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Understanding E30 speaker and amp wiring

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    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 a couple of plug and play adapter harnesses 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.
    Last edited by bradnic; 06-30-2019, 11:32 AM.
    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.

    #2
    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

    Comment


      #3
      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.
      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.

      Comment


        #4
        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

        Comment


          #5
          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.

          EDIT: I will have two different harness types.. if you're just adding a powered trunk sub it will simply tap into the premium amp wiring directly. Super easy.
          Last edited by bradnic; 06-30-2019, 11:29 AM.
          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.

          Comment


            #6
            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.
            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.

            Comment


              #7
              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?

              Comment


                #8
                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.
                sigpic

                Comment


                  #9
                  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.

                  Comment


                    #10
                    @dimrun2002 I respect your view, but generally disagree.
                    - The E30 headunits were made by Alpine and Pioneer, not BMW.
                    - The BMW Sound System speaker drivers are very high quality actually.

                    DIY Areas for improvement from the original setup:
                    - If you have the radio only standard setup then definitely replace all the speaker drivers with better stuff
                    - If you have a convertible replace the rear speakers with coaxial drivers

                    Advanced upgrades from the original setup:
                    - Retrofit the BMW Sound System. this is a significant undertaking though that includes replacing the main rear speaker harness, all of the speaker drivers, adding tweeter wiring and door tweeter pods. It's definitely worth it if you don't have it, but sourcing all the bits is difficult.

                    - Add a powered sub to a BMW Sound System setup. Requires some custom harness work.

                    - Replace the premium amp with an external 5 channel amp and a passive sub.
                    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.

                    Comment


                      #11
                      Originally posted by NeverEnough02 View Post
                      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?
                      There are line level converters out there if you want to use external amps and line level inputs..

                      I did get an Infinity Basslink DC powered sub (10" driver+ 10" passive radiator) setup working with the existing premium amp. but it's too big for my vert :-)
                      Sounds darn good though.

                      Still looking for the connector. I will have two plug-n-play two harness adapter kits when I'm finished:

                      -- one to keep the OEM blaupunkt premium amp and add a powered sub.
                      -- one to replace the OEM premium amp with an external 5 channel amp and sub.

                      Originally posted by dlmrun2002 View Post
                      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.
                      That's a cool mount location but you do need to extend wiring back around further. Most folks probably mount behind their rear seat.

                      Looks like the PPI 4800.2 is a 4 channel amp. Infinity sells a Reference 4555 5 channel that's smaller, $100 less and supports 500W to the sub. you don't really need big power for the other channels - 45W should be enough for most folks.

                      Click on pic for Crutchfield listing


                      Stay tuned..
                      Last edited by bradnic; 06-30-2019, 11:27 AM.
                      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.

                      Comment


                        #12
                        Originally posted by bradnic View Post
                        Iím actually working on an amp bypass kit that uses the existing amp housing.
                        Awesome! Let's see some work!


                        Originally posted by bradnic View Post
                        @dimrun2002 I respect your view, but generally disagree.
                        - The E30 headunits were made by Alpine and Pioneer, not BMW.
                        - The BMW Sound System speaker drivers are very high quality actually.
                        Yhe stock BMW speakers are crap. They are fantastic if you consider 1990's factory car speakers as a baseline. But even driven with a nice amp, they are muddy, with a ton of resonance that make it sound like there is a midget ringing a bell, all the while banging on a Amazon cardboard box in your e30.

                        Luke Fisher tried to get us all to go down that rabbit hole.
                        Originally posted by Matt-B
                        hey does anyone know anyone who gets upset and makes electronics?

                        Comment


                          #13
                          I couldnít disagree more with you George, but to each his own
                          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.

                          Comment


                            #14
                            Hi...if you are wiring a car that did not have a factory amp, you'll have 4 twisted pairs that run to or near the head unit location. Sometimes you'll have to cut back the harness wrap a bit to find them. Each pair is a +/- set with the signal wire color as described above and the brown stripe wire the return ground. Wire the speakers as specified by the head unit manufacturer.

                            Comment

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