Determining the impedance of a guitar cab?
- Thread starter amra
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mshilarious
Banned
Nope, that will tell you the DC resistance.
OK, more helpful answer, I just wanted to look at a speaker datasheet first. The DCR is normally less than the impedance. Also, impedance is nominal, if you look at a speaker's impedance graph, you'll see it wanders quite a lot sometimes. So the stated impedance is kinda an average. But if you have two speakers of similar type but different impedance to compare, the one with the higher DCR should have higher impedance.
However, you can't take a multimeter reading of say 5 ohms and say, hey this must be 4 ohms. It's probably 8.
punkin
Univalve & Avatar Speaks
What ms is getting at it resistive impedance vs. inductive.
I second the notion of looking at the back of the speakers and jotting down the notes on the backs of each of them and while you're at it, draw a simple diagram. Could be you've got a low watter in parallel with a high power monster...or worse yet,..they're in series and when the little guy goes, pop goes the amplifier.
After all, there's more to it than the load characteristics,...how much power can they handle is a good question too. In short, it's a good question you ask and you should get the whole picture while you're doing your homework.
Do this little exersize and we can then tell you exactly what's in your cab. Even a photo of the backside (guts exposed of course) would be helpfulf.
Peace
I second the notion of looking at the back of the speakers and jotting down the notes on the backs of each of them and while you're at it, draw a simple diagram. Could be you've got a low watter in parallel with a high power monster...or worse yet,..they're in series and when the little guy goes, pop goes the amplifier.
After all, there's more to it than the load characteristics,...how much power can they handle is a good question too. In short, it's a good question you ask and you should get the whole picture while you're doing your homework.
Do this little exersize and we can then tell you exactly what's in your cab. Even a photo of the backside (guts exposed of course) would be helpfulf.
Peace
amra
Well-known member
Thanks for the all the quick responses. There isn't one specific cab I was wondering about, but more about cabs in general. It would just be real sweet if you could figure the impedance of a cab nice and easy like that. I just had a feeling there would be more to it, than that.
I've tried and and gotten results that looked like they could be right, but just wasn't sure if it was something you could count on.
I've tried and and gotten results that looked like they could be right, but just wasn't sure if it was something you could count on.
crazydoc
Master Baiter
"Measuring speaker nominal impedance
If you just want to find out the nominal impedence of the speaker e.g. ist it 4, 8 or 15 ohms then there is a rough & ready way. Just use your multimeter to measure the DC resistance of the voice coil i.e. across the speaker terminals (with nothing else connected) and multiply the answer by 1.3. So if the DC resistance is say 6 ohms then the speaker is nominally 8 ohm impedance."
http://www.epanorama.net/documents/audio/speaker_impedance.html
There's more if you want to get into it a little. Unfortunately, impedance is an AC parameter, so it has to be tested with an AC signal, and is frequency dependent.
If you just want to find out the nominal impedence of the speaker e.g. ist it 4, 8 or 15 ohms then there is a rough & ready way. Just use your multimeter to measure the DC resistance of the voice coil i.e. across the speaker terminals (with nothing else connected) and multiply the answer by 1.3. So if the DC resistance is say 6 ohms then the speaker is nominally 8 ohm impedance."
http://www.epanorama.net/documents/audio/speaker_impedance.html
There's more if you want to get into it a little. Unfortunately, impedance is an AC parameter, so it has to be tested with an AC signal, and is frequency dependent.