Bryston 270 User Manual

Model 270

Single Channel 70V Output Power Amplifier

GENERAL DESCRIPTION

Bryston's 270 power amplifier is a "70 VOLT" monaural version of the 2B and consists of a single amplifier
module - with a "42v power supply - which can deliver 65 watts into 8 ohms (120 watts into 4 ) via the
DIRECT output or into 60 watts via the 70 VOLT output transformer.

CLIPPING INDICATORS

The 270 amplifier uses a 2 colour LED with green indicating power on and red indicating actual overload
or distortion.. Once the indication contains a substantial red content it should be considered as a sign that

the level is too high and may cause speaker damage if allowed to continue.

INPUT CONNECTORS

The 270-PRO is supplied with a combination 3 pin balanced XLR and 3 conductor ¼” Phone jack. Onthe
XLR jack, pin 1 is ground, pin 2 is POSITIVE & pin 3 is NEGATIVE). On the phone jack, TIP is positive,
RING is negative & the sleeve is ground. Fully discrete active input circuitry is used; i.e. no transformers.
The 270-REG is supplied with an unbalanced RCA/phono jack.

All input connectors are gold plated and should be used only with quality gold plated input cable connectors
as a poorly plated connector will eventually corrode through the gold flash. Bryston makes cables with
appropriately heavily plated, high quality connectors, available through your dealer.

OUTPUT CONNECTORS

The 270 is equipped with four binding post terminals (2 red, 2 black) which can accept either standard
banana plugs or bare wire. One BLACK/RED pair is the DIRECT output and the remaining pair is the 70
VOLT output (see rear panel for wiring instructions). Since the binding posts are gold-plated we recommend
gold-plated banana plugs be used for the lowest distortion.
N.B. Do not attempt to remove the red or black connector nuts from the binding post connectors. They

are not removable and attempting to force them off may break the connector or strip the threads.

OUTPUT CABLES

For some time there have been available on the market special speaker cables constructed for extra high
current and low loss and distortion. These cables will cause no difficulty or instability with any Bryston
amplifier. In fact, we recommend that low inductance cables be used for the smallest loss of signal between
amplifier & speaker.

GROUNDING and the GROUND SWITCH

The left most switch on the rear panel is a GROUND LIFT switch. It is connected between the chassis
ground (including the third prong on the power line cord) and the signal ground. This switch is normally left
in the connected position . Occasionally a multi-amplifier rack installation, or an unusual grounding
situation with a preamp using a three wire power line cord, will cause a ground loop between the signal
ground and the chassis ground. This switch will allow the elimination of the resulting hum in such cases
without resorting to a "cheater" plug by switching to the separated position . Note that this switch does
not disconnect the chassis from the third prong on the power line cord which must be left intact for safety
reasons.