JD NC

I have polk db6501's, which are the same speaker as your dxi's and also fit the oem baskets, but I ended up using the ring brackets that came with the polks instead.

I put the crossovers in the black box in the door. Mount them with Velcro stickies so they won't rattle, and run a little extra wire back behind the woofer to plug into the oem speaker adapter and you're all set.

CoolGuy094

Alright, everything is finally wired in, routed, and secured. Sounds great! Just need to mess with the gain setting on the amp a bit to maximize listening power, lol.

So it seems like people have had mixed success tapping into the antenna wire and using it as the turn on signal for the amp. Some people said it worked for all inputs, some said it only worked in AM/FM and not in CD mode. I, unfortunately, had the bad luck of not finding out this information until after I had tapped into the antenna wire, and the all turned off when I switched to CD mode. Is this a difference is model years? My antenna/remote turn on wire in the back of the head unit is yellow/green. Some people said theirs was blue/white... is that the case with aftermarket head units? Anyway, I decided to just tap the +12 white /red wire and use it as the turn on signal. The amp is on when the key is switched on now, and will not turn off when the radio is turned off, but whatever... I never turn the radio off anyway.

CoolGuy094

OK so all this talk about interference in the speaker wire has come full circle. I tried to do everything I could to route the speaker wires to avoid other wires in the car, but I still have a distinct whine coming through the speakers that gets higher pitched as the RPM's increase. You can't really hear it unless the volume is almost all the way down or is turned all the way down with the radio still on. I assume this is from interference between a power wire and a speaker wire somewhere? Any way I can rectify this?

CoolGuy094

After some research it sounds like this may be due to a bad ground. The only ground that I installed is the ground to my amp, which I currently have connected under a bolt that attaches the hood release handle to the chassis. The loop connector is in sandwiched between the chassis and the bracket, with the bolt holding it all together. I did not remove the bracket and grind off any coating that may exist on the chassis at this point. I realize now that I should have done this and gotten down to the bare metal. I guess I will get down there, remove the bracket, Dremel down to bare metal at that connection point, re-install, and see if the whine still exists.

Is it OK to run the ground wire from the amp all the way back to the negative terminal on the battery? Would this "guarantee" the best possible ground? If so, could I just run the ground wire to the amp along side the power wire from the battery?

JD NC

Yes, that sounds like a ground issue. A ground loop isolator between the HU and amp may also work, but it doesn't fix the underlying problem, it just filters out the noise from the ground loop.

I don't think you need to run all the way back to the battery to get a good ground - it's also possible that the amp is properly grounded and the HU is the component with the bad ground so in that case, running back to the battery wouldn't help.

Question for guys with more wiring experience than me - is it OK to tap into the black ground wire of the HU harness when the amp is connected to a different fuse? That would seem to be an easy way to ensure that both components have the same ground, but I don't know if that would cause other problems.

CoolGuy094

Well, I am using the OEM head unit... so I would assume that if there wasn't an issue with whine before while I was still using the same head unit and the same wiring/ground to the head unit, then that wouldn't be where my issue is now, correct?

CoolGuy094

Also - is there a negative to turning the gain knob on the amp almost all the way down? I went through the steps of setting the gain by turning the amp gain all the way down, turning the volume to ~75% on the head unit, then slowly turning the amp gain up until I heard distortion/clipping, then dialed the amp gain back 1/8 a turn and leaving it set there. The problem with this is that now I have very little fine-adjustment on volume level at the low end. With every click/turn of the volume knob on my head unit its like the following:

0 - no sound
1 - light/medium, good for when talking to passenger
2 - medium, good when cruising but getting more difficult to talk to passenger
3 - loud, good for rocking out but can't hear passenger
4 - FAWK MY EARDRUMS
anything higher - immediate death

So I really only have like 3 settings that I can reasonably listen to. Its like from turning up the gain, I lost a level of fine-adjustment to the volume settings. Honestly, with the amp gain knob turned all the way down, the speakers still sound great! So is it OK to just leave the amp gain knob turned down?

JD NC

Not necessarily. The ground loop only forms when there are two components with two different ground potentials. Either component can work even if the ground potential is a little off, and if there are no other ground connections to form a loop, you won't get the hum.

Before you go through the trouble of fishing the ground wire through the firewall, just run the wire out the window and hook it up to the battery that way and see if the hum goes away. That will at least eliminate a few possibilities.

JD NC

Definitely turn the gain down. The procedure you used is to get the amp as high as possible without distortion, but no problem with turning it down if it's too powerful at low volumes.

CoolGuy094

Thanks JD! I turned the gain down over lunch. Muuuch better control over the volume now. Was top down and couldn't hear the whine anymore. Going to work on that later tonight.