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Re: The new nagra seven and 4 inputs

Subject: Re: The new nagra seven and 4 inputs
From: "Dan Dugan" dandugan_1999
Date: Fri Feb 28, 2014 8:54 pm ((PST))
> Could you use two stereo recorders
> running together?

<snip excellent explanation of why this won't work>

> Now someone write in and say that they have done this successfully. :-) I=

> would reply "always experiment", but not if it is going to cost money.

Can't resist, David!

I did a lot of four channel nature recordings on mini-discs and LS-10s befo=
re I could afford a 4-track. It's not possible to do a real phase-accurate =
multitrack recording this way, but if you use a mic array where phase betwe=
en the front and rear pairs doesn't matter, then you can make it work well.=
 I'm talking about recordings that are over an hour in length.

I used the "Rich Peet" surround technique: choose your favorite imaging ste=
reo array for the front channels; MS, Jecklin Disc, ORTF. Run the left rear=
 forty feet out to the left, and the right rear forty feet out to the right=
 (good for being on a trail). One stereo recorder does the front stereo arr=
ay, the other the wide-spaced rear pair.

In this array the front channels image, the rear channels are uncorrelated.

You click a party clicker at the head of the recording, and another click n=
ear the tail. Click in the same location for the head and tail clicks. Note=
 the location of the clicker in relation to all the mics. Clicking in the c=
enter near the front array makes things simpler, but I did it successfully =
from my sleeping bag off to one side too.

In post, line up the head clicks of the front and rear stereo pairs. Note h=
ow far apart the front-to-rear tail clicks are in milliseconds. Calculate t=
he difference in speed and vari-speed* the rear pair of tracks so that the =
tail clicks match the fronts within a few ms. This step corrects the speed =
difference of the two recorders. Now slip the rear channels to fix the time=
 of arrival of the clicks given what you know about the location of the cli=
cker. Estimate one ms per foot. This step compensates for the geometry of t=
he array.

Given that the rear channels are 40 ms separated from the fronts, accuracy =
within a few ms will be fine. This worked very well for me. But I was very =
happy to not have to do the post procedure any more when I got a 4-track.

-Dan

* Use a simple resampling varispeed plug-in. That will preserve fidelity. D=
o not use the complex time-shifting algorithms that change tempo while pres=
erving pitch. They can add artifacts and distortion. You want to change pit=
ch and tempo both. In the Pitch 'n Time plug-in, that setting was called "c=
lassic."








"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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