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

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

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


Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.