Speaker Impedance

How does speaker impedance work?
I'm not thinking HiFi here, although it may be the same. I'm thinking just the basic small speaker you'd get from an electronics store.

There's a lot on the web, but it's all about connecting amps, etc, which is not quite what I'm looking for


Thanks

mark_3094 said:

How does speaker impedance work?
I'm not thinking HiFi here, although it may be the same. I'm thinking just the basic small speaker you'd get from an electronics store.

There's a lot on the web, but it's all about connecting amps, etc, which is not quite what I'm looking for


Thanks

Click to expand...

How does it work? Do you mean what determines a speaker's impedance? If so it's value is determined primarily by the resistance and inductance of it's voice coil winding. It is generally a nominal value as a speaker is called on to be able to respond to a wide range of frequencies and it's impedance will not be perfectly constant over that range. Impedance is sometimes referred to as AC resistance by some.

Lefty

A speaker resonates at a low frequency which increases its impedance from 8 ohms to 40 ohms. Then above the resonance frequency its impedance is 8 ohms. Its resistance is about 7 ohms.
As the frequency increases the inductance of the speaker's coil causes the impedance to rise. Some speakers also resonate at high frequencies.

A modern audio amplifier has an extremely low output impedance of 0.04 ohms or less which damps the resonances of a speaker.

Mind you none of these rules apply to all speakers. I cannibalize parts from pretty much every electronics device anyone I know throws up (I have quiet a collection) one thing I can tell you is the impedance (DC resistance) of these speakers are ALL over the place, 4 8 16 and 32. The smaller the speaker generally speaking the higher the impedance, I think most of the headphones I have are in the 16-32 range. The couple speakers I have that put out a few watts are 4ohm. The physical shape of the speaker will determine at what frequency/frequencies it resonates at, the enclosure matters too.

The speakers in my car are 2 ohms. Then their current is twice as much as 4 ohm speakers which makes their max power twice as much as 4 ohm speakers.

Only if the amp can drive it.