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1. Re: Simultaneous recording with two digital recorders?

Subject: 1. Re: Simultaneous recording with two digital recorders?
From: "Dan Dugan" dandugan_1999
Date: Tue Jun 19, 2012 10:13 pm ((PDT))
> Has anyone had experience of recording on two independant digital recoder=
s, using say a handclap to provide a sync point, then mixing/layering them =
together later.

I used to do that a lot, first with two Sharp MD recorders, and then up to =
the 2011 season with two LS-10s.

I use the Rich Peet 4-channel surround technique, which is to use a stereo =
array for the front channels, creating imaging across the front panorama, a=
nd two widely spaced mics for the rear channels, intentionally uncorrelated=
 and not imaging. With this arrangement the synchronization accuracy betwee=
n front and rear pairs isn't particularly critical, i.e., doesn't have to b=
e phase accurate as in real multitrack recording, only within a few millise=
conds to work just fine.

I start both recorders and make a "head click" with a party clicker. When I=
'm ready to end the take, usually an hour or 90 minutes later, I make a "ta=
il click."

In post, first I line up the head clicks exactly. Then I go to the end and =
mark where the tail clicks are. The difference between them represents the =
difference in the clocks of the two machines.

I take the front pair as, arbitrarily, correct, and calculate a speed corre=
ction for the rear pair based on the measuring the number of samples in eac=
h head-to-tail clicks span. I enter that correction into Pitch-n-Time as a =
"classic" varispeed change--this changes both pitch and time together, whic=
h is what you want because the two clocks are not at the same rate. Here a =
small compromise is made because PnT allows fewer significant digits than I=
 would like.

I process the rear pair so that the head and tail clicks of both pairs now =
line up (the tail clicks not being exactly on but close). This process is t=
he same as a sample rate conversion, and can be done with very high quality=
 (not the case when making tempo changes without changing pitch).

Finally I offset the rear pair based on my knowledge of the distances to th=
e different mics from the clicker. If I clicked at the front array and the =
rears are 40' out either side, I would offset the rears around 40 milliseco=
nds.

This all is a bit of a chore but the results sound good.

-Dan








"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.



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