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Re: [ARSCLIST] RIAA phono EQ and Neumann time constant

From: Patent Tactics, George Brock-Nannestad

I am with Graham on this: the temperature of your vinyl record and of the 
rubber bearing of your cantilever will have more of an influence. 

Kind regards,


> Eric Jacobs wrote:
> > I've been thinking about the RIAA phono EQ curve, and realized that
> > the majority of discs in Europe and many in the USA are cut on 
> > Neumann lathes.
> Don't think Eric... it is bad for you!
> I think (there goes that thinking again!) Stephen Temmer  and Georg Neumann
> would roll over in their graves to hear some of this.
> The cutter life problem was caused by the record characteristic pre-emphasis
> overdriving the cutter heads on things like cymbal crashes and other loud
> high 
> frequency stuff.  This would burn out the cutter drive coil necessitating a
> VERY expensive repair on the cutting head.  There was a fuse supposedly to
> protect the head coil but the coil always protected the fuse!
> Neumann and others developed high frequency limiters on their cutter drive
> amplifiers to prevent this from happening.
> I have a hard time with Neumann doing something non-standard, particularly
> when 
> the above method appeared to work successfully.
> > If your average phono preamp is -0.5 dB at 20 kHz, that means that you 
> > could be off by as much as -1 dB or more.
> And I suspect that people, even in an A-B comparison test, CANNOT hear that
> difference.
> > I know there are many more things to think about, like the accuracy 
> > of the cartridge frequency response, the cartridge loading, the vinyl
> > wall stiffness, etc. and that the sum of potential errors in phono 
> > reproduction is fairly inaccurate to begin with.
> Errors big enough to drive a truck through.
> > There's also the bigger unknown of whether the cutting lathe was 
> > in or out of spec.
> And in most cases, you would find the cutting system chain would not be 
> precisely in spec on all it's components... but most were close enough that
> nobody doing a listening test could tell.  What about cumulative opposite 
> errors in the chain where one effectively cancels the other?  The mind 
> boggles... I'm going for an aspirin.
> > I also know that most discs cut in Europe since the late 1960s were
> > cut on Neumann lathes, but figuring out what was cut on Neumann lathes
> > in the USA is more difficult - perhaps half of all lathes in the USA
> > are Neumanns. [visually, you can identify a disc cut on a Scully 
> > automatic lathe, but that's about it]
> The evidence of the cutting lathe type can be seen in the run out where it
> forms a lock groove... and it only signifies the mechanical lathe that the
> cutting head was mounted on.
> At RCA Victor in our stereo mastering suite, we had a Neumann lathe, with a
> Westrex 3D cutting head, driven by Haeco amplifiers from an Ampex tape deck
> equipped with a variable pitch/depth preview head.  We had RCA audio
> amplifiers 
> driving LC-1A monitors and we managed to output a lot of award winning 
> recordings with no concerns about being down 1 dB at 20 kHz!
> > What do people on this list think about this Neumann lathe time constant
> > and it's influence on RIAA playback accuracy?  Is it important, or not?
> If any people are really worrying about this, I suggest you get back on your
> meds.  The number of grains of sugar in that spoonful you put in your
> morning 
> coffee is more important!
> ... Graham Newton
> -- 
> Audio Restoration by Graham Newton, http://www.audio-restoration.com
> World class professional services applied to tape or phonograph records
> for
> consumers and re-releases, featuring CEDAR's CAMBRIDGE processes.

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