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lil. MEASURING
METHOD
TAPE SPEED DEVIATION
1.
Method involving use of pre-recorded tape
Playback a tape pre-recorded at 1000 Hz (+0.1%) on
recorder
to be tested.
Connect
the appropriate
output to a frequency counter meter in order to
measure the tape speed deviation.
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 measure-
ment 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%, and measure with a wow meter. It is also possible
for a 3,000 Hz sine wave to be recorded and played back
for measurement
with
a wow
meter.
In this case,
however, the wow meter will indicate a value as much as
twice that given in the specifications.
SIGNAL TO NOISE RATIO
1730-SS
ae
=
atv
Set the Equalizer Switch to the "7-1/2 ips" position and
playback a tape containing a 250 Hz sine wave recorded
at "Q' VU
level on a standard recorder. Connect a
V.T.V.M.
to the line output jack of the recorder and
measure its output. Next, remove the tape and measure
the noise level under the same conditions. Convert each
of the measured values into decibels.
TOTAL HARMONIC DISTORTION FACTOR
1 KHz
Audio
1730-SS
Distortion
Oscillator
meter
Connect the measuring instruments as shown above, and
record a 1,000 Hz sine wave at "0" 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 resultant distortion factor can be obtained from the
results of the above measurement by using the following
formula :
do = d—d, —d2
where,
do = Required
d = Overall distortion factor
d,; = Noise level
d2 = Distortion factor of the oscillator
(Note : New tape of particularly good quality should be
used for measurement of the distortion factor. Fuji L is
recommended).
POWER OUTPUT
Playback
a tape
containing
a sine wave
of 250 Hz
recorded at "0" VU ona
standard recorder.
Then use the following formula :
By
P = Desired output (W)
P=
E = Measured Voltage (R.M.S.)
R=8Q2
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