Topic: A device (or mixer) that monitors in decoded M-S but records discrete tracks

[Ozpeter]

I do a lot of recording for film and radio and am looking to upgrade to a Sennhieser M-S setup. But I need a new recording device too (I have a Sony D-50) and really want one that allows me to MONITOR in stereo (in other words, the M-S signals decoded) but RECORD the mid and side as discrete tracks (in other words, the M-S signals un-decoded).

I'm struggling to think of a good reason for recording an MS signal as MS.  I can think of at least one reason why it's unwise but no reasons why it should be done.

[runonce]

I do a lot of recording for film and radio and am looking to upgrade to a Sennhieser M-S setup. But I need a new recording device too (I have a Sony D-50) and really want one that allows me to MONITOR in stereo (in other words, the M-S signals decoded) but RECORD the mid and side as discrete tracks (in other words, the M-S signals un-decoded).

I'm struggling to think of a good reason for recording an MS signal as MS.  I can think of at least one reason why it's unwise but no reasons why it should be done.

Thats not what he's doing...

[SonoOtoSound]

Yeah, my reason for wanting to monitor in stereo is basically what runonce said. In addition, I'll be using a Sennheiser MKH 50 for the mid, which is a little narrow and reportedly can sometimes create some weird, blank spots in the stereo image for some sounds. It's pretty easy to fix, just by getting the right distance from your source but you can only do that if you're listening to a decoded stereo mix.

The reason I'm recording it as two discrete tracks (the mid and the side) is so that I have total control *afterwards* of how wide or narrow I want the sound to be. If you record in stereo you're stuck with whatever amount of width you've chosen and I don't want to chose that in the field, because sometimes there is no *one* correct amount. For film work, sometimes you want the exact same sound in two or three different perspectives to match different shots in the film.

[Ozpeter]

The reason I'm recording it as two discrete tracks (the mid and the side) is so that I have total control *afterwards* of how wide or narrow I want the sound to be. If you record in stereo you're stuck with whatever amount of width you've chosen and I don't want to chose that in the field, because sometimes there is no *one* correct amount.

I think you're not clear on the relationship between MS and XY.  They are freely interchangeable in either direction.

If you record discrete MS, in postproduction in a DAW you normally use a VST 'effect' to handle the conversion from MS to XY, and that effect will indeed have controls to vary the proportion between mid and side to allow you to choose the effective width.  But even a freeware MS VST effect (eg Voxengo MSED) will have modes to convert XY back to the original MS, and XY > MS > XY ("inline" mode) allowing the width of an XY recording (whether originated from an XY pair or an MS pair) to be varied in post production.  MS and XY recordings can be width-varied in exactly the same way - you don't have to have the original M and S signals to do it.

Recording an MS pair as MS gives rise to the monitoring problems you are encountering and in some contexts carries the risk of someone not realising the format of the recording and using it 'as is' with very undesirable results.  Converting from MS to XY at the time of recording is, in any context I can think of, a better practice and it makes no difference to the ability of varying width in post production.  That's why I've been recording that way using my Sennheiser pair for about 25 years and I have never once wished I'd recorded discrete MS.

[SonoOtoSound]

If you record discrete MS, in postproduction in a DAW you normally use a VST 'effect' to handle the conversion from MS to XY, and that effect will indeed have controls to vary the proportion between mid and side to allow you to choose the effective width.  But even a freeware MS VST effect (eg Voxengo MSED) will have modes to convert XY back to the original MS, and XY > MS > XY ("inline" mode) allowing the width of an XY recording (whether originated from an XY pair or an MS pair) to be varied in post production.  MS and XY recordings can be width-varied in exactly the same way - you don't have to have the original M and S signals to do it.

I figured there was a way to convert XY > MS (since doing a mono sum of the XY would give you the Mid - I assumed there would be a pretty easy way to then get a discrete Side signal too) but I didn't realize that a plug-in could allow you to go XY > MS > adjust the level of side and then > XY. Can it do all of that in one step??? Or do you have to use the plug-in to convert the XY to MS and then run the plug-in again on the new MS version of the audio to bring it back to XY?? From your description it sounds like it can do all of that in one step, which would be really impressive. Thanks for pointing that out.

