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[Gold]

I asked the guru. He couldn't think of any way the circuit breaker influences the stylus motion other than killing the signal when tripped. I could get a copy of the SAB74 schematic if you want to take a look at it. I took another look at the SI66 breaker schematic and there is no servo/feedback path.

[mcsnare]

Bruno, maybe you could design a post cutter head feedback servo that would reduce cutter head distortion. Probably require a re-design of the cutter itself. Some kind of strain gauge accelerometer? Then again those shiny black discs might not sound as cool.

Dave

[bruno putzeys]

You mean more "post" than the sense coils? I could quite easily design a servo with a lot more loop gain than the usual ones, but beyond that I think that the difference in shape between the playback and cutting styli will become the more fundamental problem.

Actually I tried starting such a project but I was held up by other stuff. By the time I was ready to characterise and model the loaner cutting head the owner needed it back (on account of having fried another one). I should pick it up again.

[Gold]

Yes, the problems are all on the playback side. If Bruno could design a playback stylus with a 1 micron tip radius that wouldn't break, most of the distortion would disappear.

[bruno putzeys]

I think breaking would be problem #2. A tougher issue would seem to me wearing out the record too quickly with all tracking force concentrated on such a small area. It's a pity the idea of predistorting the cut to correct for playback distortion never got universally adopted.

[Geoff Emerick de Fake]

Bruno Putzeys wrote on Tue, 12 January 2010 11:53

It's a pity the idea of predistorting the cut to correct for playback distortion never got universally adopted.

I think the reason was that it never worked practically. Same with predistorting the record signal on some tape machines; on the 3M machines, it was always turned off. It needed the machine to be super-aligned and would need re-adjusting from one reel to another (some times from the beginning to the end of the reel).

[dietrich]

Anyone familiar with the Sax Mastering lab tube cutting amps? did the use on a neumann or scully?
D

[TotalSonic]

dietrich wrote on Fri, 05 February 2010 15:29

Anyone familiar with the Sax Mastering lab tube cutting amps? did the use on a neumann or scully? D

Dietrich -
Doing a Google search seemed they had two Scully's and a Neumann.  I haven't been able to find much more details than that yet.

Best regards,
Steve Berson

[dcollins]

dietrich wrote on Fri, 05 February 2010 12:29

Anyone familiar with the Sax Mastering lab tube cutting amps? did the use on a neumann or scully? D

It was Scully with Neumann cutterheads.  Driven by custom tube amps designed by Sherwood "Bert" Sax.

DC

[Jerry Tubb]

dcollins wrote on Fri, 05 February 2010 17:39

dietrich wrote on Fri, 05 February 2010 12:29 Anyone familiar with the Sax Mastering lab tube cutting amps? did the use on a neumann or scully? D It was Scully with Neumann cutterheads.  Driven by custom tube amps designed by Sherwood "Bert" Sax. DC

Anyone ever copied Doug Sax's fabulous sounding tube mastering path?

or is it a well guarded secret? (perhaps the Pendulum gear?)

curious - JT