Double M/S on seperate 2 channel recorders?


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!


Andrew Spitz

Posted 2010-06-25T08:33:57.993

Reputation: 6 251



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 great...and it's free:

Justin P

Posted 2010-06-25T08:33:57.993

Reputation: 5 344

why would two identical recorders drift? just the internal clocks not measuring time consistently? – Haydn Payne – 2010-06-25T14:28:02.590

Correct. Here's an article that explains drift better. It's about syncing audio to video, but the same applies to two recorders:

– Justin P – 2010-06-25T15:33:12.690

@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 – 2010-06-27T10:10:55.883

two identical recorders would still drift because of the manufacturing tolerances in the clock circuitry. – georgi – 2010-06-27T12:55:38.933 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 P – 2010-06-27T19:23:13.633


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.


Posted 2010-06-25T08:33:57.993


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 – 2010-06-27T10:12:28.207


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.

Matthew Freed Audio

Posted 2010-06-25T08:33:57.993

Reputation: 1 160

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: it's awesome!

– Andrew Spitz – 2010-06-27T10:16:47.953


Last time I did this, I ran into drift issues and reached for Soundhack, trial&error-style.

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Posted 2010-06-25T08:33:57.993

Reputation: 5 521

Interesting, I'll keep that in mind for when I need to change speed ever so slightly. – Andrew Spitz – 2010-06-27T10:15:04.383


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.

Justin Huss

Posted 2010-06-25T08:33:57.993

Reputation: 2 656

Thanks for your input. You're absolutely not polluting the topic! This is what it's about. – Andrew Spitz – 2010-06-27T10:14:03.667