Help wiring multi-amp system in my BMW 528i.


Shaun543

CarAudio.com Newbie
Nov 14, 2019
3
0
Ohio
Hello, new member I am trying to get my system wired in my BMW I have 2 8” under-seat subs, 4 channels all around, and a JL 10w3 in trunk I have a PnP harness to bypass factory amp and provide connection to outside amps having problems deciding how to wire the 3 amps (mainly signal wiring). My 4ch does not have pass-thru signal out-puts
18970
 

homosexualthug69

CarAudio.com Newbie
Nov 4, 2019
9
0
Ft. Worth, TX
Are you replacing the underseat subs with the Earthquakes(or anything else?) If you are just adding an amp to the stock speakers, I wouldn't even bother. Mine distort on the factory Hifi amp on certain songs.('19 440i GC). I would just eliminate them or leave them running off the factory amp, thus eliminating your problem.

Now if you are replacing them and have to run an amp, you can either put Y-splitters on the sub rca's or you will have to swap equipment, amp or processor, to allow for 6.1 channels. This is ideal and my ultimate goal for my car, having the Earthquakes under seat running the midbass freq's.
 

THATpurpleKUSH

Smoke weed everyday
10+ year member
Sep 30, 2009
7,494
540
Banging gears and passing queeers
Aftermarket audio in a modern BMW is an absolute nightmare and just asking for trouble. The cars are so electronic laden and the electronics themselves are so so sensitive that the slightest voltage drop sends everything into a frenzy. The techs at work have to hook the cars up to a battery charger for simple software flashing because of the sensitivity to voltage drop. You have been warned.
 
OP
S

Shaun543

CarAudio.com Newbie
Nov 14, 2019
3
0
Ohio
Are you replacing the underseat subs with the Earthquakes(or anything else?) If you are just adding an amp to the stock speakers, I wouldn't even bother. Mine distort on the factory Hifi amp on certain songs.('19 440i GC). I would just eliminate them or leave them running off the factory amp, thus eliminating your problem.

Now if you are replacing them and have to run an amp, you can either put Y-splitters on the sub rca's or you will have to swap equipment, amp or processor, to allow for 6.1 channels. This is ideal and my ultimate goal for my car, having the Earthquakes under seat running the midbass freq's.
I replaced factory with Rockford Fosgate Components made for BMW and Earthquake underseat subs. I built this make up in my diagram and realized that it was overkill. Not in power, but in presence. I scrapped all that and wound up doing a 5-channel Alpine amp to run the 4 mains and bridge the two underseat subs (series 2ohm to create 4ohm load). From that I went to a JL JX500/1D to power my 10" W3 trunk sub.

The only "BMW" issue I had is with the module for the rear view camera. It stopped working and I did tons of research on it and could not come up with anything. It was screwed to the metal cage that the factory amp was on that I removed, but the module itself was in a metal housing. I had it against metal, but it just would not work. I tried, for shits and giggles, running a ground off that metal module to a good place in the area where the amp was removed and viola, it works again.

With this set-up, I buried the 5-channel in the area the previous amp was in, and nestled the mono amp in a recess in the trunk. Its a very clean install now and not overwhelming.

My only issue now is a bit of white noise coming through the speakers. It is not dependent on head unit volume level, just a constant low volume "hiss" that you do not notice when playing music, but do when there is a lull between songs. Any idea on how to fix this?
 

homosexualthug69

CarAudio.com Newbie
Nov 4, 2019
9
0
Ft. Worth, TX
My only issue now is a bit of white noise coming through the speakers. It is not dependent on head unit volume level, just a constant low volume "hiss" that you do not notice when playing music, but do when there is a lull between songs. Any idea on how to fix this?

Nice. The hiss is due to the removal of the the stock amp. The only options are an amp with balanced inputs like the JL XD600/6 or the Bimmertech(or BavSound) replacement amps. Or you can re-install your factory amp and then grab the high level signals after the amp into an Audiocontrol LC6i or other processor.

I'll be scouring the BMW boards after Christmas for a Bimmertech or Bav, due to the RCA out for wiring simplicity, and replacing all of the factory speakers. I installed my sub this past weekend and it drowns out the mids/highs on the factory amp.
 
Last edited:
OP
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Shaun543

CarAudio.com Newbie
Nov 14, 2019
3
0
Ohio
Nice. The hiss is due to the removal of the the stock amp. The only options are an amp with balanced inputs like the JL XD600/6 or the Bimmertech(or BavSound) replacement amps. Or you can re-install your factory amp and then grab the high level signals after the amp into an Audiocontrol LC6i or other processor.

I'll be scouring the BMW boards after Christmas for a Bimmertech or Bav, due to the RCA out for wiring simplicity, and replacing all of the factory speakers. I installed my sub this past weekend and it drowns out the mids/highs on the factory amp.
So I went the round of the LC8i and reinstalled the factory amp and ran the after factory amp speaker wires to it, RCA's to the 5 channel and the mono amps. Then back from the 5-channel to the speaker wires. Everything flows fine and is clean, the issue is that now I think my low bass is non-existent. I have (2) JL 10x3v3 in a sealed box running 2-ohm to a double chamber sealed box powered by a JX500/1d amp. The power is more than enough, but my bass is seriously lacking. On rap type songs, it is pretty good, but on rock it almost does not exist.

Looking at the LC8i, I have fronts into channel one, rears into channel 2, subs into channel 3, channel 4 is empty. Then outs I have mirrored channel 1-3 in's and have the JL amp running from channel 4 outputs (pulls signal automatically from channel 3 input).

I think I may be fighting the LPF that is in the factory amp and not getting the appropriate signal to power the JLs correctly.

Thoughts of a fix?

Thanks,
Shaun
 

homosexualthug69

CarAudio.com Newbie
Nov 4, 2019
9
0
Ft. Worth, TX
So I went the round of the LC8i and reinstalled the factory amp and ran the after factory amp speaker wires to it, RCA's to the 5 channel and the mono amps. Then back from the 5-channel to the speaker wires. Everything flows fine and is clean, the issue is that now I think my low bass is non-existent. I have (2) JL 10x3v3 in a sealed box running 2-ohm to a double chamber sealed box powered by a JX500/1d amp. The power is more than enough, but my bass is seriously lacking. On rap type songs, it is pretty good, but on rock it almost does not exist.

Looking at the LC8i, I have fronts into channel one, rears into channel 2, subs into channel 3, channel 4 is empty. Then outs I have mirrored channel 1-3 in's and have the JL amp running from channel 4 outputs (pulls signal automatically from channel 3 input).

I think I may be fighting the LPF that is in the factory amp and not getting the appropriate signal to power the JLs correctly.

Thoughts of a fix?

Thanks,
Shaun
That's a head scratcher man. The harness I have, Technic PNP , simply splits off the sub signal and sends it to a cheapy LOC and it absolutely pounds. It's a Sundown SA-12 on 1k watts. Have you tried the full range signal going to the rears? It might be worth jumping the signal in to CH 2 to CH 3( just connect some speaker wire from Ch 2 to 3)

You might register and ask in the audio section on Bimmerpost, there are some there that are more knowledgeable than I with full aftermarket replacements. Here is a thread that goes into it. Linky
 

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