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Understanding E30 speaker and amp wiring

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    #31
    yeah, I wondered. I think I left it attached to the radio that I ended up selling for probably $5. Doh! I see it's still available new, I should order one before it goes NLA.

    I'd pat myself on the back, but I feel like I dodged a bullet. When I first looked at it again, I had no recollection of how I'd wired it originally and feared the worst (it was almost 20 years ago, lol). But earlier when I was even younger and especially dumber, I cut a huge hole in the hood of my '67 Dodge Dart to put in an ugly hood scoop. Ugh. I regretted it instantly, and ever since then I've had an aversion for permanent, irreversible mods.

    It's funny because of course when I originally did this, I didn't listen to tapes - I wanted a CD player, and later MP3s were the thing. The stock stereo I didn't assign any value to. Now I mostly listen to the radio, and I don't exactly blast the tunes. I've had the blank plate for nearly 10 years now, and honestly I'd be pretty happy with a stock, unmolested sound system vs nothing at all. Now I kind of want to make a mix tape of some 1990's music, lol.
    Last edited by nando; 05-03-2021, 03:57 PM.
    Build thread

    Bimmerlabs

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      #32
      Hello, am replacing the head unit on my 91 318i Converible with a Pioneer CD bluetooth unit and removed the KE83ZBM and didn't realize there was an auxiliary amp on this vehicle.
      Where is the amp located on a convertible?
      thanks in advance
      Scottie409

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        #33
        is it in the trunk next to the antenna just like a sedan? you have to pull the carpeting off the driver's side.

        also, is your KE83ZBM for sale? Does it work?
        Last edited by nando; 01-27-2022, 01:27 PM.
        Build thread

        Bimmerlabs

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          #34
          I wanted to try and help others in return and thought maybe a video could do that.

          Luke's massive original amp bypass thread helped me out a lot. So much reading! I posted over there as well in case others are looking.

          I have a 1987 325es, CM5907, premium sound, fader in dash (6 wires), and a stock amp in the trunk. Went with a Continental TR7412UB-OR, bypass stock amp/repurpose fader wires, rewire fronts/tweeters.
          Please let me know if you see something I did wrong so I can fix it!!! I am also garbage at talking while filming...so sorry in advance.

          Hope this helps someone

          https://www.youtube.com/watch?v=lXYdEnJJVnU

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            #35
            Maybe someone can help me to figure this part. I'm trying to connect stock CM5908 stereo to aftermarket amp. My late e30 had no stock amp. I'm connecting CM5908 speaker outputs to hi-level inputs on the amp and for some reason amp doesn't like it (it shuts off after a few secs). I discovered that even though CM5908 has 4 chan. 8 wire speaker outputs, all 4 speaker "-" are actually connected to the chassis ground internally in the stereo and as a result to the car ground. Could it be that the amp doesn't want to see hi-level input signal with"-" leads on every channel being grounded?

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              #36
              Originally posted by zaq123 View Post
              Maybe someone can help me to figure this part. I'm trying to connect stock CM5908 stereo to aftermarket amp. My late e30 had no stock amp. I'm connecting CM5908 speaker outputs to hi-level inputs on the amp and for some reason amp doesn't like it (it shuts off after a few secs). I discovered that even though CM5908 has 4 chan. 8 wire speaker outputs, all 4 speaker "-" are actually connected to the chassis ground internally in the stereo and as a result to the car ground. Could it be that the amp doesn't want to see hi-level input signal with"-" leads on every channel being grounded?

              figured it out. My Kicker KEY amp didn't like to be turned on by only hi-level speaker input signal from the CM5908 (one of the Amp's options where remote turn-on wire can be left taped off and dip switch set on DC). Connected amp's remote turn-on blue wire to 12V, switched the dip switch to +12V and all is good. Actually sweet little amp, fits into the Airbag ECU bracket perfectly and even mounting holes on the bracket work with a little modification). Just had to extend LF blue wires from the middle of the dash to the amp (mounted in the airbag module location, LH side of the dash), the rest of OEM wiring worked perfectly as they all go through the left side of the dash. Basically , CM5908 speaker outputs to the AMP hi-level in, AMP speaker outputs to stock wiring. AMP is only 200 W so fits perfectly for premium sound speakers without straining the amp (45W/ea.)

