Advent 100A Owner's Manual page 9

Calibration
What thi calibration is all about.
you can ee from
th~
earlier description of how
th Dolby y tern works, the noise reduction is accom-
. h d by proce ing the signal that is fed to the
recorder, and then decoding that signal as it comes off
the ta
t th
time of playback. The optimum perform-
ance o(the Do lb
circuits depends on proper matching
of the le ls
to
the
record and play halves of the system,
which
are identic' circuits u ed in a mirror-image
relation hip to h other. An initial set-up and calibra-
tion
p ·
ur
is
th
r
fore nece sary after the Model
100 and your .r order ha e been interconnected.
Th
r
after, certain control ettings, including virtually
al] those
on
Otir ta r order, hould not be changed.
The in tru
ti n
ll str s
hich of these controls
h
ul
not be changed
.
ODE witch in the
onto your recorder
. et the recorder to
rding.
recorder:
ut volume controls,
read th playback signal,
6
-
..
set the output volume controls to about 2/3 of
their full rotation. (If you own a T db rg d
k,
set the output volume controls all th way up.)
c. If your recorder has output volume co tro and
the meters do read on playback, play th
Dolby Level tape and adju
t
th
1um
controls o thatthe record r's m t r r d to
"O".
5. Play the Dolby Level tap or cassette. it p lay ,
watch the Dolby Level meters on the Model 1 , and
adjust the ModellOOA' s P Y AL control (u ing a
small screwdriver) o that each meter reads to th large
Dolby Level line.
This completes the Play Calibration. From now on,
be sure that you do not change the etting of th
recorder's output volume controls (if any) or th Model
lOOA's PLAY C controls. This calibration is extr m l
stable and should not have to be rep ated, except to
periodically check it. If your recorder has output olume
controls, we suggest that you mark their setting with a
felt tipped pen, or even put household tap over th
controls as a reminder not to touch them.
ote: Be sure to treat your Dolby Level tap
respect. In particular, do not get them clo e to an
strong magnetic fields, such as the amplifier'
former, headdemagnetizers, or peakerm gn
demagnetization may result, ther by low rin
th
of the tone on the tape · gnificantly below the
lished standard for all products and prerecord d tap
employing the Dolby
y
em.