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

[Tom Fine <tflists@xxxxxxxxxxxxxxxxxxx>]

Here's the biggest gotcha of all with LPs -- and why in some cases, the original LP sounds better 
than any subsequent reissues. In many cases, mastering engineers would make on the spot decisions, 
based on how their hearing was that day, how the tape deck was adjusted, how the lathe was behaving, 
etc. Some mastering engineers made very careful notes on the tape box (Pultec attenuated 5dB at 
2500hz, or the like, for instance), many didn't.  So then the CD era comes along, or the archiving 
era. The engineer taking that tape and making a commercial CD master might go very carefully between 
the original issue and the tape and figure out what the LP cutter did, he might not because he might 
decide he has a better way to skin the cat. Or he might just transfer the tape as close to how it 
plays back as possible (what I call "forensic mastering" -- which is ideal in an ideal world but few 
music master tapes are perfect or couldn't use the last bit of special sauce in the release-media 
mastering). The net-net is that there are TONS of variables and very few tapes or LPs made outside 
of research labs or alignment-media companies are "perfect".

For the purposes of digital archiving, a "forensic transfer" is probably best, aligning azimuth to 
the source tape and setting EQ with the tones that are hopefully on the source tape (more likely 
with something coming out of a professional studio or broadcast facility, less likely with home or 
semi-pro recordings). As for archiving grooved disks, I think it's most important to invest in as 
undamaged source disks as possible and in a top-drawer cleaning machine. Beyond that, using a preamp 
that is close as possible to the desired curve will get you there within reasonable tolerances. As 
with all other media archiving and transferring, research and "pedigree information" is the most 
valuable resource most likely to lead to a good archival copy of something.

-- Tom Fine

----- Original Message ----- 
From: "Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Sunday, April 01, 2007 4:17 PM
Subject: Re: [ARSCLIST] RIAA phono EQ and Neumann time constant


> 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.