Topic: DR-680 M/S Decoding

[acidjack]

Has anyone experimented with the M/S decoding feature on the 680?  How exactly is setting that different than just recording the normal 1/2 3/4 5/6?  Does the M/S setting output three files (one M and then two sides)? 

I haven't played around with M/S at all, but since the 680 has the feature, I figure if it saves a step in post, I'd like to try it. I've read Page's explanation on how to decode m/s in Audacity and understand the general principles of the technique, but beyond that, I don't know much.

[H₂O]

I don't know about the 680 but M/S is only two channels - 1 Mid (i.e. Sub, Card, Hyper) and 1 Side (Figure-8 ).   There is Double M/S which is 3 channels (added a back channel) for use with surround and not stereo.

Usually there is two parts an M/S headphone decoder (so you can adjust levels while recording) and M/S decode to output or recorded tracks (which would be Stereo).

My guess on the 680 is that M/S would decode to the MIX tracks (tracks's 7-8) by default - but I don't own one.

 

[DigiGal]

I don't know about the 680 but M/S is only two channels - 1 Mid (i.e. Sub, Card, Hyper) and 1 Side (Figure-8 ).   There is Double M/S which is 3 channels (added a back channel) for use with surround and not stereo.

Usually there is two parts an M/S headphone decoder (so you can adjust levels while recording) and M/S decode to output or recorded tracks (which would be Stereo).

My guess on the 680 is that M/S would decode to the MIX tracks (tracks's 7-8) by default - but I don't own one.

A generic matrix will take the separate Mid and Side components and create a stereo mix as follows:
Left = Mid + Side
Right = Mid + (-Side) = Mid - Side

With M/S you also have complete mono compatibility for broadcast because the side signals will cancel out when left and right are combined:
L + R = (M + S) + (M - S) = M + S + M - S = 2M

[yltfan]

The 680 can record both ways, decoding on the fly, or recording both for decoding later. When having the 680 do the decoding, you can adjust the mid vs. side on the fly, which I thought was pretty cool.

[H₂O]

Can the 680 decode the headphone output only?  Can the 680 decode to the mix tracks and still record the raw M/S on to another set of tracks?

[acidjack]

^^ This is kind of what I'm getting at. I don't want to decode on the fly - would rather do it in post when I am somewhere that I can do a bit of critical listening...

[DigiGal]

^^ This is kind of what I'm getting at. I don't want to decode on the fly - would rather do it in post when I am somewhere that I can do a bit of critical listening...

Q.E.D.

You will still only record 2 channels with a MID/SIDE setup but instead of LEFT and RIGHT they will be the MID and SIDE direct components. 

Be sure to record the SIDE which is figure-8 (a.k.a. bidirectional) mic on Channel 2 and record your MID mic (this pattern is optional) on Channel 1.  Your DAW's software or plug-in can handle it from there.

This is essentially what the software is doing...
The SIDE always a figure-8/bidirectional uses only one record channel when you are recording.  It will be split in post as SIDE (+S) and Inverse of SIDE (-S) this is simply a polarity inversion of the SIDE bidirectional mic which has 2 lobes one facing each of the sides.  These 2 derivatives are each then mixed with the MID providing you the final LEFT and RIGHT Channels (which are SUM and DIFFERENCE).  Thus varying the MID and SIDE playback levels ultimately varies your desired stereo width in post. 



A generic matrix will take the separate Mid and Side components and create a stereo mix as follows:
Left = Mid + Side
Right = Mid + (-Side) = Mid - Side

With M/S you also have complete mono compatibility for broadcast because the side signals will cancel out when left and right are combined:
L + R = (M + S) + (M - S) = M + S + M - S = 2M

[H₂O]

^^ This is kind of what I'm getting at. I don't want to decode on the fly - would rather do it in post when I am somewhere that I can do a bit of critical listening...

