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From: gregr@tekig1.UUCP
Newsgroups: net.audio
Subject: Re: How my ears are built  (and a question) A reply
Message-ID: <1192@tekig1.UUCP>
Date: Wed, 6-Jul-83 19:10:36 EDT
Article-I.D.: tekig1.1192
Posted: Wed Jul  6 19:10:36 1983
Date-Received: Fri, 8-Jul-83 09:46:48 EDT
References: <1211@tektronix.UUCP>, <618@hou5e.UUCP>
Lines: 51

You asked why various high end preamps sound different when auditioning
them with a phono cartridge at an audio solon...?

The answer to this question has been explained very well over the years
in audio publications (Audio, others).  The major difference is in the
way the preamp loads the cartridge.  Preamps have widely varying input
capacitances which moving magnet cartridges are very sensitive to. 
(Other complex loading problems also exist and RIAA equalization errors
are possible but these are second order effects in well designed and
usually expensive preamps.)  It is ABSOLUTELY necessary to adjust the
input C for each preamp tested to be the same as all others being tested.
Since most preamps allow no adjustment or only very coarse adjustments
(100 pf steps or so) this must be done with add-on capacitors either
internally (best) or externally (rather poor).  Different cartridges have
different sensitivities to C variations.  (I suspect this explains the
tendency for subjective reviewers to proclaim that one cartridge is better
than another because it allows differences between preamps to be heard.
In fact there probably is no correlation between C sensitivity and sound
quality.)  Notice that we are comparing preamps here and adjusting for
equal C for each preamp with ONE cartridge.

If the object is to compare cartridges we should use ONE preamp but
adjust it for different C values for each cartridge tested.  Again this
is ABSOLUTELY necessary because each cartridge produces its optimal
performance with a particular capacitive load.  (This easily explains
why certain cartridge-preamp combinations sound better than others.)
Also note another related problem due to capacitance.  If tonearms
(or integrated tonearm-turntable combinations) are to be compared they
will have widely varying cable capacitances depending on length and
cable type.
Therefore to compare tonearms the capacitances must be made equal,
but to compare cartridge-tonearm combinations the C values should be
optimized for the particular cartridge used.

If you think this sounds like a lot of effort to compare differences in
the way components sound --- your right!  Accurate comparisons between
components is virtually impossible in a store regardless of how friendly
the salesman is.  Notice that I'm not even talking about scientific
testing i.e. double-blind controlled statistical testing. Even if you are
a "golden eared audiophile with perfect sensory memory and nothing to
prove" you still can't make valid tests when you overlook (re don't
understand) how components work and their sensitivities.

Oh yes, do cartridges and speakers sound differently?  Of course, they
are electromechanical with widely varying designs and measureable
performance differences.  Do preamps sound differently?  After very
time consuming, controlled testing I believe so.  But very subtle
differencs when testing problems like above are corrected.  The
problems, defects, and variations of the electromechanical elements will
mask virtually all of these differences when the preamp setup is
correct.  Equalizers however are a completely different story .....