hi peoples im in a bit of trouble i hooked up some speakers to a amp and when the car is running it makes a screaming noise does anyone know what has happened

let the installer out of the boot and all should be fine......

OR, (and more likely)

You probably ran the RCA and/or speaker leads next to the power cables for the amp..that will do it every time, and may be on top you used cheap non shielded cables....

Give some more info... Are you running amps? What does the sound actually sound like? Does it change with revs? Did it just start or has it been doing it since install? Anything else you think might help us...

All answered in the first post

Ahhhh...just realised you drive a commodore that would explain it

Another common cause that isnt related to the signal cables is due to the quality of the grounding and whether or not a ground loop is occuring ... rather than writing this down yet again as its a common issue - do a search for ground or whining noises within this forum .. been done plenty of times.

Might look at doing some sort of FYI thread/doco on these sorts of problems

no its not the installer i let him out a while ago
yes the noise does change with the revs
even if the head unit is disconnected but the amps are on it does it so it must be something around the amps.
on the 4 channel amp if i leave 1 set of rca leads connected and the other set not, it doesnt make the noise

Check everything is earthed correctly, the whining is the altenator charging system....inline noise filters help but should be a last resort

as xb-coupe-351 has said make sure all ground points have clear contact - as in file paint etc away so its bare metal to metal contact ... the bigger the terminal connections the better (due to the surface area allowing better contact and faster current transfer) if your using ring terminals etc.

Ensure your negative/earth cabling is the same size/guage or larger than the power/positive wiring.

Try to have all your gear mount to as minimal ground points as possible to try and eliminate ground looping ... so if all your sub amplifiers are located in the same spot .. then mount both amps negative terminal to the same ground location instead of a seperate point each.

Other wise try an noise or inline noise filter on the main power wire.

If after checking all the earthing points and are sure you have decent enough cabling for power/earth and signal cables and that the signal cables are clear from your power cabling then might be worth consulting a car audio shop n get em to take a squiz for you.

You missed one... Does it change with the revs? No need to be a wanker, was only trying to help.