tried another earth point (the rear strut brace bolts) and exactly the same.

i know install manuals say not to put speaker ground to chassis, and to run it back to amp, but would it be worth putting the amp speaker outputs - to ground and see where that takes me?

im going to pop in a test speaker again, and see where that leads me. then try removing the Xover in each door.

update: no go with test speaker. identical problem. also bought a GLI and it seems to make problem worse!! im wondering if i've got a bad RCA cable.

 

It's not a bad RCA cable. And attaching your amp output to ground isn't good for your amplifier, lol

You really need to get a multimeter and ohm it out. I'm willing to bet there's a 4ohm difference. As such, you can run with it that way (as I currently am), or you can reground the cabin to the neg terminal and see if it makes a difference.

 

i've got an extra batt cable from battery chassis bolt > engine block
also a second cable from battery post > battery chassis bot.

i've ohm checked amp power terminal earth > chassis earth - and at most it's 1ohm.

i've just done:
ipod w/RCA > amp > test speaker and still the same noise so i've narrowed it down to power cable issues/earth issues, or the amp itself.
so far with 3 different earth points tried for the amp, it's all proven to be the same, i'm thinking it's the amp.

with the amp unpowered and RCA's disconnected, i have no continuity between amp RCA and amp ground. (RCA's grounded ok at HU end) - is that right?

 

I honestly don't know about amp RCA to amp gnd, I'd have to check. Give me a day or two to get back to you on it.

 

na, bit pointless now neut... it's not that side of things.

i've swaped HU+RCA for an Ipod, and car speakers+wiring for a test speaker and it's still noisy.

looking like 1 of 2 things left.
power cables to amp
amp itself.

i've got some battery cable coming at weekend, so i can put ground direct to battery. can also have a play with the 12v line aswell.

not having much luck at all!!