AudioControl Epicenter 1200, Installation Manual

Page: 17 / 36

17
Speaker Connections
Establish a standard connection color code and stick with it. One
conductor of the speaker wire is normally marked by a different color
(silver versus copper) or there is a ribbing on one side. Typically this
marked conductor is used for the positive (+) speaker leads. Really
good wire has Positive and Negative printed right onto the wire
jacket.
Match the polarity markings on the unit with the polarity markings
on your speakers.
Speaker and Wiring Impedance
Speaker impedance often is and should be straight forward. Speakers,
like other resistors, if wired in parallel “show” lower values than the
individual components. Here are two examples for calculating speak-
ers wired in parallel:
Calculating Impedance
For three 8 Ohm speakers wired in parallel (pluses connected to
pluses) the impedance is 1/8 + 1/8 + 1/8 = 3/8
Then take the inverse or 8/3 =
2.66 Ω
For two 8 Ohm speakers wired in parallel (pluses connected to
pluses) the impedance is 1/8 + 1/8 = 2/8
Then take the inverse or 8/2 =
4 Ω
Often the real world is more complicated than theory, and for speak-
ers this is the case. An eight Ohm speaker is not eight Ohms at all
frequencies. Plus passive crossover networks add their own changing
conditions. Be aware of speakers that have significant dips from “nom-
inal” values in portions of their frequency range, and speakers that are
rated at unusual impedances, for example 3.5 Ohms. The Epicenter is
tolerant of lower impedance loads down to 1 Ohm, however, all good
designs use some margin of error.
Your choice of speaker wire gauge and the length of the runs, also
affects the speaker impedance load presented to the amplifiers. Even
fairly short speaker runs can have significant resistance if you use a
smaller wire gauge. This can be a benefit if you are paralleling lots of
speakers. The wire itself acts as an impedance limiter, since the ampli-
fier cannot see a speaker load lower than the resistance of the wire.
The downside of this wire resistance is that you waste some part of
the total power available to the speakers.
Chapter 4: Installation