Using Passive Crossovers - Rockford Fosgate Power 250M Installation And Operation Manual

10. Perform a final check of the completed system wiring to ensure that all connections are
accurate. Check all power and ground connections for frayed wires and loose connections
which could cause problems.
NOTE: Follow the diagrams for proper signal polarity.
CAUTION: These amplifiers are not recommended for impedance loads below 2Ω.
!

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
12dB/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.
CAUTION: These amplifiers
!
are not
recommended for
impedance loads
below 2Ω.
L
6dB/Octave Low-Pass
Speaker Impedance
Freq.
2 OHMS
Hertz
L C
80 4.1mH 1000mF
100 3.1mH 800mF
130 2.4mH 600mF
200 1.6mH 400mF
260 1.2mH 300mF
400 .8mH 200mF
600 .5mH 136mF
800 .41mH 100mF
1000 .31mH 78mF
1200 .25mH 66mF
1800 .16mH 44mF
4000 .08mH 20mF
6000 51mH 14mF
9000 34mH 9.5mF
12000 25mH 6.6mF
L = Low-Pass (Inductor)
C = High-Pass (Capacitor)
For more information, see your Authorized Rockford
C
6dB/Octave High-Pass
4 OHMS
L C
8.2mH 500mF
6.2mH 400mF
4.7mH 300mF
3.3mH 200mF
2.4mH 150mF
1.6mH 100mF
1.0mH 68mF
.82mH 50mF
.62mH 39mF
.51mH 33mF
.33mH 22mF
.16mH 10mF
.10mH 6.8mF
68mH 4.7mF
51mH 3.3mF 100mH
Fosgate Dealer.
I
NSTALLATION
8 OHMS
L C
16mH 250mF
12mH 200mF
10mH 150mF
6.8mH 100mF
4.7mH 75mF
3.3mH 50mF
2.0mH 33mF
1.6mH 26mF
1.2mH 20mF
1.0mH 16mF
.68mH 10mF
.33mH 5mF
.20mH 3.3mF
.15mH 2.2mF
1.6mF
7