Thread: Amp Volume Fluctuations

Yup, I doubled up on the ground wire too. The gain was set pretty high, but I turned it down and it still did it.

If you have a second car available you could run the power wire to that car and isolate it to either your car or your amp. I will say that just because your battery and alternator are good in terms of the car they may not be up to the task of covering your audio system and your car. Do you have a volt meter? If so you could have a friend help and see what the voltage is at the amp when you encounter the problem (do this one first).

this only happens when I'm driving the car. When I'm parked I can step on the gas and brake all I want and nothing happens. Maybe I'll run some wires from the battery to my voltmeter and watch the voltage as I drive around.

Run them from the amp, that will give you a better idea.

When I'm parked I can step on the gas and brake all I want and nothing happens.

Okay now this is just weird. I'll have to sleep on this one, the only difference is the load on the engine? I'm lost let us know what the voltage is doing at the amp.

P.S. Is there anyway you can switch amps? It should not do anything but I have seen stranger.

Got to go back to the basics.

1. The power is connect straight to the battery not anywhere elase.
2. The ground has to go to a hard ground connection like under a seat belt bolt, no where else.
3. The ground from the battery to the ground where the Amp is grounded needs to be checked. Your ground at the amp may be tight but the grounding strap from the ALT / Battery to the frame may be bad. Resistance measurements between the ground at the amp and the negative on the battery must be less than 1 ohm.

As for only happening during driving I suspect that there is a grounding issue. On some vehicles the ground is run from the battery to the engine block and from there to the rest of the chassis. Not even necessarily through a dedicated strap. The ground through out the vehicle chassis some times is only connected via, linkages or fastening bolts that can become corroded or loose over time. As you get on the gas the engine tilts the mounts flex and the ground can become internmittant. Smae goes for braking. It does not happen as much while parked because the frame and engine mounts are not loaded so the flex is less.

The way to troubleshoot this is to temporatily run the ground directly from the battery to the amp like the power wire and see if the problem goes away.

If it does then the entire ground path between the ground point on the amp and the negative terminal on the battery must be checked.

Also you need to measure the voltage AT the amp while driving, not at the battery to get any useful results.

^^ much smarter than me I would have never come up with that possibility.

I'm pretty confident I have it grounded pretty well (it is to a seat-belt bolt) and I've tried moving it to a couple of other locations to no avail. I never would have thought of flexing on the frame... that's worth a look by running a ground to the battery.

Thanks for the idea, I'll let you know how it works out

I checked the resistance from the amp ground to the negative terminal on the battery, and it was 10 Ohms! ....so I took my dremel and cleaned up the point where the grounding strap went on the chassis and now it's .4 Ohms, but it still has the problem. I haven't run a dedicated cable for the ground yet (I have to go buy one).

As I drive around the voltage dips from about 13.8 to 13.1 when I step on the gas or brake, and that's when the volume dips.