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Re: Simultaneous recording with two digital recorders?

Subject: Re: Simultaneous recording with two digital recorders?
From: "Avocet" madl74
Date: Fri Jun 8, 2012 1:40 pm ((PDT))

I've used two "toy" Tascams together with two pairs of stereo mics.
Syncing the tracks is fiddly and needs more than a clap. With film
recording a clapper board gives accuracy to the nearest frame, but if
you want to match two sounds with a common source, you need better
than millisecond accuracy. That's why I'm saving up for a 4-track.

With timeode recorders, the timing accuracy is better than one frame
per week or around one 10 parts per million. With two free-running
affordable recorders you will get a drift which will produce flanging
from a common sound source. If you don't have a common source, exact
sync is not necessary anyway - just sync to a passing plane or
whatever. :-)

o.1 millisecond across a stereo image gives a noticeable shift in the
image - that's 5 samples at 44.1 Ks/s. One part per million drift will
produce that in around two minutes. Mixed, that produces a comb filter
effect based on 1kHz.

Point to ponder - how far away can a clapper board be before it is 1
frame out of sync? That was one of my questions for trainees. :-)


David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce

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