4B
3
&
3B
3
Amplifiers
5
Connecting Audio Inputs
The Bryston Cubed amplifier can receive analog
audio from any preamp or surround processor with
volume controlled line-level outputs. Balanced XLR
and TRS as well as singled ended RCA inputs are
both available and can be selected using the Input
Select switch on the rear panel of the amplifier.
Balanced vs. Single Ended Input
The balanced input requires a balanced pre-amp
source. Balanced systems provide noise rejection
from external electrical interference, so cable
length can be very long—50 meters or longer. The
single ended or unbalanced input is provided for
pre-amps without balanced output. Single-ended
cables should be kept to 20 feet (6 meters) or less.
In general never use longer cables than necessary,
never coil excess cable length, and keep signal wires
away from AC power or speaker cables.
Power Conditioners
Bryston urges caution in choosing a power
conditioner for your audio/video system. Large
power amplifiers can draw very substantial current
from the wall plug, and many so-called power
conditioners can in fact hinder the supply of current
by inserting resistances in series with the line cord.
However, there are now power conditioners that
can reduce or eliminate RF and ‘hash’ from the AC
supply and may actually improve current delivery
to your system. This type of power conditioner
(exemplified by Bryston BIT products) uses the
energy storage in a large toroidal transformer to
provide high instantaneous power and reduce
the substantial AC output resistance of the wall
socket and house wiring. This resistance can be in
the range of 0.5 to 1 Ohm and is typically reduced
to only a few milliohms by the power conditioner.
That in turn considerably reduces voltage drop in
the power line on high current surges and quite
substantially increases the stability of the power line
improving audio (and video) focus, precision and
clarity.
External Control Voltage
To power-up the amplifier using an external control
voltage, supply a 5V to 12V (AC or DC) control
voltage to the ‘IN’ terminals of connector (
fig. 1
). Use
paired wire of 22 to 18 gauge between the source
device and the Bryston Cubed series amplifier. The
appropriate mating connector is supplied with each
amplifier.
Set the External Turn-On switch to “External” See
“10. Remote Power Up:” on page 9. Place the
front panel switch in the ON position. The amplifier
will now power-up only when the control voltage is
present (on). Immediately following power-up, the
control voltage will appear at the ’OUT’ terminals
of connector for the control of other equipment.
The removal of the control voltage (0v) causes the
amplifier to turn ‘off’, and the control voltage at the
‘OUT’ terminals is interrupted.
In the “Local” setting of the External Turn-On switch
the amplifier will ignore the control voltage and
power up only by using the front panel push-button
power switch. If a control voltage is present at the
‘IN’ terminals, it will still be available at the ‘OUT’
terminals after the power-up sequence.
Note:
The ‘OUT’ terminals are connected to the ‘IN’
terminals once the amplifier has powered-up.
The control current is determined by the source
equipment. The carrying current of the ‘OUT’ relay
is 2 amps. The amplifier’s control circuitry itself
draws less than 2 mA from the control current when
operating.
REMOTE POWER TURN-ON
PLUG-IN CONNECTOR
Insert stripped ends of insulated wires revealing
approx. 1/4" of bare, stranded copper wire between
24 and 12 AWG (.5mm to 2mm dia.) into open elevator
style wire clamps & tighten with a slot screw driver.
Do not over tighten or wires may eventually come
lose. Maximum tightening torque is 4.5 lb-in (0.5Nm)
Figure 1
