Is the amp at fault?

**Tim Lake** · 06-24-2006, 03:18 PM

I have had no end of trouble with alternator whine feedback on my audio.
I have checked the grounding and redone them all at least twice. I have ground loop isolators on everything and those little magnetic clip jobbies that go round the wires.
I have NEVER been able to shift the feedback completely. Now I have fitted my new computer touchscreen and everything it's back with a vengeance!

I have a lot of earthed stuff (two amps, active crossover, computer startup controller, screen) and they are all solid earths!

If I remove the fuse from the 2-way amp (which goes to the components) then it stops. Is it possible/likely that the amp is at fault and is there a way to find out without replacing the amp?

**Tim Lake** · 06-25-2006, 07:27 AM

bump

**Will Albers** · 06-25-2006, 09:15 AM

Did you isolate and follow the steps i posted in the stickies at the top? You need to start pulling out components.

**Shadow** · 06-25-2006, 11:47 AM

Did you by any chance upgrade your battery and engine grounds?

**Tim Lake** · 06-25-2006, 02:59 PM

@Will : I have disconnected things in turn and it does seem to be the amp. If I pull the fuse from that amp then run the car there is no feedback at all.

@Shadow: No I didn't do either of those.

**Will Albers** · 06-25-2006, 03:58 PM

if you pull the fuse from the amp, there is no sound at all, therefore no feedback.

If you plug a pair of headphones into the compuetr sound card, do you hear the noise?

What happens if you go directly from the carouter to the amp?

**Shadow** · 06-25-2006, 05:16 PM

In a PC case the power supply and motherboard share a common ground. If you're using a non-standard PC case then you should check into this.

**Tim Lake** · 06-25-2006, 05:20 PM

I have two amps and the other one is still on but doesn't cause the feedback.

I already go direct from the carputer to the amp (thanks to your prior advice).

I haven't tried the headphone thing yet but I will do and let you know.

**Will Albers** · 06-25-2006, 07:34 PM

ahhh, ok, so one causes feedback and the other does not? VERY interesting. Are both amps grounded to the same spot? Have you tried using a test speaker? same thing?

**Tim Lake** · 06-26-2006, 04:40 AM

They aren't grounded to the same spot cos the mono amps grounding spot is now VERY difficult to get to. The component amp does have a good solid ground.
How do you mean, use a test speaker?