Question about XY mic'ing

[Matt Grondin]

Ok, so what's the fundamental difference between doing XY mic'ing the way it's shown in the first picture as opposed to the second. Method one seems to be the popular way to setup small diaphragm condensers for XY, and method two seems the preferred choice for LDC's... does it essentially achive the same result? Also, is the 3:1 rule for spaced pairs at all relevant for doing drum overheads? It seems virtually impossible to have the mics between 3 times as far away from each as they are from the drums. Thanks.

Here's the first XY pic and the second will be in the next post.

[Matt Grondin]

Here's the second style... are they the exact same thing and my brain is just confusing me because one's a SDC and the other's a LDC setup. Stereo mic'ing is kind of confusing sometimes... are they any good primers on the subject? Thanks.

[Matt Grondin]

Also, I'm wicked confused about how the panning would work in XY mic'ing.... trying an experiment on piano recently made me confused... I'll do my best to explain.

I started by putting a pair of m930's just like in the photo on the hammers... I had the mic closest to the player aimed towards the bass and vice versa for the other mic... I panned them as if I was looking at them, having the one on the bass notes panned left and the one aimed at the treble notes panned right... essentially, I had the piano panned as if you were playing it, with it panning left to right from lowest notes to highest notes... makes sense, right? I like to pan drums the same way, as if you're sitting there playing them.

So when I put some mics out front outside the lid, my panning would be opposite I'm assuming... the mic aimed at the treble strings would be panned left and the mic aimed towards the bass strings would be panned right... now, maybe I'm overanalyzing things, but wouldn't have two sets of mics, panned completely opposite, on the same source, cause phase issues? Should I have the one facing left be my first input and the one facing right be my second input regardless of where the mics are located and being aimed, or does it not matter? I guess the same goes for stereo drum rooms mics being panned the opposite of your overheads... what's the right way to do it? I think I must be overanalyzing this shit, but I'm so confused. Thanks

[Andreas G]

XY is about the position of the mics membrane, not the housings. You always have to figure out, how the membrane sits in the housing.

Andreas

[5down1up]

first picture is a lil confusing !!!

imho it doesnt show XY setup ... its just 2 mics ! maybe you mean the right thing but the pic doesnt look like at all !

heres a better view of how to set up XY :

http://images.google.de/imgres?imgur...WE:de%26sa%3DN

pic no 2 looks as a microphone technique called MS ( mid side ) .
one mics ( the M ) is facing to the soundsource and the other ones facing to the side ( the S ) . the M ususally is a cardioid mic and the S a figure of 8 .
but other patterns work as well .
the MS needs to be decoded to playback properly .

do a google search or search on the forum youll find a ton of infos bout it !

dont get confused by that 3:1 rule to much !
the 3:1 rule is a rule of thumb where to set up mics .
if you think about a closed mic guitar amp and that mic is like " x " away .
it doesnt make much sense setting the next mic up " 3*x " away .

usually you have a close mic and you want to add a room mic which is ... experiment !

xy on drumoverheads ... i dont like it ( but TRY it ) . the bass response is kinda wired and it sounds a lil to unreal imho .
i like spaced pairs way more . and the only thing you can make sure here is that the mics have the ~ same height .
this is always a compromise and depends a lot on how the drummer is playing .

good luck

[Kiwiburger]

The first picture looks like XY to me. Considering these would be SD condensors that are effectively crossed with about 90 degrees between them. You pan them hard left/right. The basic idea is that close sounds are effectively mono and in phase, so they don't get phasey when mono'd. Because the mic's 'see' different corners of the room, the reflective sounds are very different, giving the stereo spread.

The second picture sort of implies a Mid Side setup, but there is no reason why this could not be XY. It's still two mics, essentially crossed over each other at 90 degrees. Sure, they are vertical rather than horizontal, but that doesn't matter. Sound doesn't obey gravity, so there is no rules about horizontal or vertical.

If you wanted to use the second pair in front of a mic, you would angle the guitar so the close sound was basically equal in both mics. The way they are oriented at the moment sort of implies one is for direct sound, and the other (if set to figure 8) is collecting Side information. To decode this to Left/Right, you would set up a mix of Mid + Side and Mid - Side by using the phase switch on your mixer. Seems funny, but the maths stacks up and you do get a true stereo spread, that cancels to just the Mid mic in mono.

[Kiwiburger]

As for panning from player or audience perspective ... the Golden Rule is do whatever the hell the video is doing at that point in time. Otherwise, toss a coin.

[matt thomas]

those two pictures are both the same (almost)

the capsules of each pair of mics are 90 degrees from each other.

The bottom one has lined up the two capsules on the z axis which may offer better phase response but not neccesarily.

Mathematically a dimension is a direction which can't be described in terms of another dimension (not the official definition, but off the top of my head)

so when you place one mic on the x axis and one on the y axis they theoretically should be picking up waves that are not related to each other as they occupy different spacial dimensions, or the direction of the wave that acts on both mics can be broken down to two unrelated vectors, x + y (note no "z") . This is not absolutely true in practice though because sound waves are longitudinal waves of airpressure, and that pressure can act in a direction other than the direction of the wave.

Ha, I bet I'm just being confusing. simple answer is both of those methods have the diaphrams at 90 degrees to each other.

narco

[davenutz]

the second pair could also theoretically be a blumlien pair if the mics were Figure-8

[Doublehelix]

Both pictures can easily be X/Y, and the second one could be Blumlien or M/S, depending on the pickup patterns.

All three of these techniques are called "coincident pair" miking, which means that the capsules are in the exact same place in space. Since this cannot truly happen in reality, you work to get them as close as possible in space.

The 3:1 rule does not apply here, since that is the whole point of the coincident miking bit....the capsules are in the same place in space (or as close as physcially possible). This technique is designed to give a good stereo image while minimizing phase problems associated with spaced pairs (this is where you want to watch the 3:1 rule).

[nathanvacha]

Originally Posted by dobby12

Ok, so what's the fundamental difference between doing XY mic'ing the way it's shown in the first picture as opposed to the second. Method one seems to be the popular way to setup small diaphragm condensers for XY, and method two seems the preferred choice for LDC's... does it essentially achive the same result? Also, is the 3:1 rule for spaced pairs at all relevant for doing drum overheads? It seems virtually impossible to have the mics between 3 times as far away from each as they are from the drums. Thanks.

Here's the first XY pic and the second will be in the next post.

Doublehelix is exactly right. I'll just jump on the bandwagon and say also that given your questioning, the simple answer is 'yes, they both achieve the same result' -- (if the result you're trying to achieve is a time/phase aligned stereo pair.) if you're putting up an x/y pair, say, of ldc's and one of sdc's, they will probably end up looking like those two pictures (although they could be mounted in a few different ways i guess) there's always more you could learn, but that's as clear an answer to your question as i think i could come up with.

[ajcamlet]

Originally Posted by 5down1up

heres a better view of how to set up XY :

http://images.google.de/imgres?imgur...WE:de%26sa%3DN

thats a pretty cool mic stand for XY- anyone know who makes it?

[C/G]

Originally Posted by ajcamlet

thats a pretty cool mic stand for XY- anyone know who makes it?

Made by Shure. A27M is what the part# looks like to me.

[ghellquist]

Originally Posted by Doublehelix

Both pictures can easily be X/Y, and the second one could be Blumlien or M/S, depending on the pickup patterns.

... except that Microtech Gefell does not make any figure 8 in that form factor. Those are probably M 930 which are large capsule cardioid condensors in a small package (you have to see them) which are truly universally useable.


(there is also a m940 super-card and m950 wide-card).

Well, my two cents.
Gunnar