1 watt 8ohm speaker inductance

[Sceadwian]

I'm trying to come up with an approximate inductance value to use for a 1 watt 8ohm coil resistance small cone speaker, basically the kind you yank out of cheap radios. I don't have any way of measuring the inductance though, can anyone give me a ballpark figure to use?

Edit: The only refrence to a measured static inductance I've found so far is 560uH

 

[Nigel Goodwin]

Why would you want to know?, it's not really of much use as it doesn't act like an inductor.

 

[Sceadwian]

Was trying for a quick and dirty way of getting a better simulation of a speaker aside from an resistor. Never mind though I found a decent spice model that simulates the physical properties of a speaker that's not too bad.

 

[Styx]

you can't just treat a speaker as an inductor.
a basic rep would be a resistor, if you are starting to want a more detailed model you have to include variable inductance and such... not worth the hassle unless a pro

 

[stevez]

A number of years ago I read a magazine article about speaker enclosures, amplifiers and other audio system components. I was left with the impression that the reactance of the speaker was related to the frequency - and the physical characteristics of the enclosure that changes the way a speaker behaves (as compared to open-air).

The whole point of the article was to explain that the enclosure/speaker pair - and amplifier can be matched or mis-matched in terms of frequency response. The reactance differences across the spectrum were not trivial. Sometimes the differences offset other characteristics - other times it compounded a problem. I distinctly recall the author explaining how applying pressure with a fingertip to the cone would significantly affect reactance as they swept the audio range. It appeared that the author did a lot of measuring and analyzing.

Not sure if this helps but thought I'd offer just in case.

 

[Nigel Goodwin]

Was trying for a quick and dirty way of getting a better simulation of a speaker aside from an resistor. Never mind though I found a decent spice model that simulates the physical properties of a speaker that's not too bad.

A resistor is probably as helpful as anything else?, unless you can find an exact spice model for the speaker and cabinet you're using - but an inductor would be no use at all.

 

[JimB]

Some years ago I needed to find the impedance of a cheap unknown speaker.
Cutting a long story short, the speaker was 3ohm and within my measurment accuracy was resistive from 20 to 1000hz.

JimB

 

[Nigel Goodwin]

Some years ago I needed to find the impedance of a cheap unknown speaker.
Cutting a long story short, the speaker was 3ohm and within my measurment accuracy was resistive from 20 to 1000hz.

Easier to just measure it's DC resistance? - it's about 75% of the impedance, and is plenty accurate enough at that. Interesting you didn't get a peak within that range though!.

 

[Sceadwian]

I want to feed simulated amplifier output into a simulated speaker to see what kind of results I can expect. It's just a learning exercise for understanding more complex circuits in spice than just a few basic bits glued together real fast. I'm not used to dealing with complex electromechanical systems and I'm learning on my own. After viewing the schematic I understand it a little bit more, there's a few increasing resistor values right off the bat fed into a parallel array of inductors to give a variable inductance for the voice coil. A couple parasitic capacitors that simulate the actual physical feedback from the cone mass.
I found a schematic for LTspice on the Yahoo Groups forum for ltspice
It's attached if anyone wants to see it.