22
Biamplification
In contrast to bridged operation (wherein a two channel amplifier is “fooled”
into behaving as a single, larger amplifier), biamplification makes use of a
two-channel amplifier to drive
different portions
of a single loudspeaker. As
with bridging, it offers a modular way of increasing the overally performance
of your system (if your loudspeakers support biamplification).
Since each channel of the amplifier is delivering current into its load only over
a limited range of frequencies (typically bass
vs.
mids and treble), several
forms of distortion are reduced as compared to each channel handling the full
range of musical information. For this reason, many loudspeaker companies
are designing their products to include multiple speaker inputs (since using
multiple amplifiers improves the performance of their products as well). An-
other common use of biamplification involves adding a subwoofer (along with
an appropriate electronic crossover) to supplement and/or improve the deep
bass performance of your system.
Always refer to the specific directions provided by your loudspeaker manufac-
turer prior to setting up a biamplified speaker system. Any instructions con-
tained herein cannot be substituted for those that are specific to the loud-
speaker in question. In general, however, biamping is done in one of two
ways:
active
biamplification, or
passive
biamplification.
Active biamping refers to the presence of an “active” electronic crossover that
divides the music into two (or sometimes more) bands of frequencies. These
are then forwarded to separate power amplifiers, and sent on directly to the
appropriate drivers in the speakers. The most common application of this ap-
proach is the use of a subwoofer crossover to separate the deep bass (below,
say, 80 Hz) from the rest of the program material. It is then amplifed sepa-
rately and sent to a dedicated subwoofer designed to handle those extremely
low frequencies.
Apart from adding a subwoofer, the next most common form of biamping
(called
passive
biamplification) involves merely using a conventional “Y-
adapter” (either balanced or single-ended) to provide a full range signal to two
channels.
Balanced Y-adapter
2 1
3
1 2
3
1 2
3
Female XLR Input
Pin 1: signal ground
Pin 2: (non-inverting)
Pin 3: signal – (inverting)
Male XLR Output
Pin 1: signal ground
Pin 2: (non-inverting)
Pin 3: signal – (inverting)
Male XLR Output
Pin 1: signal ground
Pin 2: (non-inverting)
Pin 3: signal – (inverting)
The outputs of these two channels are then connected to two sets of binding
posts on each loudspeaker. (See below.) The loudspeaker’s internal crossover con-
tinues to divide the frequencies appropriately among the various drivers.
