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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: goldenhours on May 07, 2013, 11:48:53 PM

Title: MS Stereo Linking on SD MixPre-D
Post by: goldenhours on May 07, 2013, 11:48:53 PM
Hi,

This may be an obvious question but I'm trying to figure this out as I'm planning on getting a MixPre-D for my field recording rig and the way it's described is not quite clear to me:

Using the MixPre-D's MS Stereo Linking function, are the mid and side channel being recorded separately, i.e. one is still able to change the stereo 'spread' and polarity etc. afterwards, or does it actually mix them down to a stereo track whereby the relationship between mid and side is being fixed?

What I'm looking for is to be able to 'monitor' the MS in the field (like the Sound Devices recorders allow) but keep the raw M and S files separately to manipulate in post.

Hope this makes sense.
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: George2 on May 08, 2013, 12:27:16 PM
Hey... nothing gets recorded on the Mixpre-D. ;D
When linking for MS, the Left and Right outputs are L-R stereo (actually mix them down to a stereo track whereby the relationship between mid and side is being fixed)
If you want to record the M and S separately, don't link.
The Headphone out is what is coming out the main, computer, or return....there is no M/S monitoring function.

Title: Re: MS Stereo Linking on SD MixPre-D
Post by: goldenhours on May 08, 2013, 12:39:24 PM
Hey... nothing gets recorded on the Mixpre-D. ;D
When linking for MS, the Left and Right outputs are L-R stereo (actually mix them down to a stereo track whereby the relationship between mid and side is being fixed)
If you want to record the M and S separately, don't link.
The Headphone out is what is coming out the main, computer, or return....there is no M/S monitoring function.

Thanks for the info, that's kind of a deal breaker for me... I don't really get the point of having a function like that (at least for my purposes)... Isn't it one of the major advantages of recording M/S that you can tweak the stereo image afterwards?

Any suggested alternatives in terms of quality of preamps and price to feed my M/S mics into my Nagra SD? With or without M/S monitoring...
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: DigiGal on May 08, 2013, 12:45:26 PM
If you want to record the M and S separately, don't link.

You can link them as X/Y Stereo Link which will effectively maintain a 1:1 discreet M/S ratio, you then matrix to Left - Right with desired width in post. 

From the MixPre-D manual "X/Y Stereo Link When in X/Y stereo link operation, Input 2’s Pan Switch controls the stereo image (L: Input 1 = Left, Input 2 = Right; C: Both Inputs in both channels; R: Input 1 = Right, Input 2 = Left). Channel 2’s Fader controls the overall level of the stereo pair. Input 1 and 2’s High-pass Filters continue to act independently of each other. When linked, Input 1 and 2’s Limiters are also linked."

As far as monitoring there's no need to get hung up on monitoring in stereo when you'll perform the stereo matrix in post.  A common monitoring technique is to make a headphone adapter cable that puts the (mid) channel to both ears to better monitor the on-axis component while in the field.

Note: If you did record a stereo matrix of your Mid/Side mics from the MixPre-D you could convert it back to the discreet Mid/Side components in post.  This technique would then allow you to matrix it again in post to achieve the stereo width desired.  You are however going through extra encode/decode steps that would not be necessary if you record the discreet Mid/Side components directly.
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: George2 on May 08, 2013, 12:52:11 PM
I have the Mixpre-D main outs going to Nagra SD.
I use the M/S link function, and record that way. If you make the mix slightly on the wide side while listening on headphones, later you can pan the L-R toward the center a bit to reduce the stereo image in post... so you do have a bit of control.
It's very easy to use.

I think the SD302 mixer has the M/S monitoring on the headphone selector.
But the Mixpre-D is easier to use, as you don't have to deal with the gain trim pots like on the SD302.
Mixpre-D is very fast to setup and is repeatable.
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: goldenhours on May 08, 2013, 01:01:11 PM
Thank you both, there's already several options I hadn't thought of.

I have the Mixpre-D main outs going to Nagra SD.
So you use the XLR outputs on line level via the Nagra adapter cable, right?
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: George2 on May 08, 2013, 01:25:08 PM
Yes, XLR Line level out from Mixpre-D. I made the cable, as I didn't want to pay for the Nagra XLR stereo cable.
I used the mono XLR mic cable that came with the SD. Opened up the plastic clip-on, and there are 3 extra wires in there for the line-level input side of the SD.
I use a more flexible Mogami mic cable and connected to these 3 leads.. (THEY ARE REALLY THIN WIRES!)
On the XLRF side for the mixpre-D, I wired it as SD says to for unbalanced output... don't connect or use pin 3 on the XLR.
When turning on the -20dBfs slate tone on the Mixpre-D, the input control on the Nagra has to be turned completely down, and the tone comes into the Nagra at about -19dBfs.
I thought there might be some distortion, possibly over driving the input of the Nagra.. there isn't any!
Title: Re: MS Stereo Linking on SD MixPre-D
Post by: noahbickart on May 09, 2013, 01:35:12 AM
For what it is worth, I run m/s but record a L/S signal (naiant littlebox with built in m/s decode> m10). I use an inline AU plugin in post to adjust the MS ratio.