-
necessary to record the test tape on the machlne
ltself and to take the measurements
durlng
replay
after
rewlrdlng the tape. Ilowever, no measurements
should
be taken
durlng the
recordlng
as
this
mlght lead to highly erron6ous
readlngs
because if half the capstanrs
clrcumference or an even
multlple there-of equals the dlstance between the record
ard
the replay head, the wow would
be
cancelled and lf the dlstance was an odd
multiple,
the effectlve value would
be almost doubled.
Iherefore,
the measured value
ls
the vector
sum
of the wow
ard
flutter
durlng
"record"
ard
the
wow and
flutter
durlng
"playback".
The
publlshed
values for the
STUDER
I-37
are based on thls
method
of
measurement.
Tape
sllp
-
the
change
in
absolute
tape
speed
from the
beglnnlng to the end of a
reel
-
ls measur-
ed by
recording
a test signal throughout a
reel
of tape or
Just
at
each erd. Turnlng the tape
head
to tail
places
the sectlon whlch was
recorded
at the start of the reel on lts end
and lt
ls now
played
backwards.
This
reverses
the condltlons of holdback tenslon under whlch the recordlng was made
and the
slight dlfference ln
recorded
wavelength wlll
now
be
reproduced
as a
frequency whlch differs from
the one that was recorded. The dlfference between the two frequencles
ln
the reversed reel
con-
dition
canbemeasuredonthe EMT 420,wow
andfluttermeterlnposltlon
"sllp".
Onehalf of
the tndlcated value ls the
amount
of tape sllp.
The
tape
sllp ls
very much
a
functlon of the type of tape
used, ln
partlcular
lts thlckness.
Note:
E
4
Alignment
of
Startlng and Brake Characterlstlcs
See
under
C
8
"Relav
Box"
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