Originally Posted by dmatre
I've noticed that my system also has a VERY SLIGHT amount of tweeter hiss when the car is powered on.
BUT ... with the car running, there's enough ambient noise that the hiss is undetectable, so I don't feel that it's a problem at all (for me). I can't hear the hiss if idling in the garage, so you can bet that on the road it's a non-issue as well.
On my system, the hiss is definitely proportional to the gain, but I've got the gains rather low, so that resolves that issue. (The system will still get uncomfortably loud with the gains set low)
Is your hiss bad enough to hear it if the car's running? Or are you checking it with the car powered up but not running?
I have the same problem as you. Not noticeable when the engine is running and proportional to the amp gain. Increasing the volume of the head unit doesn't increase to volume of the noise except when the HU volume is very near its max.
If the volume of the HU is zero there will be no noise at all but it's enough to increase the volume one click for the noise to appear.
No noise if a smart phone is connected directly to the amp.
I have the relay from technics harness very close to my rca-cables. Could the relay cause any interference?