Speaker Impedance

[mark_3094]

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

 

[Leftyretro]

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

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

 

[audioguru]

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.

 

[Sceadwian]

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.

 

[audioguru]

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.

 

[Sceadwian]

Only if the amp can drive it.