In Reply to: speaker impedance question posted by troutboy on October 23, 2008 at 08:24:41:
I am not an expoert but I can tell you a little bit.
For almost all speakers impedance doesn't vary with volume but it does vary with frequency due to the effects of inductance and capacitance within the speaker. The variation is usually fairly complex and can't be adequately defined by one one or two impedance values.
An 8 ohm impedance rating might mean that the impedance averages about 8 ohms but it tells you nothing about how the impedance varies with frequency.
The minimum impedance is what is usually more significant than the average in its demands on the amp because the lower the impedance, the more current the amp has to deliver to provide the same power. All else being equal, the more current an amp has to deliver, the more it costs.
The second impedance number might be the minimum impedance. This would be useful information but the frequency it occurs at and the phase angle are also important.
David
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Follow Ups
- Impedance generally varies with frequency - energyandair 10/23/0820:06:54 10/23/08 (0)