In article , Serge Auckland
wrote:


My two turntables both had 741s in the RIAA equaliser, which I replaced
with TL071s, only because I couldn't stand the idea of 741s. The TL071
is a direct plug-in replacement and the equalisers have their ICs on
sockets, so the replacement was easy. I didn't even have to solder
anything. I suppose the distortion of the TL071-equipped equaliser could
be lower than before (I didn't measure a before and after) but any
reduction would be swamped by the inherent distortion of vinyl and the
cartridge. I certainly haven't noticed any improvement, I just feel
better not having 741s in the signal path.

When I used to do such things I ended up designing a pre-amp using
HA12017's for all the gain stages. This despite the IC being intended by
Hitachi as an RIAA preamp for MM cartridge. I couldn't hear any real
differences between this and other ICs I tried - nor could anyone else I
tried the comparisons on at the time. However the HA12017 gave slightly
better results in terms of various specs, so coped with a wider range of
signals and output loads.

Took a little fiddling with the compensation to make it work, but turned
out OK. So far as I know, no-one else used the HA12017's like this, and I
guess they are long obsolete nowdays! :-)

FWIW When I tried using stabliser ICs like the 78/9XX familiy I also found
they tended to oscillate at a few MHz, so built PSU regulators with
discrete devices. So far as I recall, there were no audible effects I or
others noticed due to the oscillations. I had RF decoupled the power lines
on each individual IC, though. Just seemed a good idea to make a better
PSU.

Oh... and I don't really have a 'Desert Island Discs' list as I keep
changing my mind about what I am enjoying. Most recent has been the Rubbra
Symphonies (Hickock BBCNoW on Chandos) but before that it was a collection
of Benny Goodman Sextet on a Vocalion/Dutton CD. Before that I think it was
a recording of some Alain organ music from R3 performed by his sister in
1981 and 1986. Before that Pentangle... Special favourites from a while ago
include the Uchida sets of Schubert and Mozart sonatas, and some of the
re-issues of Duke Ellington with extra tracks.

Slainte,

Jim

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