From: Patent Tactics, George Brock-Nannestad Richard Hess wrote and shortened Eric Jacobs' mail: Hello, just a short input: 1) the actual modulation on the records, during mastering and from the finished record, is usually measured by the light-bandwidth (actually the width of the band of light) method originally according to Buchmann-Meyer (introduced into the US by Ben Bauer). That entirely bypasses the tracing loss and other losses in the stylus-groove interface. So, you may be certain that the test records are very close tolerance, but you must use an ELP in order to get the benefit. 2) I believe that the delay (phase) problem of having a mismatch between pre- and de-emphasis will be the predominant issue. 3) I worked my way through the various more or less official discussions on pre-and de-emphasis for a paper I gave at AES: "Pre- and De-Emphasis - A Forgotten Necessity", AES Convention Paper No. 5360, 110th Convention 2001 May 12-15, Amsterdam. The sad conclusion (in a discussion of standardization) was that after the advent of the tone control, all standardization of this nature lost its relevance. Kind regards, George > At 03:25 PM 2007-04-01, Eric Jacobs wrote: > >Having a good understanding of the minimum error in the disc cutting > >system (ie. just how flat a frequency response could be achieved, and > >how accurate are the test discs used to calibrate the cutting systems) > >will help make specifying minimum RIAA accuracy for reproduction less > >arbitrary. If disc cutting systems were accurate to 0.1 dB of RIAA > >from 20 to 20 kHz when properly set up, then I think the Neumann > >constant is worth looking into more deeply. If disc cutting systems > >were accurate to 1 dB of RIAA, then the Neumann time constant is a far > >smaller consideration. > > > >I do believe it is a slippery slope to say that just because there are > >many other elements in the reproduction chain that introduce far > >bigger errors, we should ignore the potential influence of the Neumann > >time constant - especially if the Neumann time constant could be easily > >compensated for. > > Hello, Eric, > > I believe that we will be very lucky to be holding +/- 1dB from 20 to > 20 kHz with the tape component--in fact, holding +/- 1 dB from 50 to > 15 kHz across the board would have been quite excellent. In just ten > tapes from a major broadcaster known for their quality, I saw one > tape way outside +/- 1 dB at 15 kHz and each session varied within > the range while tapes from the same session were very close. These > were 15 in/s tapes. > > While that begs the issue of direct-to-disc recordings, I would > suggest that the vast majority of recordings made from perhaps 1950 > until the end of the LP era were made via tape. > > Yes, it's a slippery slope and that's why I suggested that you > contribute an article about this to my blog where we can document all > of these little gotchas. It doesn't have to be long, but I will set > up a separate topic as I plan to add more tape ones in the future -- > or if you write it on your own website, I'll make a note of it and link to > it. > > And oh, the chemistry issues. Tapes, like the plumbing in "The Money > Pit", are not getting better with age. > > Cheers, > > Richard >