I have always decoded M/S in post as you are not going to have an idea of the room mix until the band starts.  It also give's you the option of "mixing in post" you can bring the sound closer in and loose a bit of the stereo affect or go for more stereo and less presence (obviously this will depend on placement in the room).  Software makes it very easy and quick to do this.

In the past (i.e. 10 years ago) it may have been easier to do the mix on the fly as computers where much slower, software was not free to do this (to my knowledge), and storage was at a premium.


When you run MS Mid must be channel 1 and Side Channel 2 also (so you can effectively get a mono source off channel 1 - old skool I guess).  Also the 0 degree mark should be pointing left on the figure 8 (red dot on a Schoeps mk6 or mk8 - or I believe the Front of the AKG 414 you have listed in your sig).

It would be neat if the 680 can record both the M/S dematrixed and raw channels at once just to see how much of a diff post versus on the fly really makes.

[rastasean]

the r44 has a ms setting in it as well. Not sure if it is advanced of the dr680 but since you're decoding at home, you would just need the fig 8 and card mic.

[phil_er_up]

I am interested in how this works and was wondering the following:

Where would you place your mics to get the best effect from the M/S decoding feature on the 680?
Does it matter what mics types (omni, cards, subs, hypers etc) you use for M/S decoding feature on the 680 to sound the best?
(Just looking for a general idea here - nothing exact due to each venue is different)

Is there any recordings with using M/S decoding feature on the 680?

[DigiGal]

Does it matter what mics types (omni, cards, subs, hypers etc) you use for M/S decoding feature on the 680 to sound the best?
(Just looking for a general idea here - nothing exact due to each venue is different)

You just use a figure-8/bidirectional for the SIDE mic connected to Channel 2 of the recorder. [The SIDE mic lobes point to both the Left and Right sides, not directly at the sound source]

You can use your choice of (card, sub, omni, hyper, shotgun, figure-8) for the MID mic connected to Channel 1 of the recorder.  Card is the most common pattern used for MID.  [The MID mic points to the center of your sound source]

[rastasean]

Must the mid, say cardioid, be a small diaphragm or can it be a large diaphragm? Does this matter of the size diaphragm used for side.
What about side, can you use a large diaphragm figure 8 mic and small diaphragm mid? OR is it best to use equal size diaphragm mics?

 

[ghellquist]

Must the mid, say cardioid, be a small diaphragm or can it be a large diaphragm? Does this matter of the size diaphragm used for side.
What about side, can you use a large diaphragm figure 8 mic and small diaphragm mid? OR is it best to use equal size diaphragm mics?

Use whatever gives the best result. There are no rules that overrides the old saying that if it sounds good it is good.
The pattern I tend to like is to select a mid mic that gives the very best mono sound possible. Then I add a really good figure 8 with as little back-to-front difference in sound, preferrably a Sennheiser MKH30 or similar calibre mic. Large size side mics can work, but not necessiraly as good. A good band symmetrical band mic ( say a royer SF1 ) is a possible choice.

// Gunnar

[Ozpeter]

If you  are going to be post-producing on a typical DAW, it doesn't matter if you de-matrix the MS signal to XY in the recorder.  There are plenty of free plugins which will put it back to MS, then vary the width, and re-dematrix it - eg Voxengo MSED.  For that matter, you can use a any stereo mic, (not MS), then convert to MS, play with the width, then dematrix, in your DAW using such a plugin.

In theory - some say - there's no theoretical difference between a dematrixed MS recording and te equivalent XY.  Personally, I think there is a difference due to having the centre of the stereo image right on axis of the "M" mic - but you could spend a lot of time kicking the math of that around to prove or disprove it, which I'm not about to do!

[Gutbucket]

Can the 680 decode the headphone output only?  Can the 680 decode to the mix tracks and still record the raw M/S on to another set of tracks?

I don't know the answer (guessing no), but that would be a cool way to monitor both the direct feeds and the decoded stereo.