Akai M-9 - II. MEASURING METHOD; TAPE SPEED DEVIATION; WOW AND FLUTTER; SIGNAL TO NOISE RATIO

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TAPE SPEED DEVIATION
1, Method involving use of pre-recorded tape
Playback
on
the
tape
recorder
to
be
tested
a
tape
pre-recorded
at
1,000
cps
+
0.1%
for
measuririg
tape
speed
deviation.
Connect
the
appropriate
output
to
a
frequency
counter
meter
in
order
to
measure
the
tape
speed
deviation
from
the
resulting
devi-
ation
of
the
measured
frequency.
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
the
tape
over
60
marked
sections
is
measured
in
order
to
calculate
the
deviation
of
the
tape
speed.
In
applying
this
method,
however,
it
should
be
borne
in
mind
that
should
the
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
the
3,000
cps
pre-recorded
tape,
whose
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
cps
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
specification
on
the
first
page.
SIGNAL TO NOISE RATIO
M-9
Line output
Set
the
Equalizer
Switch
on
“7-1/2
ips”
position
and
playback
a
tape
containing
a
1,000
cps
sine
wave
recorded
at
“0”
VU
level
on
a
standard recorder.
Connect
a
V.T.V.M.
to
the
line
output jack
of
the 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
dedbels.
TOTAL HARMONIC DISTORTION FACTOR
1K%
Audio Distortion
Oscillator meter
Connect
the
measuring
instrument
as
shown
above,
and
record
the
1,000
cps
sine
wave
at
“0”
VU.
Playback
the
resultumt
signal
and
measure
the
overall
distortion
factor.
Measure
the
noise
level
of
the
tape
recorder
with
the
tape
removed;
connect
the
audio
os-
cillator
directly
to
the
distortion
meter
for
measurement
of
the
distortion
factor
of
the
oscillator.
> The required distortion factor,may be obtained from the.results of.the above measurement by the following formula.
d,= d—d,—d,
where, do= Required
d = Overall distortion factor
di= Noise level
d2= 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 sine wave of 1,000 cps recorded at 0 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 teseed.