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I have the opportunity to use a Schoeps double M/S system, but I don't have a recorder with enough channels. I have two 2-channel recorders, and I'm hoping I will be able to get away with this setup and use a clap to sync up the two recorders. If I had two 702 Sound Devices I could link them up without worries, but my second recorder is a Fostex FR-2, which doesn't seem to allow me to link units together.

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My worry is that even the minuscule time difference between the clap being captured by the front M/S and back M/S and recorded on each recorder will create an inaccurate image and maybe cause some phasing and wrong decoding. Are my suspicions valid?

If you advise me against this I'll just rent a recorder with enough channels...

Also, has anyone recorded on this setup? Any tips would be much appreciated!

Thanks!

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6 Answers

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I've tried using two unlinked recorders for things like this. There will be some drift, especially on longer takes (even on identical recorders). If you're doing mission critical takes over 2 minutes, I'd recommend against it, since phase is so critical to proper MS.

I've also tried Double MS with two Sound Devices 722s connected with C-link cables, and it worked great. If you can spring for this set up, you'll be golden. They'll sync up nicely and no claps.

I also highly recommend this plug-in for decoding in post...works great...and it's free:

http://www.schoeps.de/en/products/dms_plugin

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why would two identical recorders drift? just the internal clocks not measuring time consistently? – Haydn Payne Jun 25 2010 at 14:28
Correct. Here's an article that explains drift better. It's about syncing audio to video, but the same applies to two recorders: studiodaily.com/main/technique/craft/f/audio/… – Justin Pearson Jun 25 2010 at 15:33
@Justin good advice, thanks. I'm going to rent a four track recorder. Am I right to think that I only need four inputs? I've played a bit with their plugin, although I haven't used it on actual material. – Andrew Spitz♦ Jun 27 2010 at 10:10
two identical recorders would still drift because of the manufacturing tolerances in the clock circuitry. – georgi.m Jun 27 2010 at 12:55
Andrew...you actually only need three channels: mono front, mono back, and figure 8 side. The plug-in is great and allows you to decode these 3 channels to quad or 5.0. You can also add delay to the rear channels. – Justin Pearson Jun 27 2010 at 19:23
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It is easy to test the drift between the two recordings, start and finish with a clapperboard. Also do a test with the clapperboard, prior to recording on location, from different angles and you can then calculate the delay between the mics and compensate accordingly. Just remember to do free-field (outdoor) tests or the results will be skewed.

Personally I would hire the multi-track recorder, as matching mic pre-amps can be a real pain, you will find that there is a subtle difference in the EQ never mind the noise floor.

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You're right about the pre-amps, i didn't think about that although I'm sure that would have been the next question on my mind. – Andrew Spitz♦ Jun 27 2010 at 10:12
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Out of curiosity, what are you recording that two M/S setups are beneficial?

On the topic of using different recorders, I would highly recommend against it. The differences in sync, preamp sounds, etc will drive you bonkers. You're far better off using a 4 channel recorder with identical preamps.

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Thanks, I've decided to just rent a four track. I was just hoping and thought I'd ask people. The double M/S is great for surround recordings. You can then decode them using Schoeps' plugin: schoeps.de/en/products/dms_plugin it's awesome! – Andrew Spitz♦ Jun 27 2010 at 10:16
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Last time I did this, I ran into drift issues and reached for Soundhack, trial&error-style. alt text

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Interesting, I'll keep that in mind for when I need to change speed ever so slightly. – Andrew Spitz♦ Jun 27 2010 at 10:15
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I never used a Double M/S system but I agree with Iain McGregor.. I think that matching the pres can be your biggest problem, the syncing it's a matter of adjusting the file in the time-line and making the proper stretch to correct the sample rate floating.. The different pres will result in subtle transients differences that can be really hard to match!

Just curiosity, which mic have you left to the other recorder? Or have you recorded M/S on both recorders switching only the M mic?

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Haven't yet recorded anything. But all mics will be Shoeps: schoeps.de/en/products/categories/doublems so the front will have a Mid and a figure-8 and the back will have the same setup. Is that what you mean? So if I where to record on two recorders (which I decided not to) I would have one M/S per recorder – Andrew Spitz♦ Jun 27 2010 at 10:20
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What follows is only assumptions of what could go wrong.

Well, am I being naive when I say it'd just be a matter of nudging the audio to line up the recordings? In theory that'd seem to work, but I guess you need to take into account the clocks of your two recorders not being synced, not sampling the audio at the same exact time and your recorders not using the same preamps.

Now let's hear/read from others' experiences! Hope I'm not polluting the topic here... just trying to participate by discussing.

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Thanks for your input. You're absolutely not polluting the topic! This is what it's about. – Andrew Spitz♦ Jun 27 2010 at 10:14

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