whats the diff between XY and AB again?

[BobEddie]

i keep getting confused.

[jar4ever]

X/Y refers to a pair of mics with the capsules really close together and usually at a 90 degree angle from one another. It's a lot easier to see a drawing of it, but if you extend a line out from the capsule of the mic going forward it makes an X shape. X/Y's advantage is because the mics are so close together barely any phase or delay problems are possible, however you don't get as good as of a stereo image usually because time delay is a major part of stereo perception.

A/B usually referes to spaced pair, or at least that's how I've always heard it used. So basically a stereo pair where the mics are some distance apart and generally pointing in the same direction. This also for the possibilty of phase and time problems, but also gives a closer to normal stereo image (think about it, our ears are somewhat spaced apart).

[Blue Bear Sound]

(think about it, our ears are somewhat spaced apart).

Which is where ORTF comes in....

Similar to X/Y but the capsules are 17 cm apart and at a 110-degree angle (instead of 90 like XY)....

[jonnyc]

Anyone have any pics of ortf, I've always use xy or a spaced pair but never what you described blue, although I've heard the term a thousand times.

[Blue Bear Sound]

Various mic placement descriptions here --> http://www.nickspicks.com/faq-stereoplacement.htm

[MASSIVE Mastering]

ORTF overhead with 2 LDC's in use...

http://studio-central.com/phpbb/viewtopic.php?t=28878

[jar4ever]

Yeah, ORTF is pretty much supposed to simulate the distance and angles between the two ears, kind of a mix between spaced pair and x/y. It will give a better image then x/y but is more vulnerable to phase problems, especially in the high freqs.

[Blue Bear Sound]

Yeah, ORTF is pretty much supposed to simulate the distance and angles between the two ears, kind of a mix between spaced pair and x/y. It will give a better image then x/y but is more vulnerable to phase problems, especially in the high freqs.

It gives a wider image than XY and is much more cohesive than spaced pairs.... and it's not prone to phase problems any more than your ears are....

[jar4ever]

Well that may be true, you still want to minimalize cancelation and cone filtering as much as possible. And with ORTF the mics are far enough apart where it's quite possible hi frequencies could cause problems.

[Blue Bear Sound]

Well that may be true, you still want to minimalize cancelation and cone filtering as much as possible.

Ummm - there's no such thing as "cone filtering".... you probably meant "comb filtering"........

And with ORTF the mics are far enough apart where it's quite possible hi frequencies could cause problems.

There are no more phase issues with ORTF than you get with your own ears.... phase relationships are what gives you a sense of stereo imaging in the first place! What do you think gives you the spatial cues?

But hey - what do I know, I've only been doing this for more than a couple of decades....

[jar4ever]

Haha sorry, not trying to say you are wrong, and yeah I meant comb. What I'm saying is of course phase differences are a major part of stereo perception. However, since with ORTF there is a distance between the two mics and if one mic is slightly farther away from the source then the other one can get phase reversed and cause cancellation. This isn't just me saying this, all of my highly qualified teachers have said that with ORTF and spaced pair you have to watch out for unwanted cancellation.

[redheadbass]

This isn't just me saying this, all of my highly qualified teachers have said that with ORTF and spaced pair you have to watch out for unwanted cancellation.

Blue Bear is also a highly qualified teacher.

You will have phase issues of some sort anytime you have multiple mics on the same source.

Or multiple ears.

[jar4ever]

Yep, that's all I'm saying. Of couse, with x/y they are so close together that phase issues are only possible with very high frequencies.

[redheadbass]

Yep, that's all I'm saying. Of couse, with x/y they are so close together that phase issues are only possible with very high frequencies.

Remember that just because the fundamental tone is not that high, some sources, acoustic guitars being a good example, have very high overtones.

There's all sorts of phase summing and cancelling going on inside an acoustic guitar. That's why most of them are built roughly the same size and shape. It has a huge effect in producing their signature sound, as is the case with any hollow instrument.

BTW, I like using x/y placement on guitars, with different mics, usually a 57 and a condenser, sent to seperate tracks. It gives me more to tweak that way.

It works for me, but there are a lot of approaches I've seen.

I usually don't mess with tracking acoustic instruments on to a proper stereo track. Live ensemble playing can be another story, though

[MASSIVE Mastering]

Phase issues are part of basically *any* stereo recording. It's a compromise, just like anything else. You deal with a certain amount of it to make a mix sound the way you want and consult the mono button to make sure it isn't over-the-top (if you can't tell just by listening).

To that end, people tend to use what sounds most "natural" and proper to them at any particular stage - My own personal "rule of thumb" in most cases is to use ORTF for distant sources, and XY for closer sources (I almost can't imagine not using a vertical XY on an acoustic guitar).

It's not something to run from - It's something to be aware of.

[odyssic]

I've been using AB, but I think I might try the XY because I'm not getting very much bass. For one thing the acoustic I'm using is a Lowden O10 which doesn't have much bass response to begin with. Using AB I get mostly high end sounds. So I can't do AB with one mic closer to the body to up the bass because of phase issues. But I could place an xy setup very close to the body under the bridge for more of a bass response?

Thanks!

Steven