Bryston .5B Preamplifier User manual

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8RYSTON .58 PREAMPLIFIER
OPERATING INSTRUCTIONS

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MODEL .58
SIGNAL FLOW AND
SWITCHING DIAGRAM
TAPE DECK
-OR-
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TAPE IN
TAPE OUT
MAIN OUT
AC RECEPTACLES
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FUSE
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VOLUME
POWER PILOT
SWiTCH C
ON TROL SWITCH
TAPE B ALA NCE
MUTE
CONTROL
SW ITCH LIGHT
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/
/
(
RELAY
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TO AMPLIFIER
MODULES
SWITCHED IIUNSWITCHED
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TO OPPOS ITE CHANNEL
POWFR AMPLIFIER
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TAPE DECK - \ 6
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INPUT INPUT 2 INPUT 3 INPUT 4
TAPE OUT MAIN OUT
BALANCED OUTPUTS'
REPLACE
AC '
RECEPTACLES
ON
BP4 / BP4.2/BP5
MODELS ONLY
AB/BP4 -
.5B/BP5 -
BP4.2 -
50 Hz
&:
500 Hz
5B/BP5
ONLY
AU X
PHONO
LINE
1.
2120 Hz
TUNER
TUNER
LINE
2-
CD
CD/AUX
LINE 3
INPUT
INPUT 2
INPUT 3
INPUT 4
SEUECTOR
SWITCH
NOTES: D iagram depicts 1 channel only
" MONO and MUTE switches combined on .5B/BP5
• - balanced inputs on BP4.2. Monitors Line 1 only.
TAPE
TAPE
LINE 4
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RELAY
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BALANCE MUTE
CONTROL
SWITCH
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VOLUME
CONTROL
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TO OPPOSITE CHANNEL
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/
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~-------------------~
,
, MODELS
,
AB/.5B
: 120V
, ONLY
SWITCHED
£
UNSWITCHED I'
£ :
F US E
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PILOT POWER
UGHT SWITCH
MODEL .4B/BP4/BP4.2/.5B/BP5
Signal Flow and Switching Diagram
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The Bryston Model .5B is a
basic signal preamplifier with
switching facilities for a
simple, high
quality sound
system, including phono,
tuner, tape deck and CD/aux-
iliary. The included diagram
will illustrate the switching
functions of the Bryston
Model .5B preamplifier.
TAPE MONITOR FUNCTION
The tape
monitor switch
(labelled "Tape"), allows
monitoring, through the main
outputs, of whatever appears
at the tape inputs. Thus,
if a
tape recorder has a third,
playback head, this will allow
the audition of a tape recor-
ding as it is being made. Simp-
ly plug the
output from the
playback head
to the "Tape In-
put" jacks. Pressing the
switch activates the monitor
function.
TAPE LOOP
The tape switch also allows
for external processor looping.
A
noise reduction unit,
equalizer or other audio ac-
cessory is fed from the "Tape
Output' jacks, (which exit
prior to the volume control).
The processed
output from
the accessory is fed back into
the tape inputs. The tape
switch then allows the inclu-
sion
of the processor in the
signal path when pressed,
or
its exclusion from the signal
path when left in the 'Out'
position.
LOW FILTER
The inflection point of the
rumble filter has been chosen
at 31.7Hz
to correspond to the
lowest signal frequencies like-
ly
to be found in recorded
music, and
to a suggested
revision to the RIAA recording
curve for
LP discs. For these
reasons, and for the more im-
portant reason
of avoiding low
frequency transient overshoot,
ringing and phase misalign-
ment, the low filter is a
"minimum" type, with a
6dB/octave slope below
cutoff. This is quite effective in
reducing
subsonic woofer-
wobble and
its attendant inter-
modulation effects, however,
since the most problematic
turntable and warp-induced
rumble frequencies, in the
area of 2-5Hz, are reduced
an
average of about 20dB or a
factor
of 100 in terms of power
demand. The low filter
switch
is active in the 'In' position,
and affects only the phono in-
puts.
MUTE SWITCH
The listener often is called
momentarily away from
critical listening, to answer
the phone for example, and
wishes to reduce the gain for a
short time without disturbing
the volume control setting.
The
mute switch reduces
preamp gain by 20dB. Thus the
music may still
be heard, but
at a background level. This is
also useful for changing
records, cueing the stylus
manually to a particular song,
cleaning the stylus with a
brush, etc. The mute switch is
active in the 'In' position and
affects only the main outputs
without disturbing the tape
outputs.
MONO FUNCTION
Occasionally a system will
display some offset in gain
favouring one channel over the
other due to slight differences
in speaker
efficiency , dif-
ferences in room loading, or a
somewhat off-center listening
position dictated by room
decor . Thus it is convenient to
"mono" the signal to obtain
the most unambiguous center
image, convenient to ad-
justing the balance control.
For reasons
of simplicity ,
rather than having a separate
switch for this function, the
"Mute" switch aIso connects
the
two channels in Mono. Ob-
viously, the listener may wish
to advance the volume control
to provide sufficient level for
establishing center image. Do
not forget to reduce the
volume control again before
deactivating the mute
switch
in this case, or you may be
startled by the sudden in·
crease in sound level. The
balance control is a tailored
in-
flection type which has very
gradual action near the center
of rotation for fine ad-
justments to the left-right
balance of the stereo image.

ACCESSORY OUTLETS.
The . 5B i nc l udes two
3·prong grounded. 120 volt
receptacles on the rear panel,
one switched. one unswitch-
ed . Please observe the caution
printed below the receptables
regarding maximum power
draw from these outlets. Large
power amplifiers, especially
including the 8ryston models
38 and 48 should not be plug-
ged
into these receptacles. To
do so may damage the
preamp's power switch . It is
permissib le to plug the
Bryston 2B·LP into these
outlets , however, or any class
AB
amplifier up to 50 ,(or class
A
amplif ier up to 15 ) watts per
channel.
In general, it is inad-
visable to
switch large power
amplifiers on and off by the
swi
tch in a preamplifier, for
the above reason, and also
because it is likely to cause a
fluctuating voltage·drop on the
preamplifier's line cord, which
in worst case conditions can
become an audible problem.
TURN ON DELAY
The Model .5B
contains an
output shunting re lay with an
approximate 3-second delay at
turnon, to
allow any transient
thumps to settle . The re lay
opens instantly when the
preamp is
switched off to pre-
vent any power-supply decay
artifacts from appearing at the
outputs . The relay has multi·
pie gold
contact faces per
channel for
maximum long
term
reliability , and does not
appear in the signal
path when
the preamp is operating.
The
Point-five-B has been
designed from a rational,
function-oriented ideal of max-
imum musical accuracy, with
an absolute minimum of
uselsss gadgetry or ex-
traneous
controls . The signal-
handling
circuit is novel and
fundamentally correct, both
electronically , and more im·
portant,
sonically . We believe
you will find a renewed sense
of awareness of the musical
enjoyment in your
music col-
lectio
n, played through your
Bryston preamplifier. Even
your tuner will sound cleaner
and more musically
transparent than you may
have exprienced before.
Please do not
hesitate to
write us if you have any ques-
tions or comments about any
of our products. Your opinion
is important to us.
57 WESTMORE DRIVE, R8<DALE, ONTARIO, CANADA M9V 3Y6 TELEPHONE: 416-745·1800, TELE X: 06 ·989548
IN THE U.S.
A. TELEPHONE: 802· 223-B159
e. G. J/ B5