Stock Sub working w/ aftermarket hu - Page 4

2turbo1sup · 06-14-09, 03:37 AM

Yep, I tried everything from doing the wiring in the diagrams I posted earlier, to running wires directly to the sub; basically every combination imaginable. I give up.

Time for a new sub

RANDY P · 06-15-09, 04:36 PM

Dropped the glovebox, backseat, removed the changer, unplugged the outputs on the factory Pioneer amp, spliced into the speaker outputs and byassed the amp.

A little over 50FT of speaker wire later, everything works as it should. Deck power sounds identical to the factory pioneer amp, literally sounds the same.

I was in a rush to get to a bday party so I left the factory amp plugged in and powered up - literally the only wires cut were the output wires to the speakers. I didn't have time to experiment to see what happens if I remove the stock amp all together. It seems that the remote on (for the sub amp and power ant controls) are all daisychained through the amp.

Behind the dash, I have the Metra wiring harness adaptor wired up as it should be except no RCA input, 4 sets of speakers going to the back of the car supplying signal to the factory speaker wiring, and a "Phono Jack" spliced into the subwoofer input leads on the car and plugged into the sub out on my HU.

Like I said, works like a champ. Literally the only thing missing is the changer I left out.

In a few months when budget permits 4x 6.5" seperates, and a freeair 10" in factory location with one hell of a multichannel amp running it all will finish this deal up.

shern · 06-17-09, 04:39 PM

Randy P

I just helped a buddy install an Alpine HU into his SC with the Metra harness. I have EXACTLY the same issue you describe. As soon as you power up the radio, there is a buzz, even when the car is not running. And then alternator whine. Pull the RCAs and it's gone.

I suspect some sort of ground loop between the HU and the factory amp. I noticed that the signal grounds and the chassis ground are connected. I'm a bit stumped. If somebody has some insight, please chime in.

2turbo1sup · 06-17-09, 06:40 PM

RANDYP; I should try that method and put the sub and speaker amp back into the car. I'll try it after I get off work and post my results. Question: did you splice in power to the sub amp harness on the back of the HU?

RANDY P · 06-18-09, 01:48 AM

Quote:

Originally Posted by shern

Randy P

I just helped a buddy install an Alpine HU into his SC with the Metra harness. I have EXACTLY the same issue you describe. As soon as you power up the radio, there is a buzz, even when the car is not running. And then alternator whine. Pull the RCAs and it's gone.

I suspect some sort of ground loop between the HU and the factory amp. I noticed that the signal grounds and the chassis ground are connected. I'm a bit stumped. If somebody has some insight, please chime in.

The noise is because the ground reference points are so far off due to impedance differences between the inputs / outputs. Metra did a crappy job on this harness. We could probably just simply hook up the speaker + on ecah corner to the harness and it'll probably give us less problems, but I don't feel like risking damaging my deck to see if it works.

Used to work on other cars (like OEM BMW) that way.

It's not worth screwing with, bypass the amp. It's $11 in speaker wire and the quickest answer. You'll spend all day fooling with changing grounds, etc etc total waste of a day, plus you aren't risking burning up your HU outputs. The harness in the trunk is even long enough you can stand outside and cut it. Pretty sweet.

Quote:

Originally Posted by 2turbo1sup

RANDYP; I should try that method and put the sub and speaker amp back into the car. I'll try it after I get off work and post my results. Question: did you splice in power to the sub amp harness on the back of the HU?

Nope, behind the dash the only harness off the original radio that is being used is the one the Metra plugs into. The other harnesses, including the dedicated sub harness are just sitting there.

I'm sure someone out there will insist removing the factory amp and running all this wire is the answer but this is the fastest, neatest and is the least amount of butchery to get it to work. I can return my car to full stock in under 30 minutes if I need to.

rjp

wonton · 06-20-09, 09:31 AM

will this work 4 the 2gsmodel as well???

joliroger4 · 07-06-09, 03:45 PM

Has anyone tried jumping the amp out totally at the amp? Instead of running all that wire, just jump the inputs and outputs together. Also has anyone tried any of the plugnplay harnesses with ground loop isolators with success? Just getting ready to swap a kenwood in my SC and trying to get as prepared as possible. Thanks.