Legacy Empire Owner's Manual - page 12
2. Horizontal Biamping
Any two stereo amplifiers may be utilized in horizontal
biamplification. Many audiophiles prefer the "sweetness" of tubes on
the satellite portion of the loudspeaker while favoring the "control
and weight" of solid state amplifiers on the subwoofer section.
The biggest drawback of such a marriage of amplification is that
the two amplifiers may have different input sensitivities or output
polarities. Differences in the input sensitivities may be overcome by
using a dual amp balancer. This unit allows independent balancing of
the left subwoofer/satellite ratio and right subwoofer/satellite ratio.
It's also a good idea to check the owner's manuals to establish if
the amplifiers are inverting or non-inverting. If the two amplifiers are
of opposite polarity, then you should reverse the polarity at the inputs
of either the subwoofer or satellite binding posts.
NOTE: The above only applies to loudspeakers that incorporate the
subwoofer and satellite section in a single enclosure. It does not
apply towards the separate powered subwoofer/satellite configuration.
You must always observe the polarity when connecting the speaker
wire to a powered subwoofer.
ACTIVE BIAMPING
This option requires the utilization of an electronic (powered)
external crossover. Active biamplification is the most appealing
means of interfacing a subwoofer/satellite system due to the control
possibilities offered, but can also be the most costly.
An active crossover is inserted between the preamplifier outputs
and the inputs of two stereo amplifiers. Vertical or horizontal
biamping considerations are also applicable here.
A well designed active crossover will offer the user independent
high pass / low pass turnover frequencies for optimally blending the
satellites with the subwoofer sections of the speaker system. Other
features usually found are separate level controls for the high pass or
low pass sections and a choice of inverted or non-inverted low
frequency outputs (needed when strapping an amplifier to mono).
Also helpful is bass equalization and subsonic filtering.
When cascading active filters with the existing passive filters
within the speaker system, be sure to allow for adequate frequency
overlap. For instance, if the passive crossover is set at 500 Hz, select a
low pass corner frequency of 600 Hz and a high pass corner
frequency of 450 Hz to prevent a suck-out in the response at 500 Hz.
The controlled distribution of power afforded by the active
crossover results in less amplifier strain (better clarity), greater
dynamics, and lower intermodulation distortion. However, a basic
understanding of crossover slopes and crossover frequencies within
your loudspeaker will be needed to implement the active crossover
successfully.
10