BRYSTON
PREAMPLIFIERS
BP-25 and BP-20 Functions:
BP-PS
POWER
SUPPLY
LED
indicates
GREEN
when
power
on
. Provides
12-
Volt
supply for
remote
turn-on
of
Bryston
THX
power
amplifier(s)
or
others
so equipped.
PREAMPLIfIER
LED:
Indicates
RED
when
output
muted.
GRI~EN
indicates
output
is
non-inverting
polarity.
YELLOW
indicates o
utput
has
inverted
polarity.
HEADPHONE
OUTPUT
(BP-25):
AJlows monitori.ng
of
any
input
source with the use
of
head-
phone,.
I t
is
recommended
that
you use
headphone
s with
input
impedances greater than 50
ohms
for optimal p
er
formance.
If
you wish to
mute
your
loudspeakers
while listening to
your
he;adphones simply engage the MUTE switch
on
the preampli-
[ler (
LED
turns red) . Be sure
not
to use
your
remote
control
(usc the front panel
volume
control) to adjust the volume while
listening
to
your
headphones,
as
the
remote
will
'
unmute'
the
preamplifier on
'volume
up'.
FRONT
PANEL
CONTROLS:
MUTE/NORMAL
TOGGLE:
Mutes
or
releases
mute
at
the main
outputs,
(not
'To
Tape'
outputs),
without
changing
the volume control setting,
each
time
pushed.
POLARITY
/INVERT
TOGGLE:
Reverses polarity at main
outputs
each time
pushed.
(GREEN
LED
indicates positive
polarity,
YELLOW
LED
i.ndi
ca tes inverse polarity).
VOLUME:
Rotary
control
varies the
output
level to the
'MAIN
OUTPUTS',
(does
not
effect
'TO
TAPE
'
outputs).
BALANCE:
Rotary
control
adjusts the left-versus-right
chan-
nel leve
ls
.
The
Balance
Co
ntrol is a tailored-inflection type
wruch has very gradual action ncar the
center
of
rotaDon
all
owing fine adjustments to the
stereo
image. For
convenience
the elect.rical
center
of
t.he
control
is
detented
.
SOURCE:
Rotary
knob,
deteani.nes which
input
will
appear
at
the
'TO
'["APE'
outputs
for recordi.ng
or
processing, as well as
detennini.ng which
program
is
available
at
the Main
outputs.
(
When
the
'TAPE/SOURCE'
switch
is
in
'Tape'
position,
'TA.PE
FRO
i
v!
' inputs
appear
at Main
Outputs)
.
MONO/STEREO
SWITCH:
'Stereo'
position
provides
two-channel
stereo
at
the Main
outputs.
'
Mono'
position s
LIms
the main OLltputs to monaural.
The
'
TO
TAPE'
outputs
are
always stereo. (Switch
not
pres
ent
on
BP
-25MC).
PHONO
SWITCH
(BP-25MC
only):
Allows the selection
of
either Moving-Magnet
or
Moving-Coil
phono
. (BP-25MC
preamplifiers are
equipped
with a
Phono
MM / MC switch in
place
of
the
Mono/Stereo
switch).
TAPE/SOURCE
SWITCH:
Source (down) position
moni-
tors whichever
input
is selected at
the
rotary
SOU
RCE
selector
knob.
Tape
(up)
position
provides
monitoring
of
the
'FROM
TAPE'
input
for
A/B
comparison
with the source. Should
an
external
processor
or
equalizer be
connected
in the
TAPE
LOOP,
the
"TAPE/SOURCE
" switch
will
act
as
an
in
/ou
t
switch for the external equipment.
REAR
PANEL
CONNECTORS:
BALANCED
OUTPUTS:
Output
is
taken from the three-
pul
''XLR''
type
connectors.
Pin-! is
ground
-
Pin-2
is
the
positive
(+)
output
and Pin 3 IS the i.nverted
output.
The
output
is
"ACTIVE
BALANCED"
(no transformer).
Never
connect
pin
2
or
pin
3
to
each
other, to
pin
1,
or
any
ground.
The
outputs
are capable
of
driving 30 volts to any
load 600
ohms
or
greater in balanced operation.
UNBALANCED
OUTPUTS:
There
nre two parallel unbal-
anced
outputs
for each channel available, utilizi
ng
gold-plated
RCA-style connectors.
The
output
is always in-phase with the
input, and
is
capable
of
deliveri.ng 15 volts into any load
of
600
oruns
or
greater.
TO-TAPE-FROM:
The
'TO
TAPE'
output
s are selected
by
the rotary
"SOURCE"
knob
and are
provided
as
a recording
output.
This
feed
is
unaffected
by the
oper
ation
of
other
front
panel
controls
.
The
'FROM
TAPE'
(unbalanced RCA)
input
is
useful for monitori.ng tape playback
or
processed
signals. Mov-
ing the
"T
ape/
So
urce"
toggle to
'Tape'
(up) position monitors
the recorded signal
on
recorders
equipped
with a separate
playback head,
or
the
processed
signal when using a signal
processor.
Input
sensitivity
is
SOOmv,
input impedance
is
10K
oruns.
UNBALANCED
INPUTS:
Input
connectors
are gold plated
RCA
Ph
ono jacks.
Input
sensitivity
is
SOOmv,
input
impedance
is
SOl( oruns.
On
BP-25P,
Phona
input
impedance
is
47K,
sensitivity
is
5
mV
.
On
BP-25MC,
MMohms.
Phona
input
is
as above,
rv
rc
Phono
input
impedance
is
180
Ohms,
sensitivity
is
0.35
mV
BALANCED
INPUTS:
Bala
nc
ed
input
connectors
are gold-
plated 3-pin
"XLR"
style connectors. Pin 1
is
ground, Pin 2 is
po
sitive
input
(+) and pin 3 is the inverting
input
(-).
Input
sensitivity is ! volt,
input
impeda
nc
e is
15k
Page 5
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