R3VLimited Forums

Go Back   R3VLimited Forums > E30 Technical Forums > Car Audio & Electronics

Reply
 
Thread Tools Search this Thread
Old 04-28-2019, 03:48 PM   #1
bradnic
No R3VLimiter
 
bradnic's Avatar
 
Join Date: Jul 2012
Location: Chicago
Posts: 3,236
Understanding E30 speaker and amp wiring

Posted this to Luke's wiring thread, but think it warrants it's own post. Should probably sticky this too.

Radios like the CM5908 and KE83ZBM have 4 amp channels (and a CD changer connector). the earlier radios like the CM5905, CM5907 and KE81ZBM only have 2 amp channels. If you have the 4 channel setup with the BMW Sound System (tweeters on all four corners for coupes and sedans, amp in the trunk), then the output wires from the head unit share a common ground. This common ground is terminated on those 2 brown wires that get screwed on to the back of the radio heatsink.

You have probably seen pics with early model E30s showing an external fader knob. That fader was how a 2 channel radio drove 4 sets of speakers in the early model cars.

In common ground 4 channel cars, the headhunt wiring included a 2 to 4 channel adapter harness that replaced the fader. One end of this adapter plugs into the fader socket in the wiring harness. The other end is a rectangular connector with 4 blades labeled LH (links hinted = left rear) and RH (rechts hinten = right rear). Those are the rear head unit output connections that get sent to the amp in the trunk.

Here is a standalone picture of the 2 to 4 channel adapter, part number 61101388934


Note that there are no ground wires in that harness - on either end. You can tell what the head unit output wires do from the color coding:
blue head unit wires are for the right channels
yellow head unit wires are for the left channels
blue or yellow red striped wires are for the front channels
blue or yellow black striped wires are for the right channels

Now regarding the BMW Sound System wiring, those head unit outputs get routed to your blaupunkt trunk amp harness - NOT TO THE SPEAKERS. It's about 90% certain that a 30 year old unserviced power amp is fried. You can either (1) rebuild it, (2) bypass it and run headunit only or (3) bypass it and replace with an aftermarket 4 or 5 channel amp. @Rontgen's post on Luke's amp bypass thread beautifully captures the bypass you need to do for case 2.


For case 3 you route the yellow and blue wire pairs to the aftermarket amp's speaker level inputs, and the aftermarket amp's outputs get wired to the black and grey striped wires that go to the four speaker sets.

Here are the power amp output wiring colors (probably posted for the 135th time lol)
grey amp wires are for the front speakers
black amp wires are for the rear speakers
grey or black wires with red stripes are left channel
grey or black wires with violet / purple stripes are left channel ground
grey or black wires with white stripes are right channel
grey or black wires with brown stripes are right channel ground


the three remaining power amp wires are self explanatory, red for battery, white for amp on/off and brown for ground.

FYI I'm working on an adapter harness for all this so no wire cutting is needed, but will be a while. First install will be Cosmo, my 86 Cosmoblau 325. It will be running an Infinity REF 4555A 5 channel amp and a JBL 1224SS trunk sub.

for completeness, here's a 1986 BMW Sound System schematic for TWO CHANNEL RADIOS showing the wiring for the radio, amp, speakers and power antenna. Note the radio output wiring is common ground.


Here's the same set of schematics for a 1989 late production BMW sound system car with FOUR CHANNEL RADIO wiring. Again the radio output wiring to the power amp is a common ground setup.

Finally, here's an 1989 4 CHANNEL RADIO ONLY late production schematic. Note each speaker has it's own ground wire. Early production is electrically the same with some harness connector differences


NOTE The 1989 325i / 325is electrical troubleshooting manual has 4 different radio + amp schematics based on early vs late production, radio only vs BMW Sound system. Make sure you're looking at the right version for your car!
-- 2 channel (up to early 88 or so) or 4 channel radio
-- radio only, or BMW Sound System with amp
-- coupe/sedan or convertible. Convertibles with BMW Sound System do not have rear tweeters, or crossovers on the rear speakers.
__________________
I BUY/SELL REFURBISHED CM5907s & CM5908s

HOWTOs:
DB vert plastic bumpers
OEM Keys
MTech1 docs

88 ix Lach/Card
91 ic Calypso 3.1
86 Cosmo 2.7

OEM+ or bust!


reelizmpro: I will always be an e30 guy.. I still do all of my own labor
TrentW: There's just something so right about a well-built M20 in an E30
e30m3s54turbo: I save my money for tuner parts.
bradnic is offline   Reply With Quote
Old 04-28-2019, 04:40 PM   #2
Zambuzan
Wrencher
 
Zambuzan's Avatar
 
Join Date: Nov 2017
Location: "Mostly Rust-Free" Florida
Posts: 235
Any suggestions for a newer amp to install in the stock trunk location? Or is it not worth the trouble?
__________________
"Time doesn't heal anything... It just teaches us how to live with the pain." - My Cracked Dashboard
Zambuzan is offline   Reply With Quote
Old 04-28-2019, 05:12 PM   #3
bradnic
No R3VLimiter
 
bradnic's Avatar
 
Join Date: Jul 2012
Location: Chicago
Posts: 3,236
Quote:
Originally Posted by Zambuzan View Post
Any suggestions for a newer amp to install in the stock trunk location? Or is it not worth the trouble?
I’m actually working on an amp bypass kit that uses the existing amp housing. You’ll be able to use a 5 channel amp and a trunk sub with it. Aiming the first install on my 86 325, using an Infinity Reference 4555a and a JBL 1224Ss 12” trunk sub. Just finished a BMW Sound System rear parcel shelf retrofit on that car actually. Front tweeters are installed too, and have the OEM front speakers on order from Germany.
bradnic is offline   Reply With Quote
Old 04-28-2019, 06:13 PM   #4
Zambuzan
Wrencher
 
