Rockford Fosgate 351M Installation Et Fonctionnement page 7

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