[PStamler]

On Apr 11, 11:40*am, (Adrian
Tuddenham) wrote:
Scott Dorsey wrote:
Adrian Tuddenham wrote:

That's interesting. *We don't get many Red Seals this side of the pond,
but it would be helpful if you could let me know the turnover
frequencies (or time constants). *There have been several attempts to
draw up definitive tables of turnovers for different makes at different
times, but they always seem to be incomplete, in dispute or inaccurate..

It's a two pole filter. *F1 is specified at 500 Hz, F2 is 1590 Hz and
set for 13dB at 10 Khz. *Maybe.

Even wackier is the Columbia stuff! *Columbia used a three-pole filter
like the modern RIAA curve on some of their later 78 and early LP pressings.
F1 at 100 Hz, F2 and 500 Hz, F3 at 1590 Hz, and something like 16dB boost
at 10 Khz.

None of these numbers are guaranteed, and the might be totally wrong. *But
they aren't any worse than the ones in the McIntosh preamp book.

Thanks for that. *Now you have reminded me, I'm think I remember reading
something about those turnovers some years ago. *My recollection is that
they didn't apply to pre-WWII recordings, so there was no need to
remember them.

In North America they did, from early days of electrical recording.
And every label was different.

Record dealer Kurt Nauck has compiled what is probably the most
accurate directory of 78 EQs. It's certainly the most exhaustive.

All that said, one still needs to use one's ears. Despite the
"official" numbers, I find that (for example) turnover frequencies of
50Hz, 500Hz and 3180Hz sound excellent on many electrical US
Columbias. The extra octave of bass boost and the extra extension of
treble response may be compensating for losses in the system --
whatever, they sound good to my ears.

The recommended curves make a good starting point, but you still need
to use your ears and judgment.

Peace,
Paul