Bias And Equalization - Nakamichi 500 Operating Instructions Manual

Bias and Equalization
Position of ' | Position of
Bias Switch
Eq. Switch
Nakamichi
TDK
Sx: ba Maxell
Ex
normal
Nakamichi
Nakamichi
Fuji
EX @ 120 & Maxell
Maxell
TDK
ex 70
normal 120
NORMAL
Shown above are the recommended
cassette tapes and the proper bias and
equalization settings for each (tapes other
than Nakamichi are listed in alphabetical
order).
Type or Mode!
SX
SA
UDXL-H
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
C-60, C-90
Bias Switch
Bias is an inaudible high frequency signal
applied to the tape during the recording
process. It reduces distortions and
non-linearities inherent in magnetic
recording. For many years there was
basically one type of tape so that only
engineers needed to concern themselves
with bias. Today there are a multitude of
tape formulations, and almost as many
differing biasing requirements. Nakamichi
EX tape and other low-noise/high-output/
high-density type tapes require some 10%
greater bias than normal ferric oxide tapes
for optimum results. High-coercivity
tapes, such as Nakamichi SX, require
approximately 45% greater bias. The
three-position bias switch on the Nakamichi
500, therefore, allows the selection of the
proper bias for the various types of
cassette tapes.
Equalization Switch
Equalization (EQ) is the method by which
optimum signal-to-noise ratios and
frequency responses are obtained for the
various tape formulations. Like bias, the
proper EQ must be selected for each kind
of cassette tape. Unlike bias, EQ concerns
not only the recording process but the
playback process as well. The EQ switch,
therefore, must be properly set for both
playback and record.
There are two equalization 'curves' now
recognized as standards throughout the
cassette industry. All conventional ferric
oxide tapes and the newer low-noise/
high-output formulations (including
Nakamichi EX and EX If) utilize the 120
microsecond equalization time constant.
High-coercivity tapes, such as Nakamichi
SX, utilize the more recently established
70 microsecond time constant. Select the
proper time constant with the EQ switch
for record and playback by referring to
the table of recommended cassette tapes.