Determining PC Speaker Polarity

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I have a set of computer speakers that did not come with an adapter. I need to determine the polarity of the pin on the power jack of the speakers so I know what adapter I can use. Does anyone know how I can determine the polarity of the speakers?

And yes, I have tried contacting the manufacturer of the speakers as well as searching the internet. There is no information available on the speakers or what adapters are needed. The speakers don't indicate the polarity. They only indicate what voltage adapter to use.

Hmm, tricky.
I assume this is the coaxial style of connector? There doesn't seem to be a standard polarity: I just picked up two adapters and one has the centre pin positive and the other, negative.
You might get some clues by looking at any similar speakers from the same manufacturer, in the hope they've settled for one polarity throughout their range (assuming they even bother with such details on a website).
Otherwise, the surest way is to take them apart and check out the circuitry - but this assumes (a) they're not some moulded-shut case and (b) you know what to look for.

If they're cheap speakers you can just try it both ways and hope there is a diode to protect against polarity reversal. If you don't want to do that, the only real way to tell would be to open them up, as Cornflake suggested. Look for an IC, look up its pinout on the internet, and trace the ground pin back to the negative. Or if you can find a bipolar transistor, you can trace the emitter to negative for NPN or collector to negative for PNP.

^^ Plus, decoupling capacitors: the polarity of one or more should be fairly easy to trace back to indicate the positive input.
Hopefully there is a protection diode, and I've seen some devices using a FW rectifier on the power input so the polarity doesn't matter at all for those types.

Generally, the outer conductor is "-" and the center conductor is "+".

"-" is also called "common", "ground", "minus", "negative", or "-V".

"+" is also called "plus", "supply", or "+V". Sometimes it is even labelled with the voltage rating. (i.e., "+12Vdc")

HOWEVER, I can not guaranty that the foregoing is true for your speakers, so PROCEED AT YOUR OWN RISK!! !

Sony seem to use -ve on the inner conductor - at least they do on the two Sony power adapters I have here.
Where are standards when they're needed?

Try a multimeter, and set to Ohms or continuity, and probe the speaker input with these leads. If infinite in Ohms then the current is blocked, switch leads around and check Ohms again. If lower then that is the direction of the current. The thing here is knowing the output polarity on your multi meter - in continuity mode. To be sure, you would need another Ohm meter to know. It could be in the reverse to the color of the leads.

A thought.

I had the same problem once with some wireless headphones (sony rf). Just tried the adaptor at both polaritys, headphones were fine.

Doesn't make it any easier for you though

Unless you have the product model/code. Search math can work wonders.