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From: EBERGER@B.PSC.EDU
Newsgroups: rec.audio.high-end
Subject: Re: Listening To More Polystyrene Capacitors
Message-ID: <900410111221.21004182@B.PSC.EDU>
Date: 10 Apr 90 21:19:53 GMT
Sender: news@uwm.edu
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Approved: tjk@csd4.csd.uwm.edu


The circuit I use for evaluating these capacitors ~750pf & ~3000pf is a 
simple NE531 ic-opamp based phono preamp with regulated powersupply.

This circuit uses an active RIAA eq very similar to the Audio Research SP-6
series preamplifiers.  The circuit is built with 1% resista resistors and 
WonderCap power supply bypasses.  It uses an electrolytic (yuck!) in the 
feedback path to ground so that it can be direct coupled to the line in of
a modified SP-6 (exhaustive parts changes, India 12AX7s).  Speakers/Amps 
are modified Acoustat X electrostatics/servo-charge amps on stands.

Input source is a Supex SDX-1000 mc (modified& still running after 8yrs!)
pre-preamplified by a Thorens PPA-990 headamp (modified).

Cables are all Livewire DB-1 litz interconnect, which aren't made anymore,
but really should be, since they ARE my favorites :-)

Most of the products are very picky about ancillary components, so chances
are that nobody except for me and few friends will appreciat them, especially
the Dual 731q direct drive turntable (Anyone have one for sale?)

The SP-6 already has SIEMENS caps in the RIAA stage, so I made the test setup
to try other things like different ICs & eq caps.  I like the NE531 IC for its
dynamics & bass, but it is a quirky chip, and was used by Rappaport as
digging into a dead lump of epoxy & wires revealed...

-Ed Berger
eberger@b.psc.edu