Still though, I'm leaning towards recording it to two discrete tracks because I'll be using this setup primarily to record FX for film and I think that very frequently I'll just want to use the Mid signal (maybe 60% of the time). So having a separate M and S right off would be advantageous to me. I'm a total newbie to M-S, so your 25 years of experience is nothing for me to discard. Do you record all kinds of stuff this way, including FX? I'm very curious what you think about recording discrete MS if it would be primarily for FX (hence, having a mono Mid file right off the bat would be advantageous)

Thanks for your help - I really appreciate hearing your opinion!
Mark

[Nick's Picks]

The reason I'm recording it as two discrete tracks (the mid and the side) is so that I have total control *afterwards* of how wide or narrow I want the sound to be. If you record in stereo you're stuck with whatever amount of width you've chosen and I don't want to chose that in the field, because sometimes there is no *one* correct amount. For film work, sometimes you want the exact same sound in two or three different perspectives to match different shots in the film.

but, thats my point exactly.  do it in post.  no need to monitor it at all to hear what it might sound like in realtime (decoded signal to your headphones, while reccording raw m-s).  You're still going to mix it in post after the fact, so why worry about the "real time sound" ...when the finished product is going to be different any way.  Trust me, having done this many, many times..., what you think sounds great on the fly is never as good as what you mix in post in a controlled environment.   Plus, if you record a mixed M-S signal as stereo L/R, you can still bring it back to raw-M-S and remix it.  There is no "one chance" with Mid-Side.  No matter how the stream is recorded.

[Javier Cinakowski]

I gotta imagine there is some degradation from going back and forth between M/S and L/R and vice versa.   Wouldn't the audio editing software or plugin have to "recreate" the .wav during each process.  It isn't like we are doing this in the analog realm, wouldn't there be some degradation or digital artifacts every time this is done?

I just don't see how this could be a free lunch.  It isn't like you can EQ (destructive editing) a recording and then EQ it back without degradation of the product...

Am I missing something?

[page]

The reason I'm recording it as two discrete tracks (the mid and the side) is so that I have total control *afterwards* of how wide or narrow I want the sound to be. If you record in stereo you're stuck with whatever amount of width you've chosen and I don't want to chose that in the field, because sometimes there is no *one* correct amount. For film work, sometimes you want the exact same sound in two or three different perspectives to match different shots in the film.

but, thats my point exactly.  do it in post.  no need to monitor it at all to hear what it might sound like in realtime (decoded signal to your headphones, while reccording raw m-s).  You're still going to mix it in post after the fact, so why worry about the "real time sound" ...when the finished product is going to be different any way.  Trust me, having done this many, many times..., what you think sounds great on the fly is never as good as what you mix in post in a controlled environment.   Plus, if you record a mixed M-S signal as stereo L/R, you can still bring it back to raw-M-S and remix it.  There is no "one chance" with Mid-Side.  No matter how the stream is recorded.

I think his desire stems from making sure he's setup correctly, it's the same argument I see for monitoring anything in the field; you want to make sure you're not getting absolute trash.

[Nick's Picks]

its field recording...there is only so much that you can do in "real time".  If the sound sucks, you'll polish your turd much better sitting at your desk.

[Nick's Picks]

I gotta imagine there is some degradation from going back and forth between M/S and L/R and vice versa.   Wouldn't the audio editing software or plugin have to "recreate" the .wav during each process.  It isn't like we are doing this in the analog realm, wouldn't there be some degradation or digital artifacts every time this is done?

I just don't see how this could be a free lunch.  It isn't like you can EQ (destructive editing) a recording and then EQ it back without degradation of the product...

Am I missing something?

I hear ya, but I guess it comes down to math at its core.  And that is absolute, so no loss.

[Gutbucket]

Plugins make it easier in the digital realm and do it better without potential artifacts (no noise, no gain balancing issues) than the analog way of patching channels and inverting polarity through a mixer.  Plus they are far less of a PITA!

Yes, some plugins have two matrices so you can input X/Y, adjust M/S ratio and output X/Y again all in one plugin.  I think Voxengo's MSser or whatever it's called does that, if not other free ones do.  Some DAWs have that functinality built into advanced pan function on stereo tracks- Samplitude does.

There are a few good reasons for recording the raw M/S. Quick access to the mono mid without decoding is probably the main one.  I did so last week for that very reason. Ability to vary the stereo spread using the playback M/S decoder built into the recorder without offloading the files into a DAW is another. 

[noahbickart]

get in touch with mshilarious. He now has a m-s decode board option for the littlebox. he is making me one with 2 sets of rca pairs, one undecoded (e.g. m-s) and the other decoded (e.g. x/y). I've got outboard headphone amps for monitoring, but he can also build a headphone amp into the unit with a switch for the monitor feed. See naiant.com

And Nick, I think the point is that he isn't a OTS concert tapir like you. He is doing pro work with the pair on a boom. He needs to monitor in real time to know where to place the microphones- something over which he does have full control.
-Noah

[George2]

I have the original MS38 from AEA. Line Level. No headphone out. Just one knob. You would have to connect to your line out from recorder and then connect MS38 to headphone amp.

[Gutbucket]

Note the matrixed to mono mid cat paw. 

[George2]

Cats come with.. all 3 of them.. no charge!