Boston Acoustics 251 Speaker User Manual


 
2
Specifications 251 261
Frequency Response (±3dB) 66
20,000Hz 58
20,000Hz
Recommended Amplifier Power 10
100 watts 10
100 watts
Nominal Impedance 8 ohms 8 ohms
Sensitivity [1 watt (2.83v) at 1m] 89dB 90dB
Tweeter
3
4" (19mm) dome
3
4" (19mm) dome
Bass Unit 5
1
4" (135mm) copolymer 6
1
2" (165mm) copolymer
Crossover Frequency 6500Hz 6200Hz
External Dimensions (HxW) 9
1
2 x6
3
4" (241 x 171mm) 10
9
16 x7
3
4" (268 x 197mm)
Mounting Hole Cutout (HxW) 8
3
4 x5
3
4" (223 x 146mm) 9
7
8 x7
1
8" (251 x 181mm)
Mounting Depth (from surface) 2
5
8" (67mm) 2
7
8" (73mm)
Description
Boston Designer Series speaker systems are designed to be as accurate, clean, and musical as our
free-standing speakers. The unobtrusive, flush-mount design makes them ideal for installation
in walls or ceilings of rooms where space or decor make conventional speakers undesirable or
inappropriate. They can also be used for the front and/or rear channels in a home theater system.
The front surface is provided with a matte white finish. The speaker can be installed as is or can be
painted to match the room environment, using the supplied painting mask. The speaker grille is
removable, and is made of epoxy-painted galvanized steel.
Their smooth, detailed sound comes from two highly refined driver elements: a copolymer bass unit
with butyl rubber surround for powerful bass and natural midrange, and a
3
4-inch dome tweeter that
provides outstanding clarity and articulation. The tweeter and bass unit are mounted close together
in a point-source configuration for excellent imaging and extremely broad, uniform dispersion. This
is important, because wide dispersion gives you the flexibility to install the speakers where they look
the best (high on the walls, for example), yet still project clear sound throughout the listening area.
Both drivers are built in Boston’s state-of-the-art production facility to be within ±1dB of the labora-
tory reference, perhaps the industry’s tightest tolerance.