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Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.audio
Subject: Re: Medium priced cassette decks
Message-ID: <2215@watcgl.UUCP>
Date: Fri, 9-Mar-84 00:58:00 EST
Article-I.D.: watcgl.2215
Posted: Fri Mar  9 00:58:00 1984
Date-Received: Fri, 9-Mar-84 06:51:46 EST
References: <6063@decwrl.UUCP>
Organization: U of Waterloo, Ontario
Lines: 26

I have a Harman-Kardon HK200XM tape deck; it has bias adjust and Dolby HX.
I regard bias adjust as a feature useful only in emergencies.  To properly
adjust a deck for a particular tape requires setting bias, equalization,
and record level.  Front-panel bias adjust lets you match the bias to
the tape by ear, but you can't get the others right so you won't get
the highest quality results.  For ordinary use, pick a tape, get you
deck adjusted for it, and then use nothing else (actually you can pick
1 metal tape, 1 chrome, and 1 normal).  Dolby HX:  Well, I THINK I can
hear a more open high end with it switched on, but I might just be fooling
myself.  HX works by reducing the bias level when the recorded signal level
is high, allowing higher levels to be recorded without saturation.  But
this changes the frequency response, requiring a variable equalizer whose
equalization changes track the bias level changes.  It does have two bad
side effects:  On music with transients which are considerably above the
level of the background, I think I can hear funny things added to the
sound as the equalizer comes in and out - nothing I can hear directly, but
it doesn't sound quite like the original.  And on high input levels, the
bias level is reduced to the point where the erase head isn't completely
erasing the old material.  If you bulk-erase you cassettes before recording
on them (a good idea) this doesn't matter, but watch out for it!

Basically, it's a good idea (higher overload levels, lower distortion at
low levels since the bias current is increased above "normal") that
may have flaws in implementation.  Make a recording with a highly-dynamic
piece of music on a sample deck with HX in and out, and listen for yourself.
My deck's "funny noises" may not be typical.