[jonywalker]

I replaced the OEM-amp completely with PDX-4.100 and JL Audio Slash 300/2, where the PDX is used to drive Mid and High channels, and the JL Slash the sub-channels. I know it is a little strange combination with class D and class AB, but because of the small size of PDX I did a super OEM-look installation, and the sound quility of this combination is excellent. But I noticed some slight background noise coming from tweeters, I think it may come from the head unit, because both the red and the brown cable of the harness, whick provides the power supply for the OEM amp, are now open, I don't use them any more. I would try to connect this brown cable to my PDX ground just to rebuild a common ground, my question: would it cause problem?

BTW. the PDX is very good for Mid and Highs, but not good enough for Subs, the JL slash provides much more powerful deep sound contrarily.

[Technic]

Originally Posted by jonywalker

I replaced the OEM-amp completely with PDX-4.100 and JL Audio Slash 300/2, where the PDX is used to drive Mid and High channels, and the JL Slash the sub-channels. I know it is a little strange combination with class D and class AB, but because of the small size of PDX I did a super OEM-look installation, and the sound quility of this combination is excellent. But I noticed some slight background noise coming from tweeters, I think it may come from the head unit, because both the red and the brown cable of the harness, whick provides the power supply for the OEM amp, are now open, I don't use them any more. I would try to connect this brown cable to my PDX ground just to rebuild a common ground, my question: would it cause problem?

BTW. the PDX is very good for Mid and Highs, but not good enough for Subs, the JL slash provides much more powerful deep sound contrarily.

No, just make sure that that brown wire is in fact ground...

[jonywalker]

I measured these two points, they were already circuited to the common ground somewhere in the system so there is no need to wire them again, therefore the background noise is NO MORE ELIMINABLE, a little pity to the system which might already be present just I did not notice it before.
Could any one also confirm this perceptible background noise if music source is paused, of course the engine is off? I suspect the noise is originated from head unit because if I turn the volum control to minimum there is no noise output from amps.

[Technic]

Originally Posted by jonywalker

I measured these two points, they were already circuited to the common ground somewhere in the system so there is no need to wire them again, therefore the background noise is NO MORE ELIMINABLE, a little pity to the system which might already be present just I did not notice it before.
Could any one also confirm this perceptible background noise if music source is paused, of course the engine is off? I suspect the noise is originated from head unit because if I turn the volum control to minimum there is no noise output from amps.

I would still connect it, even as it is common ground. There's nothing that says that before going to ground is going thru some noise suppressor circuit somewhere in the car.

Remember, that was the ground that the OEM amp was using.

Another thing: check the gains of the PDX amp. They should be set at minimum, without any LOC. Also check how tight the RCA connection is made at the OEM HU speaker outputs.