Rockford Fosgate S1-408 - Manual (Page 6)

C
ALCULATING
L
OAD
I
MPEDANCE
The Series 1 Woofers are used for the sub-bass region, those frequen-
cies 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
…
In a parallel circuit the impedance is determined by the formula:
R
T
R
1
+ R
2
+ R
3
…
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.
3
1 1 1 1
C
ALCULATING
V
OLUME
Calculating volume is merely a matter of measuring the dimensions
in inches and using the formula: Volume = Height x Width x Depth.
The result is in cubic inches. Convert this to cubic feet by dividing by
1,728 (the number of cubic inches in a cubic foot). If two facing sides
are of uneven length, add them together and divide by two to get the
average. Using this number will give you the volume without the
necessity of calculating the box in sections and adding the sections
together. The thickness of the baffle material determines the internal
volume. The speaker itself also reduces the internal volume. The
amount of air displaced by each model is listed on the specification
sheet and should also be subtracted from the gross volume calcula-
tion.
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