Advent 100A Owner's Manual page 11

Notes About Calibration
Thi ection will an wer ome of the question you
may have about the calibration procedure. We've also
provided ome sugge ti.on which may make your u e of
the Model lOOA more atisfying.
1. During the Record Calibration, when you were
reading the level of the REC CAL TO E coming off
the tape, you may have noticed the Dolby Level meter
fluctuating slightly. This is u ually due to irregularities
in the oxid
urface of th tape itself. If the recorder'
h
ad are cl an, the
e fluctuation should rarely be more
an the range indicated by the two mall dots on either
id the Dolby Level line. These dot r present a
ran ge of about 2 dB, which i well within the matching
1
el tolerance of the Dolby System. It
i
rare, even with
th be t tape, to always be preci ely on the Dolby Level
lin . Slight variation are inaudible and you will have to
tolerant of them, as is the Dolby Sy tern.
However, if the meter fluctuation are per istent
and large, that is, well below the left hand mall dot on
the meter, we uggest that you not use that reel of tape.
Fluctuations of this sort indicate tape "dropout" that
would be audible on any recording you made.
8
NORMAL MODE
2.
If
you own a three-head recorder capable of mon-
itoring the tape while recording, and if you are con-
cerned with getting the last ounce of performance from
your recorder and the Model lOOA, we sugge t that you
make a quick Record Calibration for each reel of tape that.
you u e. It take only a few seconds.
If
you decide to do this, we'd al o sugge t one
further step. After you do the Record Calibration for a
particular reel, we suggest that you actually leave
10 econds or o of the REC CAL TONE at the begin-
ning of the tape. Having this tone at the beginning of the
recording will greatly facilitate making a copy of the tape
later, using the method described on page 15 .
If
you have a recorder which does not allow you to
monitor the tape with a separate playback head, we
doubt it would be worth the trouble to re-calibrate with
every reel , if you stick to the ame type and brand of
tape. However, if you change to another type or brand
of tape, you should re-calibrate.
3. Once you have uccessfully completed the Record
Calibration, you have essentially duplicated the Dolby
Level tape supplied with the Model lOOA. Therefore,
by imply repeating the Record Calibration you can
make your own Dolby Level tape of any length desired.
Remember, however, that if your recorder i quarter
track, thi homemade Dolby Level tape is not uitable
for u e on half track and full track machine and vice
versa.
4. Remember that if Play Calibration require read-
jusbnent, you must then check the Record Calibration
again. Also, any time you decide to fully calibrate your
recording system, the Play Calibration alway precede
the Record Calibration.