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Re: Questions - Spaced Omni Pairs

Subject: Re: Questions - Spaced Omni Pairs
From: Dan Dugan <>
Date: Mon, 10 Jan 2005 21:45:11 -0800
DAN DUGAN:
>  >>  Of course they drift, about one foot (sound travel time) per minute
>>>   is typical. But if the rear pair is fifteen to forty feet away from
>>>   the front pair, that won't matter. As Rich Peet said, effectively
>  >>  decorrelated.

>ROB DANIELSON:
>Bet I'm missing something here. As long as the signals are not mixed,
>wouldn't a header change be enough?   44 100 / 44 087 =3D 1.00029487.
>Think anyone could detect such a tiny pitch change?

I've never tried that; equivalent to just adjusting the tape speed a
little. But doesn't it depend on the software that's reading the
header being able to compensate for a non-standard sample rate file?
The software has got to do a resampling to do that, like a sample
rate conversion.

>With +15 feet mic spreads and two MT-90's last summer, I was
>consistently getting ~1/30 second  or ~33ms differences with 80
>minute takes (digital transfers).

Something wrong with the numbers; 1ms/30 seconds is 2ms/min, 160ms/80 min.

>Perhaps my recorders "speeds" were
>closer matched,

Must have been. I've been using two different models.

>but I was able to get no more than ~17ms difference
>by aligning the head slates, cutting the longer file in the middle,
>dragging the 2nd half backwards until the tail slates matched and
>cross faded the over-lap. MD drift did not surface as an issue at
>all; there were only a few situations where some additional sliding
>seemed to make a better image. Rob D.

Sounds good.

-Dan Dugan


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