Zambuzan's Avatar
 
Join Date: Nov 2017
Location: "Mostly Rust-Free" Florida
Posts: 235
Quote:
Originally Posted by bradnic View Post
Iím actually working on an amp bypass kit that uses the existing amp housing. Youíll be able to use a 5 channel amp and a trunk sub with it. Aiming the first install on my 86 325, using an Infinity Reference 4555a and a JBL 1224Ss 12Ē trunk sub. Just finished a BMW Sound System rear parcel shelf retrofit on that car actually. Front tweeters are installed too, and have the OEM front speakers on order from Germany.
Wait wut? You mean to physically place that Infinity amp in the OEM trunk location? Am I misunderstanding? Or do you mean modifying the internals of the OEM amp?
I should've added in my original post that my goal would be to have an amp hidden, aka not taking up trunk space, just like the factory amp.
__________________
"Time doesn't heal anything... It just teaches us how to live with the pain." - My Cracked Dashboard
Zambuzan is offline   Reply With Quote
Old 04-29-2019, 04:37 AM   #5
bradnic
No R3VLimiter
 
bradnic's Avatar
 
Join Date: Jul 2012
Location: Chicago
Posts: 3,236
Yes basically an integrated amp+trunk sub connected through the OEM trunk amp housing. No cut wires. If you’re going to install a trunk sub anyway, this is probably the best option

If you’re lucky enough to have original BMW Sound System wiring it will be plug-n-play to upgrade power and add a trunk sub... well for coupes and sedans with trunk battery locations anyway.
__________________
I BUY/SELL REFURBISHED CM5907s & CM5908s

HOWTOs:
DB vert plastic bumpers
OEM Keys
MTech1 docs

88 ix Lach/Card
91 ic Calypso 3.1
86 Cosmo 2.7

OEM+ or bust!


reelizmpro: I will always be an e30 guy.. I still do all of my own labor
TrentW: There's just something so right about a well-built M20 in an E30
e30m3s54turbo: I save my money for tuner parts.

Last edited by bradnic; 04-29-2019 at 06:17 AM.
bradnic is offline   Reply With Quote
Old 04-29-2019, 06:03 AM   #6
bradnic
No R3VLimiter
 
bradnic's Avatar
 
Join Date: Jul 2012
Location: Chicago
Posts: 3,236
Quote:
Originally Posted by Zambuzan View Post
I should've added in my original post that my goal would be to have an amp hidden, aka not taking up trunk space, just like the factory amp.
Answering your question directly, a class D 4 channel amp could potentially fit in the original amp housing. Itís a lot of work though. You can accomplish the same thing with an amp bypass and wiring in a small commercial class d amp. It does require cutting the harness though. The key issue is sourcing the connector on the amp housing. I havenít been able to find it yet.
bradnic is offline   Reply With Quote
Old 06-12-2019, 01:06 PM   #7
NeverEnough02
Wrencher
 
Join Date: Mar 2015
Location: Boston, MA
Posts: 218
Quote:
Originally Posted by bradnic View Post
Answering your question directly, a class D 4 channel amp could potentially fit in the original amp housing. Itís a lot of work though. You can accomplish the same thing with an amp bypass and wiring in a small commercial class d amp. It does require cutting the harness though. The key issue is sourcing the connector on the amp housing. I havenít been able to find it yet.
Any luck with this? I am thinking I can use the radio output lines to feed signal to a digital sound processor. It would be great to just plug in a harness instead of the factory amp so, the factory harness is saved. I am not sure what kid of wattage is coming out of the OEM head unit. Would I wire the signal to speaker level inputs or adapt them to an RCA input?
NeverEnough02 is offline   Reply With Quote
Old 06-16-2019, 08:59 AM   #8
AndrewBird
The Mad Scientist
 
AndrewBird's Avatar
 
Join Date: Oct 2003
Location: Portland, OR
Posts: 11,718
If you can't find the stock amp connector anywhere, you might consider replicating it in CAD and 3D printing it.

There are lots of places to get high quality 3D prints now a days. Stratasys, Xometry, ProtoLabs to name a few.
__________________
AndrewBird is offline   Reply With Quote
Old 06-16-2019, 09:40 AM   #9
dlmrun2002
Mod Crazy
 
dlmrun2002's Avatar
 
Join Date: Apr 2007
Location: New York
Posts: 764
Send a message via Yahoo to dlmrun2002
Lets face it. BMW makes sh*tty stereo's. The speakers wires are ok. Get a new head unit, a quality amp and some good speakers with some sub setup. Install. I use to stick a HUGE PPI 4800.2 on trunk wall between tail lights.Right next to the battery and took up very little trunk space flat against the rear valance panel.
dlmrun2002 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 04:05 AM.


Powered by vBulletin® Version 3.8.10
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright 2004 - 2020 R3VLimited LLC