Just finished connecting radio and amp. When I bought the car the rear speakers ground wire was grounded in the truck and only the positive side is inside the car..when I turn off the car and back on the rear speakers don't come back on but if I disconnect the positive side and reconnect they come on..is that because the ground is in the truck and not to the amp..the speakers are 6x9 Jensens

 

Are you running an aftermarket radio/amp with the 6x9's or a factory radio. What year car are we talking about?

 

After market radio and amp..74 Cutlass Supreme...they play fine once I disconnect then reconnect the wire...car battery low do you think that would have something to do with it

 

You have to run low power wires from the radio to the amp (usually RCA jack cables), and then pos/neg pair of wires from the amp to the speakers. They have to be isolated from chassis ground. There should be an output B+(12v) that will power the amp on and off with the radio.

 

Yes I have the rca cables will try the speaker wire

 

The original GM stereos of the mid-seventies used the chassis ground as the common for the rear speakers.

A modern aftermarket stereo or amd DOES NOT.

Using ground for the speaker common will destroy your amplifier, unless its protective circuits know enough to switch it off.

- Eric

 

^^^^this!

 

Thx so much

 

If the speakers are connected to a low power radio of the 6 Watt per channel variety the output is common ground and the speakers can be grounded in the trunck as the OP's are. If the head unit is a high power, 20 Watt per channel output type the grounded speakers can cause problems and possibly burn out the amplifier chip. It sounds like you may have had the previous installation type originally and then an amplifier was added later.

EVERYTHING in this scenario depends on the amplifier. Some high quality amplifiers are common ground, but if the speaker output negative(-) wires connect to ground it will cause terrible engine noise. If the positive (+) lead of the amp shorts to chassis ground it should go into protect mode and shut off until the short is corrected. Cheaper amplifiers without protection circuitry will die! If you are lucky they will blow the fuse the first time. Balanced Transformer-less or BTL amplifiers use a push-pull amplifier system and if they are shorted on either the positive or negative lead they will go into protect mode if higher quality or if of the less expensive variety, burn out.

It is always best to have the + and - leads of the speaker run on isolated speaker wires and connected directly to the amplifier.

 

Thx all ran the - side to the speaker and all is good

 

Glad it works correctly now.