Definitive Technology BP10B User Manual

E F I N I T I V E

T

E C H N O L O G Y

’

S

first product is an unusual loud-
speaker that offers exceptional 
performance for its size and 

price. The BP10 is a slender columnar speaker
measuring 42 inches high, 9 inch-
es wide, and 11 1/2 inches deep and 
weighing about 60 pounds. Its exterior is 
completely black, and the four sides are 
covered by a fabric sleeve that fits snugly
around the enclosure. The wood base and 
top plate have a glossy lacquer finish. The 
top cap is also available in solid oak. The 
gold-plated, multiway terminals, which 
accept dual banana plugs, are under the 

D

base, with a slot for the connecting cable.

There is no visible indication of the 

number, size, or configuration of the driv-
ers. Actually, the BP10 is a bipolar system
(hence the “BP” designation) containing a 
pair of identical two-way speakers. One 
faces forward conventionally, and the oth-
er is on the rear panel, facing backward. 
Each consists of a 6 1/2-inch woofer and a 
1-inch dome tweeter, with the woofer lo-
cated at the top of the cabinet and the 
tweeter just below it.

Since the front and rear halves of the 

system radiate in phase over their full fre-
quency range, their bass outputs augment 

each other. In this respect, the BP10 is un-
like dipole radiators such as large electro-
static speakers or similar planar systems 
in which the front and rear surfaces radi-
ate out of phase and tend to cancel each 
other at low frequencies. Another result of 
the BP10’s bipolar design is that it oper-
ates best placed about 8 to 12 inches out 
from a wall—unlike planar systems, 
which must normally be placed several 
feet away from a wall.

The BP10’s two woofers share a com-

mon enclosure vented by a single ducted 
port at the bottom of the rear panel. Ac-
cording to the manufacturer, the bass-
tuning system was computer-designed to
duplicate the loading of a transmission-
line system in respect to its bass response 
and transient behavior while retaining the
advantages of a simpler and less ex-
pensive cabinet.

There was no skimping on the design of

the cabinet, however. Its sides are made of
3/4-inch particleboard, with front and rear 
panels of 1-inch-thick Medite (a highly 
rigid composition material) and extensive
internal bracing. The cabinet’s rounded 
edges and narrow profile, plus its frame-
less cloth grille “sock,” are designed to 
minimize diffraction, which can impart a 
boxy coloration to the sound and mar the 
spatial imaging.

If it becomes necessary to replace a 

driver or perform other internal servicing 
of the speaker, lifting the top plate reveals 
the drawstring that keeps the grille snug to 
the cabinet. After the drawstring is loos-
ened, the grille can be slipped down or re-
moved for access to the drivers or the
crossover network. The designers chose a
fourth-order Linkwitz-Riley network to 
give the BP10 uniform response in the
crossover region as well as optimum 
phase and transient response. The cross-
over frequency is not specified, but our 
measurements suggest that it is in the vi-
cinity of 2,000 Hz.

The BP10 uses rugged, high-quality 

drivers. The woofers have cast-
magnesium baskets, mineral-filled homo-
polymer cones with butyl rubber sur-