Speaker Resistance ?

[Bob]

Hello,

Not an E.E., so please bear with me a bit.

Have a 2" dia speaker in kid's toy.
Seem like it doesn't work, but hard to get to, to verify.

It says 8 ohms.

I imagine that this is the Z, and not the dc resistance; correct ?

a. What might be a "typical" dc resistance for a
really small (2") speaker like this ?

b. Can't get a really good look at it, as it is really embedded.
It might be more of an electrostatic type of speaker, than the typical
moving coil type.

How would your answers for (a) change, if this is so ?

Thanks,
Bob

 

[Rich.]

8 ohms is 8 ohms. If you were to completely disconnect the speaker and
connect an ohmmeter across it's leads, the ohmmeter would read 8 ohms.

 

[Rich.]

Even though I could not understand the OP, I do understand that you are
WRONG! Ideally, the speaker voice coil would have a resistance of ZERO.
Unfortunately, it is impossible to manufacture such voice coils short of
having superconductivity. The impedance of the voice coil is ideally
found by applying am ac signal voltage V, measuring the resulting
current flow I and finding the impedance Z = V/I using complex numbers.
The applied V is countered by a back emf so that Z is not equal to the
measured resistance of the voice coil.

Really? Did you even try measuring the resistance of an 8 ohm speaker before
say that it won't measure 8 ohms?

 

[Andrew Gabriel]

Hello,

Not an E.E., so please bear with me a bit.

Have a 2" dia speaker in kid's toy.
Seem like it doesn't work, but hard to get to, to verify.

It says 8 ohms.

I imagine that this is the Z, and not the dc resistance; correct ?

a. What might be a "typical" dc resistance for a
really small (2") speaker like this ?

Probably about 3/4 - 7/8th of the impedance.
For a higher power speaker, the resistance will be
significantly lower.

b. Can't get a really good look at it, as it is really embedded.
It might be more of an electrostatic type of speaker, than the typical
moving coil type.

How would your answers for (a) change, if this is so ?

A passive electrostatic speaker is capacitive, but they are
normally used for higher frequences only, together with a
coil speaker for the lower frequencies.

 

[Tom Biasi]

Hello,

Not an E.E., so please bear with me a bit.

Have a 2" dia speaker in kid's toy.
Seem like it doesn't work, but hard to get to, to verify.

It says 8 ohms.

I imagine that this is the Z, and not the dc resistance; correct ?

a. What might be a "typical" dc resistance for a
really small (2") speaker like this ?

b. Can't get a really good look at it, as it is really embedded.
It might be more of an electrostatic type of speaker, than the typical
moving coil type.

How would your answers for (a) change, if this is so ?

Thanks,
Bob

Hi Bob,
If it says 8 ohms on it,it is most likely just a cheap speaker you could
get at rat shack in several diameters.
Not sure what you mean by "Seem like it doesn't work "
Does sound come out of it or not?
The speaker is not the only thing responsible for the sound.
It's also down on the list of failures on such products.

Tom

 

[F Murtz]

Hello,

Not an E.E., so please bear with me a bit.

Have a 2" dia speaker in kid's toy.
Seem like it doesn't work, but hard to get to, to verify.

It says 8 ohms.

I imagine that this is the Z, and not the dc resistance; correct ?

a. What might be a "typical" dc resistance for a
really small (2") speaker like this ?

b. Can't get a really good look at it, as it is really embedded.
It might be more of an electrostatic type of speaker, than the typical
moving coil type.

How would your answers for (a) change, if this is so ?

Thanks,
Bob

If the reason for this discussion is to see if it works, just put a 1.5
v battery across it intermittently and see if it crackles.