A4ia

I finished one door this weekend for my Focal 130k's, ran separate woofer and tweeter cable back to the rear seat where I mounted the crossover. Modified the stock Audi harness to accept the Blaupunkt pins, ran that back to the trunk... then decided I had enough stuff to do a dry run. I hooked up my new Precision Power PCX-440 to the power leads, plugged in the RCA's, turn-on lead, and speaker wire for the one door (all other speakers disconnected). The good news is that the amp turns on and off correctly, the door drivers work, and there's no rattling.

Here's the bad news:
1) If you rest your elbow on the door you notice how much more the door is shaking due to a nice kevlar Focal driver in it... it doesn't rattle, but I'm not sure this is normal... is the driver supposed to be mechanically isolated from the door somehow? Mine is screwed down hard onto my custom mounting plate which is screwed down hard onto the original hole.

2) It sounded good, but not as clear as I had hoped... I think I'll hold off judgement until I finish the other front door and add in the rear deck.

3) When the head-unit is turned on (and therefore the amp is on), there is a noticable hiss that comes from the tweeter. At first I thought it was noise coming from the head-unit, but if you unplug the RCAs from the amp, there is no change... so obviously the amp is making this noise on it's own. My ground is connected to a seat-belt bolt and the power runs down the side, and through the triangular grommet right next to the battery. Both are 4 gauge. Is this a noisy amp? Is this a grounding issue? Or is the power cable picking up something from the ECU... and is the ECU even running with the engine off?

What do you guys think?

D.Ross

does this hiss come out both sides or just one? (maybe the side you ran the power down?)

A4ia

... and it was the passenger door... the power and ground run down the other side. So it's a good guess, but that can't be it. I'm thinking I'll move the ground first, and maybe consider a big filter capacitor for the power cable.

John P. (TT 225)

Is your amp's gain turned up too high?

A4ia

and the noise didn't seem to get any louder with the gain trimmed up a little bit.

I'm starting to think it's almost definitely a power supply noise problem (noisy power or ground)

ARK

notice it.

A4ia

but I have sensitive ears, and in my opinion, an amp with it's gains turned all the way down should be silent. If they can make home amps that are silent, a car should be no different.

Oh well... thanks again!