Rockford Fosgate PWR-810 - Manual (Page 6)

after the amplifier and separates the signal fed to each speaker in the
system. Active crossovers offer the accuracy and flexibility needed for
a sophisticated system and are used in complex multiple amp designs.
Passive crossovers (capacitors and inductors) allow the use of mul-
tiple speakers in a simple system which can easily be expanded over
time. We recommend using a 6dB per octave, 100Hz low-pass
crossover for the Punch Power Woofers when used with a passive
system.
To customize the installation, try adjusting the crossover point one
octave up or down to optimize the system staging.
3
C
A L C U L AT I N G
L
O A D
I
M P E D A N C E
The Punch Power Woofers are used for the sub-bass region, those
frequencies below 100Hz. This is the foundation for the music and
the frequency range you feel. Before selecting the passive crossover
it is necessary to calculate the load impedance of the speaker system.
In a series circuit the impedance is determined by the formula:
R
t
= R
1
+ R
2
+ R
3
+ etc.
In a parallel circuit the impedance is determined by the formula:
1 1 1 1 1
R
t
R
1
R
2
R
3
R
4
Where R
t
is the total speaker load and R
1
, R
2
, etc. represent each
speaker in the system.
The crossover is connected in line to the positive terminal of the
speaker system. The crossovers are available from Authorized Rock-
ford Fosgate Dealers.
= + + + + etc.