Rockford Fosgate PUNCH 4020 DSM - Manual (Page 15)

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U
S I N G T H E
XC
ARD
The crossover functions are controlled through the use of an
XCard and can be set for high-pass, low-pass or full range
operation. These cards are shipped in the most common fre-
quency. Each crossover card has two faces: one face operates Full
Range, the other has arrows to indicate the edge for selecting HP
(high-pass) or LP (low-pass) operation. Orient the card with the
desired operating edge, indicated by the arrow, toward the socket
terminals inside the amplifier. Firmly, but carefully, plug the card
into the socket.
Low Pass Full Range High Pass
FULL ↕
HP
➝
➝
LP
HP
➝
➝
LP
The crossover point can be altered by changing the resistor value.
Use the following formula to select the appropriate resistor value
to be placed on the XCard.
3386
fo
= R (in k
Ω
) for .047
µ
f cap
= R (in k
Ω
) for .022
µ
f cap
7234
fo
Where: R =
Ω
fo = desired crossover frequency
c = capacitor in farads
ex: .047 x 10-6 for .047mf cap
Crossover Card
High Pass
Low Pass
Full Range
R1 R2 R1 R2
FULL
The actual formula is:
R =
1
2
π
foc