I
NSTALLATION
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
!
stereo and 4Ω bridged.
L
6dB/Octave Low-Pass
C
6dB/Octave High-Pass
L = Low-Pass (Inductor)
C = High-Pass (Capacitor)
For more information, see your
Authorized Rockford Fosgate Dealer.
O
PERATION
ADJUSTING GAIN
Do the following individually for each channel.
To adjust the gain setting, turn the amplifier gains all the way down. Turn the source unit volume up
until distortion is audible and then turn it down a bit until the distortion is inaudible. This will be
about two thirds all the way up on most source units. Next, turn the amplifier gain setting until once
again distortion is audible and then back it down until the distortion is inaudible. Rockford Fosgate
source units do not distort, so the volume can be used at maximum setting.
NOTE: For a more in depth setting procedure, contact Rockford Technical Support.
10
Speaker Impedance
Freq.
2 OHMS
Hertz
L
C
80
4.1mH 1000µF
100
3.1mH
800µF
130
2.4mH
600µF
200
1.6mH
400µF
260
1.2mH
300µF
400
.8mH
200µF
600
.5mH
136µF
800
.41mH
100µF
1000
.31mH
78µF
1200
.25mH
66µF
1800
.16mH
44µF
4000
.08mH
20µF
6000
51mH
14µF
9000
34mH
9.5µF
12000
25mH
6.6µF
4 OHMS
L
C
L
8.2mH
500µF
16mH
6.2mH
400µF
12mH
4.7mH
300µF
10mH
3.3mH
200µF
6.8mH
2.4mH
150µF
4.7mH
1.6mH
100µF
3.3mH
1.0mH
68µF
2.0mH
.82mH
50µF
1.6mH
.62mH
39µF
1.2mH
.51mH
33µF
1.0mH
.33mH
22µF
.68mH
.16mH
10µF
.33mH
.10mH
6.8µF
.20mH
68mH
4.7µF
.15mH
51mH
3.3µF 100mH
8 OHMS
C
250µF
200µF
150µF
100µF
75µF
50µF
33µF
26µF
20µF
16µF
10µF
5µF
3.3µF
2.2µF
1.6µF