Using Passive Crossovers; Operation; Adjusting Gain - Rockford Fosgate PUNCH Pro Series Installation & Operation Manual

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