Re: arsclist Transfer of multiple copies, was: Full 3-D mapping of groove?

["Doug Pomeroy" <pomeroyaudio@xxxxxxx>]

> Date: Tue, 10 Dec 2002 21:46:06 +0000
> From: Don Cox <doncox@xxxxxxxxxxxxxx>
> Subject: Re: arsclist Transfer of multiple copies, was: Full 3-D mapping of
groove?
>
> On 10/12/02, Doug Pomeroy wrote:
>
<SNIP>
>
>> It is gratifying to learn that CEDAR is thinking about this subject.
>> It seems to me their existing Azimuth Corrector is actually part of
>> the solution, as it can correct very small timing errors between two
>> sources; what's needed is a much more powerful processor to deal with
>> larger corrections over time.
>
> Yes, but the Azimuth corrector is not changing pitch.

I beg to differ. It does change the pitch, but at the level of a few
milliseconds, which the ear cannot hear as a pitch shift. But that's
what it is.  As I said, what's needed is a processor which will do
this with much larger timing differences.
>
>
>> Such a processor could sync transfers made at different times and on
>> various turntables, greatly simplifying the process and increasing the
>> potential usefulness of this technique. (Application of CEDAR
>> noise-removal processing to the various source transfers, before
>> syncronization, would no doubt contribute to optimum results.)
>
> I suspect it would be better to do the correlation first - noise
> reduction will remove low level sounds which might otherwise be
> detected.

I am very familiar with what CEDAR removes. How much the "low level
sounds" would be required for the operation of the syncronizer is an open
question, but I know the underlying waveform is not significantly changed
by gentle CEDAR de-clicking.  However, I agree with you: what I should have
said is that the CEDAR processing could be done after syncronization, but
before the sources are actually combined in mono.
>
>
>> The theory also states each doubling of the number of sources improves
>> the s/n by another 3 dB. So, *four* copies of the same recording could
>> produce a whopping 6 dB improvement!
>
> If it's a mono recording, you have two copies on each disc.

Well, sure.  But the theory refers to the L+R output of one mono disc
being added to the L+R of another.  (Making sure the L+R is optimized
in each transfer is of course important, as always.)
>
>
<SNIP>
>
> Regards
> - --
> Don Cox
> doncox@xxxxxxxxxxxxxx
-
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