From: utzoo!watmath!watcgl!dmmartindale
Newsgroups: net.records
Title: adjusting cassette decks to match the tape
Article-I.D.: watcgl.89
Posted: Sat Jan  1 14:47:50 1983
Received: Sun Jan  2 00:07:23 1983

(this discussion probably belongs in net.audio, but since it started
here I'll continue.)
Hmm.  I just assumed that the decks which didn't have the fancy auto-biasing
circuitry would have the usual large collection of trimpots.  Any deck which
doesn't have a sufficient set of calibration controls probably shouldn't
be part of a "hi-fi" system since you simply can't expect good results
from it.  This would certainly be something to check on when buying a
deck, although I would be very surprised if any deck which had decent
frequency response lacked the adjustments.
For an idea of what to expect, my deck (Harman/Kardon hk200XM) has
the following internal tape-specific adjustments:

	record level, record equalization for each channel for each of 4
	   tape types - total 16 potentiometers, plus two adjustable
	   inductors.
	record bias level for each of 4 tape types - 3 pots and two
	   trimmer capacitors.

All of the above may need changing if you changed all 4 types of tape
your record on; switching one of the four would probably only require
changing 5 adjustments.  There are also the following adjustments which
don't depend on the tape used, but must be set properly nonetheless
(and may need occasional readjustment):

	head azimuth
	motor speed
	playback level calibration (two pots)
	playback equalization (two pots)
	bias trap (two inductors)
	Dolby HX threshold (4 pots)
	level meter calibration (4 pots)

Now, most decks won't have the Dolby HX adjustment, but better decks may
have a pair of additional playback EQ adjustments or Dolby B or C threshold
adjustments.
My deck does have a front-panel bias trim adjustment, but I consider it
useful in emergencies only because there is no corresponding record
equalization adjustment.

You can see that an analogue tape deck has a LOT of adjustments that affect
its performance, and the only way to get what it's capable of is to get them
set properly in the first place, and check them once in a while.