us know that placing a mic "off axis" means that you're angling it away from the source...but then if you think about it....

Just what is this "axis"? Is it a line between the microphone and the source? But where on the source? An acoustic guitar emits all sorts of sound waves in all sorts of directions. A guitar cabinet might have 4 big speakers, where is the sound "originating from?"

It would seem to me that positioning a microphone "straight forward off center" and "angling" a microphone are very much the same concept...at least at first it seems that way...in either case you're changing the angle between the microphone and the source.

If you position a microphone such that it physically located near the edge of a speaker, but angled such that it's pointing at the center of a speaker, is that microphone "on axis" or "off axis"?

Slackmaster 2000
 
I mic an old fender band master. Two big speakers in the cabinet. Cabinet laid on its side. Mic pointed 90 degrees to the cabinet (directly at it), centered vertically, and exactly on the left edge of the right speaker. Sm57 about 4 inches from the cloth. Now since I have taken chalk and drawn an X right on that very spot.... am I micing on or off aX is?
 
kjam22 said:
I mic an old fender band master. Two big speakers in the cabinet. Cabinet laid on its side. Mic pointed 90 degrees to the cabinet (directly at it), centered vertically, and exactly on the left edge of the right speaker. Sm57 about 4 inches from the cloth. Now since I have taken chalk and drawn an X right on that very spot.... am I micing on or off aX is?
Click to expand...
If the front end of the SM-57 (where the grille is) is pointed directly towards the cabinet, the mic is on-axis. If you are pointing the mic at one edge of the speaker (i.e., not pointed directly at the center of the speaker, you are recording the speaker off-axis. The speaker and the microphone both have a central axis. With the center of the microphone pointed directly at the center of the speaker (with the mic placed directly in front of the center of the speaker), both the mic and the speaker are being used "on-axis".
 
"off axis" can be used to refer to the axis of directionality of the microphone itself, or to the axis of the sound of the instrument or amp. In the latter case, sometimes that is referred to as "off-line" to differentiate.

An example of the former would be singing into the side of a cardioid mic. An example of the latter would be placing a trumpet mic out of the direct line of the bell. You could have a "double off-axis", I suppose, by placing a cardioid mic off-line from a sound source, and then turning the mic so that it is pointing away from the source.

the real key is, position your microphones so that they get the sound you desire, and don't worry about the semantics.
 
It gets back to the point of near-field vs. far-field mic'ing of the instrument. If you're in the near-field, you're only getting a piece of the picture, anyways. At any given mic placement, you're getting an on-axis picture of where you're pointing it, and an off-axis picture of the areas you're not pointing it at.

In the far field, where the different radiation patterns are no longer as much of a consideration, then your're mic'ing the whole instrument, and the mic can be pointed at the instrument, or away from it.

In the end, experiment with your ears. Take a mic at a given placement, and point it in different directions with respect to the source. See how that colors the response differently. See, built in EQ! Far too few home rec'ers actually fully explore these options (myself included).

-mg
 
Straight in front of the capsule is 0° on a 360° polar axis - which in the brochure of the mic, generally denotes the mic's directionality at a given frequency. 90° is, of course precisely left or right of that 0° point. 180° is, directly opposite of 0°. When speaking of off-axidness, a corresponding number of degrees will always apply, although that number may or may not be mentioned. The term can be loosely applied to imply being outside of the primary pickup range of a directional mic, or to describe the position of a mic in relation to a given source, i.e., 'slightly off-axis'. The most important usage of the term "off-axis", however, is to denote that you are using the microphone outside the borders of a country which belongs to the "Axis Of Evil", which is quite an axis, indeed.

Brent Casey
Stu Dio Projects Microphones
877-563-6335


FullSailer said:
Whats up everyone. I have a simple question When micing something "off axis" does that mean angling the mic or does that mean placing the mic straight forward off center of the speaker? Im assuming that it means angling the mic. If this is the case what is that used for? Anything will help. thanx

Eric
Click to expand...
 
Interesting stuff...makes sense now...of course it's just a terminology thing, it's easier to communicate when everybody's speaking the same language :)

Slackmaster 2000
 
mgraffeo said:

In the end, experiment with your ears. Take a mic at a given placement, and point it in different directions with respect to the source. See how that colors the response differently. See, built in EQ! Far too few home rec'ers actually fully explore these options (myself included).

-mg
Click to expand...

Very good suggestions. Very true.

You know... I went through that process a few years back. I'd record my stuff with mic's set up in different places every time. After a couple of years... I decided on where I liked the sound the best. And being a person who is very much a creature of habit.... I have settled into a groove where everything is placed the same ... every time when I record my stuff. My line earlier about the guitar cabinet having an "X" on it wasn't a joke.

This gives me a standard to start with that I am familiar with. A sound that I can expect and anticipate. Then if I want to change the sound I do it on the board where I'm not wasting guitar licks or something. When I buy a new mic or something..... I spend about two days playing with it... recording with it... and then I almost write in stone how I want to place it. I'm pretty anal retentive that way.

But that's just the way I do it. It's quickest and easiest for me.... that doesn't make it correct.
 
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