Crown 2-650 - Manual (Page 13)

13
T y p i c a l a p p l i c a t i o n s . . .
c. Two amplifiers for stereo with a mono sub-bass
Here Two amplifiers are used with an active crossover to provide a separate sub-bass signal.
d. Calculating Impedance
Measured in ohms, impedance is a measure of AC resistance. Loudspeakers generally come in 16, 8 or 4
ohm varieties. Amplifiers have a lower limit to what impedance they can drive without being overloaded,
there is not usually an upper limit. The PULSE 2x650 can drive any impedance between an open circuit and
2 ohms when in stereo and between an open circuit and 4 ohms when bridged.
When more than 1 speaker is used, it is easy to calculate the total impedance but remember that unless
you are sure you know what you are doing, all the speakers should be the same impedance.
If the speakers are wired in series, just add their impedances together. If they are in parallel there is a
simple rule: two impedances the same will equal half the individual impedance, for example 8 & 8 = 4 or
to take this further, four 8 ohm drivers = 2 ohms (8 & 8 = 4 ..... 8 & 8 = 4 ..... 4 & 4 = 2).
L R
1
1
2
Sub speaker - 1300W 8 ohms
main (mid-high) speakers - 650W 4 ohms
Stereo
2
Bridge
2
1