Head unit distorting when using subwoofers, deck losing power?

[ancorp 10+ year member]

Been running my Mazda3 with its stock stereo and speakers, along with a line converter wired into an amp and subwoofer for a while now. No issues, using various amplifiers and various speakers and subs wired to those amplifiers.

Today I replaced the stock stereo with a Pioneer deck. It sounds great with the stock speakers. Once I turn on, and turn up my subwoofer amp, it starts to clip the deck. It's as if the deck is not getting enough power to its built in amplifier. Turning down or off the sub amp cleans up the decks output instantly. I can crank the volume quite high before the stock speakers start to distort, but as soon as the sub starts to pound, the deck goes into clipping.

Perhaps I have to wire my deck directly to the battery? Or would a cheap ground cable to the amp cause things like this?

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[assassin1840 10+ year member]

i was selling a system to my co worker and just the week before i had it hooked up to my car full blast with no problems and when i was testing it out on his car he had this cheap 6 gauge wire and it did the same thing it was the cheap wire. but what is your sub set up

 

[ancorp 10+ year member]

I'm running a Kaption D1000.1 for a while now. It does 1000w RMS at 1ohm, 730 and 2, and 400 at 4. Currently pushing just one JL 10W0V2, 4 ohm. So the amp isn't drawing much current since its only pumping 400 watts. Even running four 10s on that amp (parallel, 1 ohm total, 1000w RMS) my stock deck had no issue what so ever. Only with this pioneer deck.

It's very noticeable difference when the volume is up high. I can comfortably raise it to a good 60-70% of maximum volume with the subwoofer off, then as I turn it on and crank the sub, the speakers start to clip really really bad.

 

[ancorp 10+ year member]

Replacing the RCA cable with a higher end one solved this issue completely. Another issue arises though - wiring the amp down to 2 ohms causes nasty ground feedback noise. Unplugging the RCAs stops the noise. Tried different ground cables. Runs ok on 4 ohms.

 

[assassin1840 10+ year member]

what kind of wire are u using i believe if your wires are not well isolated it can cause noise if your rca cables are with your power cables

 

[keep_hope_alive Premium Member]

If you had RCA issues, then you probably damaged the Pioneer outputs, a common problem. Ground one of the RCA shields and your noise should go away.

 

[keep_hope_alive Premium Member]

Also, I assume you are no longer using the LOC and have your new RCA's directly from the head unit?

 

[ancorp 10+ year member]

My RCAs run on the opposite side of the power wiring. My remote wire is running along side them though.

Yes I took out the LOC and carefully taped up the spliced wiring. Using the sub outputs. So I could just take a short wire from my amps ground connection to one of the RCA negatives? Or do I have to do it on the deck end? Can I ground to the ground connector in the decks wiring, or do I have to ground directly to bare metal somewhere in the car?

 

[keep_hope_alive Premium Member]

From head unit ground to RCA shield, you'll have to tape a wire on it. This is a well documented issue for some specific head units.

Where/how is the amp grounded?

 

[ancorp 10+ year member]

Will try that tomorrow morning, thanks!

The amp is grounded to the inside of the car trunk. Paint sanded off before drilling of course.

 

[ancorp 10+ year member]

Grounding the RCAs solved the loud noise at 2 ohms for my amp, thank you very much sir!

After grounding the RCAs I was left with my usual slight background buzzes and noises from the car (even when just running on battery) that I had when running the stock deck also. I replaced my battery ground to car cable with a 2 gauge, and ran a gigantic 0/2 gauge ground cable for my amp in the trunk. Also removed the Remote Gain knob that was running along side my power cable. Now the subs are fully noise free.