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BRYSTON PREAMPLIFIERS
BP-25 and BP-20 Functions:
MPS-1 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.
GREEN indicates output is non-inverting polarity. YELLOW
indicates output has inverted polarity.
HEADPHONE OUTPUT (BP-25):
Allows monitoring of any input source with the use of head-
phones. It is recommended that you use headphones with input
impedances greater than 50 ohms for optimal performance. If
you wish to mute
your loudspeakers while listening to your
headphones simply engage the MUTE switch on the preamphi-
fier (LED turns red). Be sure #of to use your remote control
(use 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 indicates 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-nght chan-
nel levels. The
Balance Control
is a tailored-inflection
type
which has very gradual action near the center of rotation
allowing fine adjustments to the stereo mage. For convenience
the electncal center of the control is detented.
SOURCE: Rotary knob, determines which input will appear at
the "TO TAPE' outputs for recording or processing, as well as
determining which program is available at the Main outputs.
(When the
"TAPE/SOURCE'
switch is in 'Tape' position,
"TAPE FROM? inputs appear at Main Outputs).
MONO/STEREO
SWITCH:
'Stereo' position provides
two-channel stereo at the Main outputs. 'Mono' position sums
the main outputs to monaural.
The "TO TAPE? outputs are
always stereo. (Switch not present 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 SOURCE 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/out
switch for the external equipment.
REAR PANEL CONNECTORS:
BALANCED
OUTPUTS:
Output is taken from the three-
pin "XLR" type connectors. Pin-1 is ground - Pin-2 is the
positive (+) output and Pin 3 is the inverted 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 are two parallel unbal-
anced outputs for each channel available, utilizing gold-plated
RCA-style connectors. The output is always in-phase with the
input, and is capable of delivering 15 volts into any load of 600
ohms or greater.
TO-TAPE-FROM:
The 'TO TAPE' outputs are selected by
the rotary "SOURCE" knob and are provided as a recording
output. This feed is unaffected by the operation of other front
panel controls. The 'FROM TAPE' (unbalanced RCA) input is
useful for monitoring tape playback or processed signals. Mov-
ing the "T'ape/Source" 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 500mv, input impedance is 10K
ohms .
UNBALANCED INPUTS: Input connectors are gold plated
RCA Phono jacks. Input sensitivity is 500mv, input impedance
is 50K ohms. On BP-25P, Phono input impedance is 47K,
sensitivity is 5 mV.
On BP-25MC,
MMohms. Phono input is
as above, MC Phono input impedance is 180 Ohms, sensitivity
is 0.35 mV.
BALANCED INPUTS: Balanced input connectors are gold-
plated 3-pin "XLR" style connectors. Pin 1 is ground, Pin 2 is
positive input (+) and pin 3 is the inverting input (-). Input
sensitivity is 1 volt, input impedance is 15k
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