Re: arsclist ELP Laser Turntable; Full 3-D mapping of groove?

["Steve Smolian" <smolians@xxxxxxxxx>]

I gave a brief paper, I think at the Audio Engineering Society c. 1989
suggesting the mapping idea.

It related to wax cylinders rather than discs.  They need help even more
badly.

The technology to play back sound from a digital picture of a groove
introduces an extra layer of R&D complexity.

It seems far simpler to me that, after repairing the groove image in the
computer, that a lacquer disc be cut from the groove image just as car
models are sculpted from 3d images created in the computer.

The groove can be lateral and can play back on any decent record player.

The technology to do this with sufficient accuracy will have arrived when
dental appliances are made this way.  I keep tabs on the state of this art
as part of my 6 month checkup.

Has the time for this inevitable advance finally arrived?

Steve Smolian

----- Original Message -----
From: "Jon Noring" <jon@xxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Wednesday, December 04, 2002 7:21 PM
Subject: arsclist ELP Laser Turntable; Full 3-D mapping of groove?


> George Brock-Nannestad wrote:
>
> >Now, if the signal were cleaner from
> >the outset, such as from the ELP Laser Turntable (which has no
> >inertial parts), then there would be no need for this sophistication.
> >So, it is really a question where you want to put your money: in
> >hardware for the ELP or in software for the CEDAR.
>
> I've always been intrigued with using a laser for transfering 78's
> because of the inertial interaction between the groove and the
> stylus, which as George noted becomes a problem when the stylus
> encounters groove damage, abrasive particles in the shellac, dirt,
> etc., etc.
>
> So I found George's comments extremely interesting.
>
> I just went to ELP's web site and it is definitely an interesting
> piece of hardware. So the obvious question is how well does model
> LT-1XA perform in playing 78s? Can it handle slightly warped or off
> center disks? What are the other "real world" problems with it for
> transfering 78s?
>
> On another note, having worked as an engineer at three DOE National
> Labs, and alongside several scientists who did laser doppler
> velocimetry and similar laser techniques, I've always been intrigued
> with the obvious next step: to use laser techniques to accurately map,
> in three dimensions, the groove of a shellac disk. Once mapped, it is
> conceivable to then "play it back" in a computer and reproduce the
> wave form. The advantage of this is that all the spatial information
> of the groove becomes known, and it may be possible to compensate for
> various types of groove damage, abrasive particles sticking out in the
> shellac, record warpage, etc., etc. -- in essence to be able to
> reconstruct the groove near to its original pristine form as originally
> mastered.
>
> The fundamental problem with running a stylus through a groove is that
> all this intricate 3-D detail is lost -- the stylus integrates these
> three dimensions essentially down to one, and adds insult to injury by
> adding artifacts of its own to the signal! It is a massive loss of
> very useful information.
>
> Obviously, a groove mapping technique would be an expensive proposition
> to research and develop, and probably to even operate (has somebody
> already tried this?), so it may have limited use, maybe for extremely
> rare and noteworthy recordings where a master pressing or a shellac
> pressing in E condition or better is not available. There's quite a
> few researchers at the National Labs with the requisite backgrounds
> who would find this to be a real interesting problem and may consider
> exploring it on their own time with minimal or no funding, at least to
> research the feasibility of it for writing a cogent proposal. There is
> a lot of interesting technologies which have been developed at the
> National Labs over the years.
>
> Comments? Criticisms?
>
> Jon
>
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>


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