Proceed HPA2 - Manual (Page 17)

17
Bridged Operation
Your Proceed amplifier has been designed to be extremely versatile. Should your
needs change or grow over time, you may wish to add additional power by one
of two means: Bridging, or Biamping. We will discuss bridged operation first.
Bridging Explained Bridging refers to the act of reconfiguring the circuitry in two channels of your
amplifier to act as though it were a single, much larger amplifier. (Of course, this
reduces the number of available channels; you may need more amplifiers to
make up the difference.)
Bridging is accomplished by sending a normal signal to one channel and an in-
verted signal to the other. In this configuration, one channel will always be “push-
ing” when the other is “pulling.” By connecting the loudspeaker leads across the
left and right red output terminals, the amplifier can now deliver twice the nor-
mal voltage to the loudspeaker. Working together this way, the two amplifier chan-
nels can deliver about four times the power to a speaker that a single channel
could deliver on its own.
Bridged operation is particularly beneficial with low sensitivity, high-impedance
loudspeakers (8
Ω
or higher) that have a greater need for voltage than for current.
It is not recommended for low-impedance loudspeakers, as the speaker’s imped-
ance is “split” by the two halves of the amplifier. Thus the bridged amplifier “sees”
a 2
Ω
load when connected to a 4
Ω
loudspeaker. Delivery of high power into
such a low impedance creates a great deal of heat that needs to be dissipated.
(Of course, your amplifier is protected against overheating, but having an ampli-
fier shut itself down even temporarily can put a damper on the evening’s enter-
tainment.)
Balanced Bridging If your preamplifier has balanced outputs, you should use them. For this discus-
sion, we will assume that you are using a Madrigal Balanced Bridging Kit for
each channel to be bridged. (Alternatively, you may have custom cables built us-
ing your preferred wire and connectors, being careful to follow the wiring dia-
gram below.)