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ll.
MEASURING
METHOD
1. TAPE SPEED
DEVIATION
3, FREQUENCY
RESPONSE
i
440
4400
Frequency
Aig
ara
ae
0
Line output
counter
requency
put
A
L input
Line
input
Oscillator
output
Fig. 1
'As shown in Fig. 1, connect a Frequency Counter
to the Line' Output of Model 4400. Take a frequency
counter reading at the beginning, middle, and end
of tape
winding
during
playback,
The
maximum
value of these respective readings will represent tape
specd deviation.
2. WOW
AND FLUTTER
4400
Line output
Wow and Flutter
Meter input
Method A
As stiown
in Fig. 2, connect
the Line Output
of
Model
4400
to
the
Input
of a Wow
and
Plutter
Meter. Use a 3,000 Hz pre-recorded test tape and
take a wow
and flutter meter reading at the begin-
ning, middle, and end of tape winding. The maximum
value of these respective readings will represent the
wow
and flutter.
Method B
Supply a 3,000 Hz sine wave signal from an Audio
Frequency
Oscillator
and
make
a recording
on
a
blank
tape
at the
beginning,
middle,
and
end of
tape winding.
Rewind
and Playback
tape. Measure
wow
and
flutter
with
a Wow
and Flutter Meter.
{The wow
and flutter value of Method B will be close
to twice that of Method
A.)
High Sensitivity
V.T.V.M,
Fig. 3
For
measuring
frequency
response,
connect
instru-
ments
as shown
in Fig. 3 and proceed
as follows:
1) Supply a 1,000 Hz sine wave to the Line Input
of Model 4400 from an Audio Frequency Oscil-
lator
through
an Attenuator.
Set recorder
to re-
cording
mode
and
turn
recording
level
volume
control to maximum.
Adjust Attenuator
to obtain
a +4 dB V.T.V.M.
reading.
2) Under conditions
described in 1) above, re-adjust
Attenuator so that the Line Output is —}@ dB,
and record 40 to '20,000 Hz spot frequencies.
3) Rewind
tape and playback
from
the beginning.
Take V.T.V.M.
spot frequency readings and plot
values on a graph.
NOTE:
When
measuring
frequency
response,
new
tape should be used.
4, SIGNAL TO NOJSE RATIO
aaa |
4400
Line output
High Sensitivity
V.T.V.M.
Fig. 4
As
shown
in
Fig.
4, connect
a High
Sensitivity
V.T.V.M.
to the Line output of Model
4400.
Play-
back a 250 Hz "0" VU pre-recorded
test tape and
measure
the output. Then
remove
the tape and
measure
the noise
level under
the same
condition.
Convert cach of the measured values into decibels.
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