Galaxy Audio G-1200, User Manual, Page: 7 / 16

SOUND REINFORCEMENT BASICS
The SPEAKER OUTPUT jacks on the G-Series amps are designed to power up to two
Core (or other brand) 8 ohm speakers, or up to four Hot Spot 16ohm speakers per channel.
Most professional-type speakers (like the Core and Hot Spot) have two jacks which are
wired in parallel (meaning the signal can travel into one jack and out of the other). Think of
each speaker as a “load” added to the amplifier, the greater the number of speakers, the
heavier the load. Adding too many speakers can overload the amplifier, causing it to
overheat and distort. This will not only sound bad but it can damage the amplifier, the
speakers, or both.
One easy way to determine the load on the amplifier is to use Ohm's law, which states:
“The total impedance of N speakers in parallel is equal to the reciprocal of the sum of the
reciprocals. In equation form:
Where Z1 is the impedance (or ohm rating) for the first speaker, Z2 is the impedance for
the second, and so on for every speaker in the chain. This equation calculates the total
impedance of the speaker system, which should
NOT be lower than the minimum
impedance rating of the amplifier.
The G-Series amps are rated for loads as low as 4 ohms per channel. Therefore, the total
impedance of the speaker system must be greater than, or equal to, 4 ohms. Anything less
will overload the amplifier. For one pair of speakers use the short form of the equation: the
product of the two speakers divided by the sum of the two speakers is equal to the total
impedance or the equivalent impedance of the speaker system.
This equation may be used to calculate the equivalent impedance for additional speakers in
two-speaker increments. Determine the impedance of the first two speakers, substitute Z
total for Z , and include the next speaker. Repeat the process until all speakers have been
included. The result should be the same as with the first method. A word of caution: polarity
rules must be observed when connecting multiple speakers. Polarity will not affect the Z,
but can affect the quality and volume of the sound. If you are having problems with any of
these applications use Galaxy Audio's CRICKET Polarity and Continuity Test Set to check
the polarity of your cables.
OHM’S LAW
and the G-Series Amps
Z(Total)=
1
1 1 1 1 1
___ ___ ___ ___ ___
+ + + +
Z Z Z Z Z
1 2 3 4 N
Z=
Z x Z
1 2
Z + Z
1 2
3