efinitive Technology says
that its bipolar speakers are
designed to create a spa-
cious, natural soundstage, closer to
that of a concert-hall performance
than that produced by most conven-
tional (forward-radiating) models.
The BP8, the newest addition to that
series, has two identical sets of speak-
er drivers in a single compact, unob-
Stereo Re
v
ie
w
T
EST
R
EPORTS
D
EFINITIVE
T
ECHNOLOGY
BP8 B
IPOLAR
L
OUDSPEAKER
“...an outstanding value among floor-standing loudspeakers.”
BP8 Bipolar Loudspeaker System.
Julian Hirsch, Hirsch-Houck Laboratories
D
trusive cabinet. One pair faces for-
ward conventionally, while the other
faces the rear, so that its direct output
is reflected from the wall behind the
speaker enclosure. The two sets of
drivers, which share a common enclo-
sure volume and port, operate in
phase (with their cones moving
inward or outward simultaneously),
so that their low-bass outputs tend to
reinforce each other instead of cancel-
ing as happens with dipole (out-of-
phase) radiators.
Each driver group consists of a sin-
gle 5 1/2-inch polypropylene-cone
woofer and a 3/4-inch soft-dome
tweeter with magnetic-fluid cooling
and damping. The crossover, at an
unspecified frequency, is of the
Linkwitz-Riley type to optimize the
phase and frequency response through
the crossover region. The enclosure
was designed with a newly developed
computer program and is said to rival
the bass-loading characteristics of a
transmission-line enclosure with a
simpler and less expensive cabinet.
Another goal of the BP8’s designers
was to minimize diffraction, com-
monly caused by grille frames and
external cabinet discontinuities,
which can alter a speaker’s imaging
characteristics. The BP8 is a colum-
nar design with rounded edges, just
wide enough to accommodate the
base drivers. Instead of having a con-
ventional grille, the entire cabinet
(except for its top and bottom) is
enclosed in a black (or, optionally,
white) fabric “sock” that fits snugly
around its full length and can be
rolled down for access to the drivers.
The top plate and the visible edges of
the base are finished in either glossy
black or genuine oak. The input con-
“Their imaging was excellent…
”
“…the BP8 has an exceptional
ability to absorb high-power
transients… they absorbed
1100 watts at 1 kHz without
difficulty.”
—Julian Hirsch
Latest BP8B speaker
is even better
