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Specifications subject to change without notice. Boston, and Boston Acoustics are registered
trademarks of Boston Acoustics ©1999 Boston Acoustics, Inc.
300 Jubilee Drive Peabody, MA 01960 978-538-5000 Fax: 978-538-5199
Crossover Schematic
The following is a low-pass crossover circuit engineered specifically for the 6.5LF. The low-pass filter has a
12dB/octave slope with a crossover point of 300Hz. This is very useful when added to systems that are lacking
low frequency output. Additionally, it may be used in vehicles that tend to absorb and attenuate mid-bass fre-
quencies. This is a common situation in passenger cars whose doors basically act as "bass traps."
WARNING: This circuit is designed for a single 6.5LF woofer. Two such circuits and woofers are required for a
stereo system. The impedance of the driver is a critical part of the completed circuit and each circuit must be
wired to only one woofer. If multiple woofers are desired, multiple crossover circuits need to be installed.
Crossover Components
It is important to maintain the component values listed in the parts
list. The inductor in the circuit (L1) has a steel laminate core, and a
very low DC resistance of 0.22 ohms. This low DC resistance is
critical for maintaining the sonic detail in the low frequencies, and
to avoid compromising the damping factor of the amplifier. The
damping factor is the ratio of the input impedance of the speaker
over the combined impedance of the output devices in the ampli-
fier and any resistance in the signal path between the amplifier
and the speaker.
Performance:
This circuit reinforces output below 300Hz in the system to which it is added. The amount of increase depends on
the other speakers in the circuit, as well as the amplifier(s) powering the speakers. If this driver and circuit are
added to an existing ProSeries 6.5 or 6.5
3
system with an additional amplifier of the same model, and increase of
6dB is possible. If this driver and circuit are added to the same amplifier powering the existing system, it is
important that the amplifier be capable of driving a 2-ohm impedance. Many high performance amplifiers are
capable of doubling their power at 2 ohms. In these cases, a 6dB increase will be realized. If the amplifier does not
double its power at 2 ohms, a smaller increase in output will result.
Part: Description:
L1 3.3mH Inductor, 0.22Ω DC Resisitance
Steel Laminate Core
C1 80µƒ Non-polar Audio Capacitor
50V Working Voltage
Specification: 6.5LF Woofer
Nominal Size 6
1
/2-inches (165mm)
Recommended Amplifier Power 20–500 watts
Nominal Impedance 3 ohms
Mounting Cutout Diameter 5-inches (127mm)
Mounting Depth 2
3
/8-inches (60mm)
Specification: Crossover
Crossover Frequency (-3dB down) 300Hz
Crossover Slope 12dB/octave