You rang? Yes sir, the RSM 191 is a glorious sounding mic. And worth every penny.

But to the point. There are NO STEREO SHOTGUNS. There are Stereo/Shotgun mics that are EITHER a shotgun or a stereo mic, but not both at the same time.

Dialog is almost always recorded in mono for features, frequently to both tracks of a DAT, Nagra or solid state recorder. That's two track, but the same audio on each track.

A variation commonly used is to split track two mics, one to each of two tracks. During postproduction, the non-spoken into mic track is muted. This prevents Actor 'A's voice from bein heard on Actor 'B's mic. If it were heard, the phase smearing (time difference) would be objectionable. More tracks allow for more discreet mic to be recorded to each track.

All the beautiful stereo and surround stuff you hear in theaters is done in post.

Regards,

Ty Ford

thanks barry it is clear now
thanks ty ford for your inputs, I really start to understand this issue,

alkim.

Good luck, and let us know how it goes!

Anybody,
I want to get a M-S mic but will I be able to work with it in FCP?
FCP seems to have LR stereo only. I do have Soundtrack Pro but see no mention of M-S in the manual.

Michael Hamilton

Don't know FCP or Soundtrack so speaking generically here and assuming you've recorded using two separate mics in an M/S coincident array, a cardioid mid-mid and a figure-8 side mic. The resulting recording is two tracks, a mid track and a side track. As I understand it, you'd need to setup three mono tracks in your NLE. The 1st track is the cardioid mid-mic "M" The 2nd track is the figure-8 side-mic "+S" For the 3rd track you duplicate the 2nd and invert its phase to give inverted side-mic "-S" Assuming the "front" of your figure-8 mic was pointing to the left when you recorded, in your mix you send M+(+S) to the left channel and M+(-S) to the right. Juggling the relative volume of the tracks adjusts the apparent width of the stereo stage. Some mixers such as the Sound Devices 442 actually have the matrixing circuitry to do that mix on the fly built-in so as you're recording you can feed an M/S mic pair to the mixer inputs and get a conventional L/R channel output from the mixer to the recorder.

Steve's got it right. M/S might be in FCP, but I'd personally feel squeamish about working on it there. I'd prolly export it to Pro Tools and then bring it back in.

Very Good Question.

Ty Ford

but if you're talking about a "m/s" mic, in which a single mic contains both elements, (like the sony 957 or the shure vp88,) the mic does the matrixing for you. it gives you left and right stereo outputs, and you capture it into fcp (or whatever) like any stereo source.

Yes, but in doing so you can't manipulate the stereo breadth as you can with M/S.

Regards,

Ty Ford

Thanks for your answers, they are very helpful.
I shoot documentary style outside alot and thought an M-S mic would be a great thing to have. But due to FCPs limitations I guess I might as well save my money and get a regular stereo mic.

Michael Hamilton

Michael,

Don't let my limitations stop you. You might be able to get it to work by exporting to Soundtrack Pro. I don't know. I haven't had to figure that out yet.

Regards,

Ty Ford

Thanks Ty,

I'm unclear about something. When you say that you can't manipulate the stereo breadth as you can with M/S, are you speaking of the difference between two mics in a coincedent array versus audio from a single M-S microphone?

Michael Hamilton

Nate,
When the M-S mic does the matrixing and gives me LR stereo output does
the mid become one channel and side become the other? If so will I be able to change the side from - to + per Steve House in my nle even though the side comes into it as one channel?

Michael Hamilton

Hi Mike,

Yes. In M/S you have the mono Mid mic you can always go to. That a bit different than monoing an XY because neither mic in XY is pointed directly at the source, (if there is a single source.)

M/S, when dematrixed through three channels on a console as elegantly described earlier in this thread by Steve House, lets you go from mono to very wide (and usually noisier), depending on the shot itself. That's done in post after they decide which shot they may be going with. You get a wide shot, you might want a wider sound field. If you're on a closeup, the typical way to do ambi is to make it a more narrow stereo spectrum.

Of course, over in France, I have learned they sometimes do dialog in M/S, which means relying on the Mid for the meat and adding the Side for the potatoes (pomme de terre?). I'm not sure what that sounds like in scenes where there a lot of boom movement. It might get pretty wacky. OTOH, maybe the boom technique changes to put the mic sort of in the middle of the action and expectng the Side to cover anyone not directly under the mic. If you weren't in MS and expecting to use the Side channels, you'd be missing some dialog (or it would be off axis) from anyone you weren't pointing the Mid mic at.

Z'at make sense?

Regards,

Ty Ford

right. ty's talking about 2 mics in an m/s array, as opposed to mics like i mentioned (which are really 2 mics in one handle.)

the sony i talked about does what steve described. the "left" and "right" it gives you are the mid + side, and the mid + phase-reversed (-) side. it's got an "angle" switch (wider or narrower) which basically chooses the faux-stereo spread before you start recording. if you wanted to further manipulate the spread after recording, it would be a pain.

let's see...if you summed the left and right channels, the + and - side would cancel itself out, leaving you with just the mid. put that aside for a second and duplicate it. go back and take the copy of the left channel (you copied it before summing it with the right.) now take one of your mid tracks (l+r summed,) and phase-reverse it. i'm pretty certain you can do that in soundtrack pro.
okay, now add the -mid to the original "left." this will cancel the mid, leaving you with just the side.

so you've basically un-matrixed the faux left and right to get back to the actual m and s signals that the mic elements picked up. (or a weird-sounding mush of phase cancellation and digital artifacts.) i have no idea if this would actually work, but it seems like it makes sense on paper.

just thinking about that makes my head hurt. the better m/s mics (or using a pair...) will give you the actual m and s outputs, leaving you to deal with the matrxing yourself, like barry said.

My head hurts now two. I need time to digest this but am really greatfull for everyones contributions.

Thanks
Michael Hamilton