Re: [ARSCLIST] RIAA EQ software

[Tom Fine <tflists@xxxxxxxxxxxxxxxxxxx>]

The RCA record was present at every studio I know of that had cutting facilities. Here's where my 
point about playback and the real world comes in. The RCA record is incredibly useful with a 
listening system, if you assume the cutting engineer tried to "encode" the curve. You'll find that 
most phono preamps need a tweak here or there to flatten the curve, much as using an MRL tape to 
align a tape playback requires a tweak here or there of the EQ trimmers if you've changed heads or 
components have drifted in the playback amp. My parents' system had a VU meter between the Marantz 
preamp and the power amps and my father would use the RCA record and the tone controls to flatten as 
much as possible the RIAA playback (with any decent cartridge designed for the loading of that 
preamp, he could get it +/- less than a dB). The Maranz had separate bass and treble controls for 
each channel, which was handy.

Look at old stereo gear specs for the phono preamp, you'll see that acceptable tolerance was 
+/-1-2dB in many cases. I think that's fine for listening in the home but may not be precise enough 
for some archival purposes. However, it's non-ideal in the first place to have only a pressed RIAA 
LP of something to transfer. Much better to expend the efforts and find and transfer the master 
tape.

As for pleasure listening, I betcha some of the most euphonic phono preamps aren't "troubled" by 
being 2 or more dB out of the curve at various points.

-- Tom Fine

----- Original Message ----- 
From: "George Brock-Nannestad" <pattac@xxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Tuesday, August 26, 2008 5:51 PM
Subject: Re: [ARSCLIST] RIAA EQ software


> From: Patent Tactics, George Brock-Nannestad
>
> Bob, you wrote:
>
> > -----Original Message-----
> > From Eric Jacobs: "Weren't all those math formulas and standards the basis
> > of the RCA test record?"
> >
> > In terms of public dissemination, the test record predates all of them
> > that
> > I'm aware of although no doubt there was some sort of internal
> > documentation
> > at RCA.
> >
> > The 1953 standard specified a series of 23 frequencies ranging from 30 to
> > 15k. as is found on the test record. This was only later described as the
> > 3180, 318 and 75 microsecond time constants so the RCA test record may
> > well
> > have been the basis and not the other way around.
>
> ----- well, on the cover of my 10" record, next to the equivalent LR, and 2x
> RC networks are given the time constants you mention. The text reads:
>
> "The 'New Orthophonic' characteristic (relative stylus velocity vs.
> frequency) may be expressed as the algebraic sum of the ordinates of three
> individual curves which conform to the admittances of the following networks
> expressed in dB".
>
>
> My record is not dated, and I would be interested to know the date.
>
> Again it should be the
> > basis of any attempt at accurate reproduction simply because it was what
> > everybody trimmed the response of their cutting systems to match. How
> > right
> > or wrong the RCA test record is doesn't matter.
>
> ----- you are absolutely right and in accordance with the instructions on the
> record. If this record was widely distributed, obviously that WAS the
> standard.
>
> Kind regards,
>
>
> George