Rockford Fosgate 351M - Manual (Page 7)

7
I
NSTALLATION
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 2
Ω.
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 2
Ω.
!
80 4.1mH 1000µF 8.2mH 500µF 16mH 250µF
100 3.1mH 800µF 6.2mH 400µF 12mH 200µF
130 2.4mH 600µF 4.7mH 300µF 10mH 150µF
200 1.6mH 400µF 3.3mH 200µF 6.8mH 100µF
260 1.2mH 300µF 2.4mH 150µF 4.7mH 75µF
400 .8mH 200µF 1.6mH 100µF 3.3mH 50µF
600 .5mH 136µF 1.0mH 68µF 2.0mH 33µF
800 .41mH 100µF .82mH 50µF 1.6mH 26µF
1000 .31mH 78µF .62mH 39µF 1.2mH 20µF
1200 .25mH 66µF .51mH 33µF 1.0mH 16µF
1800 .16mH 44µF .33mH 22µF .68mH 10µF
4000 .08mH 20µF .16mH 10µF .33mH 5µF
6000 51mH 14µF .10mH 6.8µF .20mH 3.3µF
9000 34mH 9.5µF 68mH 4.7µF .15mH 2.2µF
12000 25mH 6.6µF 51mH 3.3µF 100mH 1.6µF
Freq.
Hertz
Speaker Impedance
2 OHMS 8 OHMS 4 OHMS
L L L C C C
6dB/Octave Low-Pass 6dB/Octave High-Pass
L C
L = Low-Pass (Inductor)
C = High-Pass (Capacitor)
For more information, see your Authorized Rockford
Fosgate Dealer.
!