cable problem

[cheyworth]

my parents have a 2 room setup, with in wall speaker cables, after doing some decorating they are unsure which cable is + and which is -. is there an easy way to test them and make sure the speakers are wired correctly.

Chris

 

[fatboyslimfast]

The easiest way is to connect them, then play music through them and stand in front of them.

Then get someone to turn the balance control hard to one side.

If the bass level stays the same, they are wired correctly. If it increases noticeably, then one side is different to the other. Change 1 speaker's connections...

Whilst it will make a slight difference if they are both reversed rather than correct, it's more important to ensure that they are both the same way..

 

[Anonymous]

You don't say how the wires are terminated.

Are there plates on the wall with sockets in them or do the wires just run in the wall?

Assuming it's the former then you need 2 speaker plugs a long length of wire a battery and a bulb - a torch will do. You can make a continuity tester with this. Form a circuit that connects long wire to battery to bulb to short wire. Put a speaker plug on each end.

Now plug one plug onto the master socket and then plug into each slave socket in turn. When the bilb lights you know what's connected to what.

Alternatively by a cheap multi-meter in Maplins and make a long flying lead from bell wire. and you can do the same job.

 

[cheyworth]

can i just add an LED to the speaker circuit if it lights or not then i know?

Chris

 

[Dave_]

afaik led's are directional, so you'd have to make sure its the right way round polarity wise, but dont see why not

 

[cheyworth]

if it's the wrong way round 'no sound'?

 

[JoelSim]

Aren't they black or red? Or marked in another way at the amp end?

ÿ

ÿ

 

[Andrew Everard]

Or you could try connecting a battery to the cable at the amp end, and hooking up the speakers at the speaker end. Connect the amp end - terminal to the - terminal of the battery and hook up the speakers, then with someone watching at the speaker end, touch the + cable at the amp end onto the + terminal on the battery.

If the speaker bass cone moves outward, you have the cable connected correctly to the speaker. If the cone moves inward, you have the speaker connected in reverse.

So now you know which + and - conductor at the amp end corresponds to which + and - at the speaker end, and problem is solved.

Just about any battery will do, but I've often done this with something like a 9V PP3/6LR61/1604A as this gives a very obvious speaker driver movement, which you may not get with a more common 1.5V battery.

 

[JoelSim]

Andrew Everard:

Or you could try connecting a battery to the cable at the amp end, and hooking up the speakers at the speaker end. Connect the amp end - terminal to the - terminal of the battery and hook up the speakers, then with someone watching at the speaker end, touch the + cable at the amp end onto the + terminal on the battery.

If the speaker bass cone moves outward, you have the cable connected correctly to the speaker. If the cone moves inward, you have the speaker connected in
reverse.

So now you know which + and - conductor at the amp end corresponds to which + and - at the speaker end, and problem is solved.

Just about any battery will do, but I've often done this with something like a 9V PP3/6LR61/1604A as this gives a very obvious speaker driver movement, which you may not get with a more common 1.5V battery.

Interesting

 

[the record spot]

Andrew Everard:
Or you could try connecting a battery to the cable at the amp end, and hooking up the speakers at the speaker end. Connect the amp end - terminal to the - terminal of the battery and hook up the speakers, then with someone watching at the speaker end, touch the + cable at the amp end onto the + terminal on the battery.

If the speaker bass cone moves outward, you have the cable connected correctly to the speaker. If the cone moves inward, you have the speaker connected in reverse.

So now you know which + and - conductor at the amp end corresponds to which + and - at the speaker end, and problem is solved.

Just about any battery will do, but I've often done this with something like a 9V PP3/6LR61/1604A as this gives a very obvious speaker driver movement, which you may not get with a more common 1.5V battery.

Clever clogs!