General; Adjusting The Sensitivity Of The; Inputs; Adjusting The Sensitivity Of The Remaining - Revox B251 Operating Instructions Manual

3
ADJUSTING THE SENSITIVITY
OF
THE
INPUTS
3.1
General
The input of the
REVOX
8251 amplifier can
be
individually
matched to any audio source. The
factory
adjusts all inputs to
the nominal values (refer to specification sheet). lf
pronounced
volume differences occur when switching
from one input
to
another (compare with a loud passage), the inputs should
be
readjusted.
The
tape inputs should
be
measured
first. To ensure
maximum
operating safety when making tape
copies,
the tape outputs of
the amplifier are cross-connected. The internal measuring cir-
cuit therefore measures
the sum of
both outputs. This means
that only
one
input
after
the other should
be
measured because
an
incorrect value
would
be obtained if both tape units
were
si-
multaneously in
operation. Only the tape recorder
from which
the signals are
measured should
be
switched
on.
After the tape
inputs have
been measured and matched to
each other,
one of
the
two
can
be used as a
rererence for calibrating the other in-
puts.
lf no
tape
recorder
is
connected.
the most
frequently
used
audio
source
(tuner. turntable,
etc.)
can
be used
as
the reference
and
Section 3.2 can be skipped in its
entirety.
The subsonic
filter
which protects the
speaker systems from
distortions occuring from rumble
pulses (SUBSONIC button
[3]
pressed),
can be
program
assigned
to any input. lt
is
especially
useful
for
PHONO inputs. For
this
reason
the programming pro-
cedure
is
only
explained
in
the section'Adjusting the sensitivity
of the
PHONO input". The
subsonic
filter cannot be used
for
TABE COPY function.
Buttons [20] trough
[22]
activate functions
with which
settings
can be reprogrammed.
lf
the settings only
need
to
be
checked
rather than reprogrammed. the function can be
cancelled
by
pressing the corresponding button
again.
3.2 Calibrating and
adjusting the tape inputs
Note: most reel-to-reel and cassette recorders
are
equipped
with
an
output
level
control.
You
should
be
familiar
with
its
ope-
ration. Before the subsequent adjustments are performed.
en-
sure that the
tape inputs (on the amplifier) are
set
to
medium
sensitivity (press buttons
SENSITIVITY INPUT
[20]
and VO-
LUME
[25]
and alternately the monitor buttons
TAPE
1
[31] and
f
APE2[34].
The
f
lashing dot should
be in the 12th
position
of
the
display.
Correct
with
buttons
[28]
and
[29]
and save the
setting
by pressing
the
STORE button [23]).
3.2.1
Procedures
-
Select
tape input
1
(press
TAPE 1 [31]).
-
Switch on
tape
recorder
1
and
start in
play
mode
(program
material:
optimum
recording level
with
loud
passages).
-
Press
the
amplifier buttons SENSITIVITY INPUT
[20]
and
LEVEL
[24].
-
Adjust output
level
control
of
tape recorder
in
such
a
manner
that the loudest
passages produce
a 0
dB reading
on
the
am-
plifier
display.
-
Switch tape recorder
1
off and repeat
the
foregoing steps
with
the second
recorder.
Exception:
lf
one (or both) recorders
are
not equipped
with
an
output level
control, use this
(or the most frequently used
unit)
as
the refer-
ence
for
comparison.
t20l
l27l
l23l I24l
3.3
Adjusting the sensitivity of the remaining inputs
It
is important that all audio sources reproduce approximately
the same program material (e.9. loud
passages of
classical
music).
10