Bryston BHA-1, Руководство пользователя

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BHA-1
HEADPHONE AMPLIFIER
DRIVING MULTIPLE PAIRS OF HEADPHONES
While the BHA-1 is capable of driving multiple pairs of headphones from its three outputs (single 4 pin
XLR jack, dual 3 pin XLR jacks and 1/4” stereo phone jack) the total power delivered should be less than
or equal to the rated output power in order to maintian optimum performance. While more power can be
delivered, this will cause the class A amplifier stages to run hotter and performance may suffer. The inter-
nal heat generated is primarily determined by the power delivered to the load(s). Unfortunately there is
no easy way to determine in advance how much power headphones would be using as this would require
knowing not only the load impedances but also the output voltage levels and that is determined by listen-
ing levels in conjunction with the headphones’ effeciency.
Note that the three outputs are in parallel being driven from the same output amplifiers. Also, though we
recommend that the load impedance be greater than 32 Ohms it can be a low as 16 Ohms.
To connect multiple pairs of un balanced headpones DO NOT use the balanced output jacks as this could
damage the BHA-1. Each half of either balanced output is driven from a separate amplifier in a bridged
configuration (for a total of 4 output amplifiers) and thus there is no common ground. Un balanced (also
refered to as single ended ) headphones should only be connected to the un balanced output connector
(a 1/4” 3-conductor phone jack on the front panel). A suitable “Y” adaptor to facilitate driving two un bal-
anced headphones from the unbalanced output jack to is shown below. This is a typical “Y” adaptor and
should be readily available.
WIRING HEADPHONES FOR
BALANCED OPERATION
For headphones that have a separate pair of wires
(+ and - phase) from each side, maximum per-
formance can be obtained by wiring these head-
phones for fully balanced operation where there is
no common or shared ground.
The BHA-1 provides two different connector op-
tions for balanced operation:
1) Using a single 4 pin XLR connector (e.g. Neu-
trik NC4MC-B), the left driver is connected as
follows:
LEFT + → pin 1 RIGHT + → pin 3
LEFT – → pin 2 RIGHT – → pin 4
2) Using two 3 pin XLR plugs (e.g. Neutrik NC3MX-B) wire the two connectors as follows:
LEFT connector + → pin 2 RIGHT connector + → pin 2
LEFT connector – → pin 3 RIGHT connector – → pin 3