Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!philabs!cmcl2!floyd!whuxlb!pyuxll!eisx!npoiv!npois!hogpc!houxm!whuxk!wjm
From: wjm@whuxk.UUCP
Newsgroups: net.audio
Subject: hearing.high.treble
Message-ID: <227@whuxk.UUCP>
Date: Thu, 30-Jun-83 13:34:36 EDT
Article-I.D.: whuxk.227
Posted: Thu Jun 30 13:34:36 1983
Date-Received: Fri, 1-Jul-83 12:37:05 EDT
Lines: 45

While the "nominal" high end of human hearing is 20KHz, this is only one of
those biology or med school textbook "normal" things.  There are some individuals
in the population (most of whom are < 40 years of age and who havn't abused their
ears by working in high dB environments or listened to disco music at disco
volume levels) who can perceive sounds at or above 20 KHz.  I personally am
blessed and/or cursed with this situation - blessed since I can enjoy the high
end on my stereo system and the top octave of music - e.g. the bells in the 
'1812 Overture' and harp music - but cursed since ultrasonic anti-shoplifting
alarms operating at 25KHz drive me to the Excederin or Tylenol bottles!
Therefore, I contend that flat response to 20KHz should be a design objective
of high fidelity audio equipment.   Admittedly, when one is designing to a
more moderate price, one may have to compromise here (as in many places) but
one should not design a digital system, for example, with a sampling rate of
less than 40 KHz (the minimum rate needed to reconstruct a 20KHz signal from
sampling theory).

Also to re-open an ongoing controversy, this is the reason that I stand by
my contention that the Shure V15 Type V is not a top of the line cartridge
and why I would pay 2x the $$ to purchase certain other MC cartridges.
According to the lab test reports in last summer's issues of "Stereo Review"
and "High Fidelity" (I'll provide page and specific issues on request, if
anyone can't find them) the V15-V has two serious flaws in the top octave.
1.  Its frequency response is rather non-flat around 16KHz
2.  Its stereo separation is < 10 dB at 20KHz.  Given that the high frequencies
    are the most directional, I regard this as a significant problem.
Don't get me wrong - the V15-V is a fine cartridge for its $125 price, and I've
recommended it to some of my friends for use in a $1K to $1.5K system.
However, lets not kid ourselves, it isn't in the same class as the following
$250-300 MC units - the Adcom XC-LT (my present cartridge), the Dynavector
23R, or the Denon 103D (two units I'm considering to replace the Adcom which
is showing its age - another Adcom is also on the list)
I'm not necessarily partial to a particular transducer technology.  Like mayny
engineers, all I care about is the quality of reproduction.  However, the only
cartridges that I've heard so far (when price is no object, of course) that
challenge the state of the art are MC's.  If someone can design a MM that falls
in this class, and that is verified by independent lab tests, I'll be the
first to acknowledge it - and be happy not to use a head amp.
but until then I'll just have to stick to MC's.

End of flame ....                                Bill Mitchell
                                                 Bell Laboratories - Whippany 
                                                 (whuxk!wjm)

Disclaimer ... of course, all opinions submitted by yours truly to this
newsgroup are my personal opinions and not those of Bell Laboratories.