              https://www.kicker.com/app/manuals/47KEY2004.pdf

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                #37
                Hi, coming out from retirement to post a correction on the original post. For the picture of my car for the older 2 channel amp bypass, make sure you only connect the speaker negatives together. (the right most bundle in the picture) In my example, I had the radio ground paired up with this, which was causing my headunit to overheat and volume would eventually go down and silent after a few minutes as it heated. Youll want to remove the ground from that bundle and either cap it, or attach it to a nearby ground location.
                Current:
                1989 325i
                1988 M3
                1987 325ic
                Past:
                2001 330ci
                2001 M3

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                  #38
                  Originally posted by jhaurimn View Post
                  Hi, coming out from retirement to post a correction on the original post. For the picture of my car for the older 2 channel amp bypass, make sure you only connect the speaker negatives together. (the right most bundle in the picture) In my example, I had the radio ground paired up with this, which was causing my headunit to overheat and volume would eventually go down and silent after a few minutes as it heated. Youll want to remove the ground from that bundle and either cap it, or attach it to a nearby ground location.
                  updated the original post. need to be clear on which grounds you're talking about though - it's easy to get confused. The speaker ground connections on the actual speakers vs the radio and amp grounds. with a no-amp system the speaker grounds are the same as the output ground connections on the radio. that's not the case on a BMW SOUND SYSTEM setup with trunk amp. you can see all of this in the schematics:

                  1) in a no amp system, the speaker grounds are connected to the radio outputs, not to the radio chassis. the radio chassis itself is grounded separately.

                  2) if you have the trunk amp, the speaker grounds are connected to the amp outputs, not the amp chassis. the amp chassis is grounded separately. the radio chassis is also grounded separately, and only the positive radio outputs are used.

                  If you read the above carefully, you'll notice the speaker grounds are never grounded to the chassis directly in either setup.

                  so yes, on a BMW Sound System setup with trunk amp, keep the output ground wires from the radio separate from the amp output ground wires (which are also the speaker grounds).
                  Last edited by bradnic; 09-04-2022, 01:28 PM.
                  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


                    #39
                    Originally posted by bradnic View Post
                    2) if you have the trunk amp, the speaker grounds are connected to the amp outputs, not the amp chassis. the amp chassis is grounded separately. the radio chassis is also grounded separately, and only the positive radio outputs are used.
                    This ended up being the issue, they werent kept separate. Apologies I didnt/couldnt clarify this sooner. The car had a bad battery which I attributed the radio issues with. Turns out it was a different issue all together. Glad it wasn't worse because the heatsink on the radio got insanely hot.
                    Current:
                    1989 325i
                    1988 M3
                    1987 325ic
                    Past:
                    2001 330ci
                    2001 M3

                    Comment


                      #40
                      Originally posted by jhaurimn View Post

                      This ended up being the issue, they werent kept separate. Apologies I didnt/couldnt clarify this sooner. The car had a bad battery which I attributed the radio issues with. Turns out it was a different issue all together. Glad it wasn't worse because the heatsink on the radio got insanely hot.
                      We should all be grateful you posted your note. I made some changes to the post to clarify the above. Honestly I didn't look at it closely enough when you first sent the pic. I should have caught it then. Glad the radio is ok.
                      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


                        #41
                        bradnic/jhaurimn,

                        Can you please look at my youtube video that I posted (post #34)? https://www.youtube.com/watch?v=lXYdEnJJVnU I performed (what I thought was correct) an amp bypass/Continental HU install on my 1987 325es. Car is an early model 2 channel setup, has fader in the dash and premium sound system.

                        Everything works perfectly (HU can be used for hours) but with your recent "correction update" I am thinking I did something wrong. Looking at timestamp 7:16 in my video for reference, I simply separated the stock violet wire (ignition 12v) from the stock brown/black ground wire(s) and connected them to my new HU ISO connector accordingly.

                        My questions is this, the stock brown/black ground wire was actually 2 wires. Just like the schematic says but I didn't separate them. I just hooked it (them) up to my new HU ground wire?

                        Is this a mistake?

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