Hello,

I have a Z2 in my 07 corvette, the original owner had wired it incorrectly and ran the speaker level outs into the GMCO adapter which then goes on to the factory amp.

I re-connected the RCA's to the GMCO box and hooked them up to the Z2, I was getting a bad shut off pop sound so I put in a couple ground loop isolators which fixed that.

Now I still have a little alternator whine in the speakers.

I've tried to ground the RCA's to the pioneer chassis, and tried a temp wire right to the battery (-), whine got much worse.

I tried grounding the pioneer chassis to the alternator, still worse.

I connected that temp wire to the main ground for everything on the HU side of the system, same thing, MORE whine.

I've read some folks have used a line level convertor box to get around this, but wanted to get some input before I do that to see if anyone has some other ideas.

Thanks for looking!

I forgot to mention I do have the unit bypassed.

you way need to come speaker level out of the head to a LOC then to the GMCO.

Use the pots on the LOC to adjust

you might be getting to little signal to the amp.

you way need to come speaker level out of the head to a LOC then to the GMCO.

 

Use the pots on the LOC to adjust

 

you might be getting to little signal to the amp.

Possibly but the whine is constant and independant of HU volume so I don't know.

You may have to ground your entire system from the same ground source. If your factory sub amp or radio is grounded from two different places, then you may get a frequency difference causing the radio noise.

I had this problem as well. Ultimately the only fix was to bypass the external amp and use the one in the z1/2/3. Tried many other solutions without success.

this has been covered before and verified that it does in fact eliminate all hissing, buzzing, whining or any other sound not normal for stereos.

This is what was emailed to me from Memphis techs and it worked for me:

What we were suggesting was:

Tap off from the 12v power lead (constant power) and the ground <<<<

and run those wires back to the head unit. Since the remote turn on lead is going in the opposite direction (coming

from the head unit to the amp), take it and twist it around the 12v and ground coming from the amp back to the head unit.

The purpose of this technique is two fold;

it allows your head unit and amp to theoretically MATCH the 12v constant and the ground.

And since you're twisting those wires back to the head unit around the remote turn on, it helps cancel noise as well.

So, just to clarify- your head unit will no longer be connected to 12v constand and ground in the radio harness:

it will get it's 12v constant and ground directly from the amp. And since the remote turn on is running the same path

as those wires will be running, it's a good idea to twist them (or braid them) around one another.

If none of the above work try this:

at the back of the radio, in the RCA harness, find any RCA ground (should be a thin black wire leading to the RCA plug itself) there are probaly 4 of them.

carefully strip that black insulation back and tap your temp wire to the RCA ground, touch the other end to the chassis of the radio.

you should probalby only need 8 inches of wire.

this could possible eliminate your turn on pop, as well. going through a ground loop isolator is a last resort, for it is degrading sound quality, as well as voltage. like putting a bandaid on a knife wound.

Pioneer's with the RCA plug (RCAs not interannly connected to the unit) have a gounding issue resulting in gain mismatch (ground loop)

good Luck

Wolfz23