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6 . P L A Y B A C K E O U A L I Z E R A D J U S T M E N T
Information
Theoretically, the output voltage increases
6dB/oct in proportion to the frequency.
Practically, it decreases in the hish frequency
range.
Fig. 7 shows the relation between frequency and
response.
Losses in response
a. Eddy-current loss: This is caused by Eddy-
current which flows in head core. Eddy_current
loss is proportionate to the frequency.
b. Spacing loss: This is caused by a space between
surface of head and that of tape coating.
This loss is also proportionate to the frequency.
c. Gap loss: This loss is attributable to a gap of
the playback head, and is maximized when
the length of the head is equal to the wave-
length of the recorded signal.
Playback equalizer compensates these losses.
P . B a c k e q u a l i z e r c u r v e
Theoretical
Actual curve
Fig. 7
G T - F 9 1 9 1
Adjustment
a. Connect an AC voltmeter to the output termi-
nal. This time, be sure to connect a load re_
sistor. (5Okil ohm)
b. Turn the equalizer selector to STD.
c. Playback the signals of BBBHz and 6.3kHz on
the test tape STD-341 and adjust the output
with the semi-fixed resistor for playback equa_
lizer adjustment so that the difference becomes
0 .
L - c h . . . . . V R - 1 0 4
R - c h . . . . . V H - 2 O 4
d. Depress the Equalizer Selector to Chrome and
confirm that the reproduced level at 6.BkHz is
-4.5dB t1.5dB compared with
that at B33Hz.
F i g . g
by
o
o
f
----+ F (Hz)
3 3
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