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

[Eric Jacobs <EricJ@xxxxxxxxxxxxxxxxxxx>]

I did have a discussion with Stan Ricker before even posting to the
list, and Stan fell on the side of there being much bigger problems
than the Neumann time constant when looking at the total phono
recording and reproduction chain.  This sentiment has been echoed by
most of the respondees to this thread.

I did like Bob Olhsson's comment that "Virtually everybody I know
adjusted their Neumann cutting systems to be flat to the RCA test
records that were the basis of the RIAA curve."

Which leads me to the questions:

1.  How accurate are the test records (+/- how many dB)?
2.  How flat were the cutting systems (+/- how many dB)?

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.

So the first question to ask is just how accurate does RIAA
playback need to be with respect to the source material (ie. the
disc cutting system).

Just trying to look at phono reproduction both scientifically and
practically.

Eric Jacobs

The Audio Archive
tel: 408.221.2128
fax: 408.549.9867
mailto:EricJ@xxxxxxxxxxxxxxxxxxx



-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of Tom Fine
Sent: Friday, March 30, 2007 3:26 PM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] RIAA phono EQ and Neumann time constant


Hi Eric, Graham, etc:

I think this is a tempest in a teapot. I have many an LP cut on Neumann
lathes and they do not sound
the least bit dull. If you want some science applied (as opposed to an LP
fan's ears), contact
someone like Stan Ricker and ask him. I doubt there is a real problem here.

-- Tom Fine