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

["Steven Smolian" <smolians@xxxxxxxxx>]

These are solutions if the tape is absolutely physically flat.

In the real world, however, many tapes are scatter wound.  When played back,
one portion of the tape is in contact wth the gap before the others.  The
relationship is continually reversed as the tape twists by.

Some tape can be flattened by slow winding and medium time (3-6 mo) storage.
After the requisite passage of time, it is often necessary to wind it to the
other end and go through another waiting period.  This method works
sometimes, works partially more frequently, and only partially if at all on
.05 mil untensilized tape,of which there is a surprising amount out there.

It is always worth trying provided the producer is willing to postpone
production while flattening is going on, which is almost never.

Hence my suggestion about dividing the tracks and trying to synchronize the
mono signals.  Is the phase slewing more noticable than the extra hiss?  How
successfully can the hiss be dealt with in subsequent processing?

As is often the case in sound restoration, this is a judgement call made in
the studio.

Steve Smolian




=========================
Steven Smolian    301-694-5134
Smolian Sound Studios
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----- Original Message -----
From: "Don Cox" <doncox@xxxxxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Friday, December 27, 2002 6:51 AM
Subject: Re: arsclist Transfer of multiple copies, was: Full 3-D mapping of
groove?


> On 26/12/02, Steven Smolian wrote:
> > If you are working from a full track mono and are willing to give up a
> > bit of signal to noise, you could use a two-track stereo head. This
> > assumes the gap is wide enough to allow independent reading of the
> > separated sections with sufficient data to effect the appropriate
> > adjustment..
>
> Sure, but this is just the simplification of the problem. Every track on
> a multitrack tape with an azimuth discrepancy will have the same
> problem.
>
> Typically, you get a comb filter with the first notch somewhere above
> the audio range, so that it appears as a top cut. So to restore from
> that, you would need a circuit or algorithm with a frequency-dependent
> phase shift.
>
> As you say, using a narrower head will reduce the effect, but it
> increases the noise, so this is not a good approach.
>
> Regards
> --
> Don Cox
> doncox@xxxxxxxxxxxxxx
>
> -
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