Akai X-165D Service Manual

Wl.
MEASURING
METHOD
TAPE SPEED DEVIATION
1.
Method
involving
use
of
pre-recorded
tape.
For
measuring
the
tape
speed
deviation,
play
back
a
pre-recorded
tape
at
1,000Hz
+
0.1%.
Connect
the
appropriate
output
to
a
frequency
counter
meter
in
order
to
measure
the
tape
speed
deviation
from
the
pre-recorded
tape.
2.
Method
involving
use
of
timing
tape.
(designed
for
tape
speed
measurement)
This
method
utilizes
a
timing
tape
marked
at
intervals
of
7-1/2”.
The
running
time
of
over
60
marked
sections
of
tape
is
measured
in
order
to
calculate
the
deviation
of
the
tape
speed.
In
applying
this
method,
however,
it
should
be
kept
in
mind
that
timing
tape
stretch
or
contract
measurement
error
is
inevitable,
so
that
it
is
necessary
to
measure
the
total
length
of
the
tape
in
advance.
WOW AND FLUTTER
Playback a 3,000 Hz pre-recorded tape of which the
wow and flutter level is guaranteed to be smaller than
0.07% for measurement by means of a wow meter. It is
also
possible
for
a
3,000
Hz
sine
wave
to
be
recorded
and played for measurement by means of the wow
meter. In this case, however, the wow meter indicates a
value as much as twice the value given in the specifi-
cations.
SIGNAL TO NOISE RATIO
X-165D
_
Set the Equalizer Switch to “7-1/2” ips position and
playback a tape containing a 250 Hz sine wave recorded
at “0” VU level on a standard recorder.
Connect a V.T.V.M. to the line output jack of th
recorder
and
measure
its
output.
|
Then remove the tape and measure the noise level under
the same condition. Convert each of the measured values
into decibels.
TOTAL HARMONIC DISTORTION FACTOR
1 kHz
Audio Distortion
Oscillator Meter
Connect the measuring instrument as shown above, and
record a 1,000 Hz sine wave at “OQ” VU. Playback the
resultant signal and measure the overall distortion factor.
Measure the noise level of the tape recorder with the
tape removed ; connect the audio oscillator directly to
the distortion meter for measurement of the distortion
factor of the oscillator.
The required distortion factor can be obtained from the
results of the above measurement by the following
formula.
do = d—d, —d,
where, do = Required
d = Overall distortion factor
d, = Noise level
d, = Distortion factor of the oscillator
(Note : New tape of particularly good quality should be
used for measurement of the distortion factor.)
POWER OUTPUT
Playback a tape containing a 250 Hz sine wave recorded
at O VU on a standard recorder.
Connect a V.T.V.M. to the line output jack of the
recorder and measure the voltage at the output of the
recorder to be tested.
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Akai X-165D Specifications

General

Brand	Akai
Model	X-165D
Category	Tape Deck
Language	English