Definitive Technology BP10B - Manual

E F I N I T I V E

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E C H N O L O G Y

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first product is an unusual loud-
speaker that offers exceptional
p e r f o r m a n c e f o r i t s s i z e a n d

price. The BP10 is a slender columnar speaker
m e a s u r i n g 4 2 i n c h e s h i g h , 9 i n c h -
e s w i d e , a n d 1 1 1 / 2 i n c h e s d e e p a n d
weighing about 60 pounds. Its exterior is
c o m p l e t e l y b l a c k , a n d t h e f o u r s i d e s a r e
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
g o l d - p l a t e d , m u l t i w a y t e r m i n a l s , w h i c h
a c c e p t d u a l b a n a n a p l u g s , a r e u n d e r t h e

Stereo Re

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EPORTS

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EFINITIVE

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ECHNOLOGY

BP10 B

IPOLAR

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PEAKER

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YSTEM

“...a truly outstanding speaker system.”

Julian Hirsch, Hirsch-Houck Laboratories

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base, with a slot for the connecting cable.

T h e r e i s n o v i s i b l e i n d i c a t i o n o f t h e

number, size, or configuration of the driv-
ers. Actually, the BP10 is a bipolar system
(hence the “BP” designation) containing a
p a i r o f i d e n t i c a l t w o - w a y s p e a k e r s . O n e
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-
c a t e d a t t h e t o p o f t h e c a b i n e t a n d t h e
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
f r o m a w a l l — u n l i k e p l a n a r s y s t e m s ,
w h i c h m u s t n o r m a l l y b e p l a c e d s e v e r a l
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-
c o r d i n g t o t h e m a n u f a c t u r e r , t h e b a s s -
tuning system was computer-designed to
d u p l i c a t e t h e l o a d i n g o f a t r a n s m i s s i o n -
line system in respect to its bass response
and transient behavior while retaining the
a d v a n t a g e s o f a s i m p l e r a n d l e s s e x -
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
p a n e l s o f 1 - i n c h - t h i c k M e d i t e ( a h i g h l y
rigid composition material) and extensive
i n t e r n a l b r a c i n g . T h e c a b i n e t ’ s r o u n d e d
edges and narrow profile, plus its frame-
l e s s c l o t h g r i l l e “ s o c k , ” a r e d e s i g n e d t o
minimize diffraction, which can impart a
boxy coloration to the sound and mar the
spatial imaging.

I f i t b e c o m e s n e c e s s a r y t o r e p l a c e 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-
m o v e d f o r a c c e s s t o t h e d r i v e r s o r t h e
crossover network. The designers chose a
f o u r t h - o r d e r L i n k w i t z - R i l e y n e t w o r k t o
g i v e t h e B P 1 0 u n i f o r m r e s p o n s e i n t h e
c r o s s o v e r r e g i o n a s w e l l a s o p t i m u m
phase and transient response. The cross-
o v e r f r e q u e n c y i s n o t s p e c i f i e d , b u t o u r
measurements suggest that it is in the vi-
cinity of 2,000 Hz.

T h e B P 1 0 u s e s r u g g e d , h i g h - q u a l i t y

d r i v e r s . T h e w o o f e r s h a v e c a s t -
magnesium baskets, mineral-filled homo-
p o l y m e r c o n e s w i t h b u t y l r u b b e r s u r -

“Definitive Technology’s
first product is an unusual
loudspeaker that offers
exceptional performance…”

Latest BP10B speaker

is even better