Speaker And Wiring Impedance - AudioControl SAVOY G4 Installation Manual

Speaker and Wiring Impedance

Speakers, like other resistors, when wired
in parallel "show" lower values than the
individual components. Here are two
examples for calculating speakers 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 speakers 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
"nominal" values in portions of their
Speaker Wire Resistance:
Wire Gauge versus Run Length
Wire Gauge
24 GA
22 GA
20 GA
18 GA
16 GA
14 GA
12 GA
Run Length
25' 50'
1.3Ω 2.6Ω
0.8Ω 1.6Ω
0.5Ω 1.0Ω
0.3Ω 0.6Ω
0.2Ω 0.4Ω
0.1Ω 0.25Ω
0.08Ω 0.16Ω
Speaker and Wiring Impedance
frequency range, and speakers that are
rated at unusual impedances, for example
3.5 Ohms. The Savoy G4 is tolerant of
lower impedance loads, 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. As you can see in this table,
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 amplifier 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.
100' 250'
5.1Ω 12.8Ω
3.24Ω 8.1Ω
2.0Ω 5.0Ω
1.28Ω 3.2Ω
0.8Ω 2.0Ω
0.5Ω 1.26Ω
0.32Ω 0.8Ω
500'
25.7Ω
16.0Ω
10.1Ω
6.4Ω
4.0Ω
2.5Ω
1.6Ω
S G4
AVOY
Installation Manual
13