A
andrew_h
- Jan 1, 1970
- 0
Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
andrew_h said:Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
andrew_h said:Some of the 'tutorials' and 'faqs' on the net are unneccessarily
complex.
Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
its the same as it would be if you wereandrew_h said:Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
P.S.andrew_h said:Can someone explain to me exactly what speaker impedance is?
Also, Why is it only 4, 8, etc. ohm? (such even numbers).
Bob Masta said:First of all, instead of "impedance" think "AC resistance".
It's the value you would use when you are trying to compute
the power the speaker will draw from the amp, via V^2/Z
where V is the RMS output voltage and Z is the impedance.
(Note that the power drawn by the speaker is not the
same as the sound power delivered, since speakers
have a wide range of efficiencies... but 1% is typical.)
In a speaker, impedance is made up of the DC resistance
of the copper wire in the voice coil, plus the AC "reactance"
of the inductive effects from that same wire being in the
form of a coil (with an iron core), plus the mechanical
reactance due to the spring in the suspension and the
mass of the moving cone. The reactance part varies
with frequency, and actual speaker impedance typically
has a big peak around resonance, or two peaks one
on either side for tuned designs (like those with ports
or passive drivers).
So, the numbers like "4 ohms", "8 ohms", etc are
really just nominal values. Their main real use is
in comparing suitability of drivers for use with a
particular amp. Higher impedances demand less
current from the amp to get a certain power, so
amps are typically rated as to the lowest nominal impedance
they are happy to drive. Lower impedance may
draw too much current, but you can always use
a higher impedance speaker... at least with modern
solid state amps. Tube-type amps with output
transformers typically have different taps for driving
different speaker impedances, and there you
should select the matching value.
Best regards,
Bob Masta
dqatechATdaqartaDOTcom
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator
I have....is confusing.