It may not be so hopeless. The new Celemony software claims that it can
eliminate wow and flutter. I wonder if 2 records processed in this
manner would fit the requirement. Perhaps Celemony could be modified to
run 2 files simultaneously for this purpose.
On 6/22/2012 10:06 AM, Aaron Z Snyder wrote:
> These contributions from Ted Kendall and Doug Pomeroy have convinced me that
> all attempts at reconstructing "accidental stereo" from two
> simultaneously-recorded 78's with separate mic sources will be futile ---
> that is, unless someone can construct an algorithm to keep the separate
> sources in a continuously stable phase relationship. I've already looked at
> a couple of these reconstruction attempts and observed that even short-term
> phase stability is completely absent. The net result is pseudo stereo even
> if there's genuine spatial information shared between the two sources. I
> take no pleasure at all in coming to this conclusion, but that's reality.
> Aaron Z.
>> -----Original Message-----
>> From: Association for Recorded Sound Discussion List
>> [mailto:[log in to unmask]] On Behalf Of Doug Pomeroy
>> Sent: Friday, June 22, 2012 10:30 AM
>> To: [log in to unmask]
>> Subject: [ARSCLIST] multiple copies for surface noise reduction, was Re:
>> from pictures
>>>> Date: Wed, 20 Jun 2012 10:44:42 +0100
>>>> From: Ted Kendall <[log in to unmask]>
>>>> Subject: Re: audio from pictures
>>>> Chris Hicks of Cedar did his doctorate on just this question of
>>>> multiple copies. When the algorithm could be persuaded to work, the
>>>> results were much as you would expect - enhancement of the correlated
>>>> wanted signal and reduction of the random noise. Unfortunately,
>>>> pulling the recordings into good enough sync for artifacts to be
>>>> negligible was a frustrating and difficult business, even with
>>>> recordings made one after the other (by me, as it happens) on the
>>>> same kit on the same settings on the same afternoon, with meticulous
>>>> centring. The minute geometrical differences between different
>>>> laminated pressings were enough to throw things continually out of
>>>> register. The example produced, however, is a tantalising glimpse of
>>>> what might one day be possible.
>>>> Whenever I do a master of the QHCF Decca of "Souvenirs", I use three
>>>> copies from the shelf - one for the very start, one for most of the
>>>> side and one for the last few turns where the others are afflicted
>>>> with "Decca scrunch".
>> I gave a talk on this subject at the ARSC conference in Nashville in 1997.
>> Two perfectly synchronized copies would provide a theoretical signal-
>> improvement of 3 dB, four copies an improvement of 6 dB and eight copies
>> improvement of 9 dB. The first problem is finding so many copies in E
>> But the bigger problem is how to achieve perfect synchronization.
>> John S Allen of the Boston Audio Society discusses this matter in an
> article he
>> wrote for the Spring 1990 issue of the ARSC Journal. He says the accuracy
>> sync must be "about ten microseconds (72 degrees of phase shift at 20
>> No real-world turntable is stable enough to achieve this result on
>> plays, and I proposed a stack of tables all powered by a single motor for
> playing the
>> discs simultaneously, with use of digital delay lines to align the audio
> from them
>> after transferring.
>> Discs which are even slightly out-of-round would need to be matched
>> with others of the same shape (not impossible, since these discs reflect
> the shape
>> of the metal stamper used to press them), and digital "azimuth correcting"
>> might be used to help deal with alignment variables such as this.
>> Doug Pomeroy
>> Audio Restoration & Mastering Services
>> Transfers of metal parts, lacquers,
>> shellac and vinyl discs & tapes.
>> 193 Baltic St
>> Brooklyn, NY 11201-6173
>> (718) 855-2650
>> [log in to unmask]