QuestionI just rewired my truck's sound system. Everything except for the rear mids/tweats are hooked up to a 900watt 5channel amp. Everything hooked up smoothly until we noticed the loud annoying feedback sound coming from the speakers when the volume was low. (It's the high ringing sound that increases in pitch when the car is excellerating.) We made sure the RCA chords weren't near the power chord due to that being the leading cause, but no luck. We even switched the RCA's thinking they might not be any good. The ground wire only works when connected to the truck's chasity.
Can you please offer your advice on what i might be doing wrong here? I really want that feedback to go away. Thank you.
AnswerI get so tired of this one :)
Turn DOWN you amps' input levels.
I would bet a silver dollar that is what is wrong.
You can and will chase ground loops for ages if this is not done 1st.
From experience, I can tell you that 95 out of 100 systems (competition or not) have the amps gains set too high.
People install it, crank it all up, then call me to ask why there is noise.
I could tell you 7-8 ways to find how or where noise is entering the system, but if the gains are too high, none of them will get RID of it.
The funny part is that once the levels are set correctly, turning them up ANY is NOT going to add one bit of additional wattage or output!!!! These levels are s'posed to be set with the deck all the way up. ahem.. So if the deck can deliver enugh RCA (at 100%) to make the amps output thier rated RMS power, that is the correct spot. It usually is much lower than you would think. You should be able to crank it to 90-100% on the volume at the deck with ZERO clipping or distortion. That should give you a good referance point.
anyhow,
If you then still have noise, or if you plan to leave the gains that high, all you can do is supress the noise with a line loop isolator (rca type). Noise will still be there, but quieter.
