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USING PASSIVE CROSSOVERS
A passive crossover is a circuit that uses capacitors
and/or coils and is placed on speaker leads
between the amplifier
and speaker. The crossover delegates a specific range of frequencies
to the
speaker for optimum
driver performance.
A crossover network
can perform one of three functions:
High-Pass (capacitors),
Low-Pass (inductors
or coils) and Bandpass (combination
of capacitor
and
coil).
The most commonly
used passive crossover networks are 6dB/octave
systems. These are easy to
construct and require one component
per filter. Placing this filter in series with the circuit will
reduce power to the speaker by 6dB/octave
above or below the crossover point depending
on
whether
it is a high-pass or low-pass filter. More complex
systems such as 1 ZdB/octave
or
18dB/octave
can cause impedance
problems if not professionally
designed.
Passive crossovers are directly dependent
upon the speaker's impedance
and component
value for
accuracy. When passive crossover components
are used in multiple
speaker systems, the crossover's
effect on the overall impedance
should be taken into consideration
along with the speaker's
impedance
when determining
amplifier
loads.
A
CAUTION:
These amplifiers
are not recommended
for impedance
loads below
2Q
stereo
and 4Q bridged.
m g \
6dB/Octave
Low-Pass
LdB/Octave
High-Pass
L = Low-Pass (Inductor)
C = High-Pass (Capacitor)
For more information,
see your
Authorized
Rockford
Fosgate Dealer.
%eq.
Speaker Impedance
iertz
2
OHMS
4
OHMS
8
OHMS
@momom
80
4.lmH
1OOOmF
8.2mH
500mF
16mH
250mF
100
3.lmH
800mF
6.2mH
400mF
12mH
200mF
130
2.4mH
6OOmF
4.7mH
300mF
1OmH
150mF
200
1.6mH
400mF
3.3mH
200mF
6.8mH
1OOmF
260
1.2mH
300mF
2.4mH
150mF
4.7mH
75mF
400
.8mH
200mF
1.6mH
1OOmF
3.3mH
50mF
600
.5mH
136mF
l.OmH
68mF
2.0mH
33mF
800
.41mH
1OOmF
.82mH
50mF
1.6mH
26mF
1000
.31mH
78mF
.62mH
39mF
1.2mH
20mF
1200
.25mH
66mF
.51mH
33mF
l.OmH
16mF
1800
.lbmH
44mF
.33mH
22mF
.68mH
1OmF
4000
.OSmH
20mF
.16mH
1OmF
.33mH
5mF
10
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