mossman77

It happens irregardless of the source, and it doesn't happen every time, which makes it even more difficult to track down. I'll experiment with different settings on my DQDX processor and see what happens.

aleo12

Mine does the exactly same thing, as soon as the car turns off a very loud audible hum happens.

I couldn't figure it out, my only solution was to put in a switch for the remote turn on and just turn off and on the system manually everytime I wanted to use it

mossman77

Mine doesn't hum at all. The bass just gets significantly louder when I cut off the engine. It doesn't happen every time, which is making it difficult to track down.

csmeance

this is going to sound crazy, but try running the system from another power source such as another car battery and run the car from the battery that's intalled. See if it gets louder with the TL on/off. If it does, I'm thinking it could be the remote wire or a shared ground causing trouble.

mossman77

Would that even work? The head unit would be powered off the car battery and the amp would be powered off the spare. I think the better approach would be to monitor some voltages and see what is changing. I wouldn't expect the remote signal voltage to have any affect on the volume. The amp is either on or it isn't. And the amp has voltage regulation circuitry, so I don't think the battery voltage is the either. I'm going to start with monitoring the line level voltages going into and out of the pre-amp.

thoiboi

Well that's the point.. trying to rule out what the culprit is..

csmeance

By trying another power source for the Amp you can see if the issue lies with the signal from the HU or from the battery in the car! You can buy an oscilloscope and read the wave forms of the speakers and see what is going on too with the car running and off.

Yes there is circuity inside the AMP, however it could be malfunctioning and causing a power drop when the car is at 14V (on) for whatever reason. OR, you have a bad ground and the system can't discharge the energy from the grounds thus not allowing enough power to flow and reducing volume.

Panasonic made the remote wire 9V for some reason on the 3G TL and it's caused headaches, so you might be having an issue if the amp need 12V.

mossman77

I have an oscilloscope. Just haven't had time to look into this.

The ground thing doesn't make sense because this is an intermittent issue.

This is a 4th gen TL, and like I said, the amp is either on or off given a range of remote voltages. A varying remote voltage would not cause the amplifier output to vary.