Amplifier Wiring

[sama]

Anyone know have a wiring diagram for the amp in the back?

I'd like to rewire it to stick my own input in there, rather than the radio.

[TTTXGreg]

I just did this. Let me assemble the info/pictures and I'll post later tonite.

[sama]

hey thanks

what did you plug in? a headunit?

[TTTXGreg]

These are the plugs at the amp in the trunk. You can trace the colors from here to the radio audio outs if you need to find them up front. I put a new amp in with the OEM head unit. When I change the head, I'll run patchcords back from it to the amp and won't use the oem unshielded wires for input. saavy? Another note- notice the door and kick panel spkr share the same ground, so do the 3 spkrs in the rear enclosures(wuff/mid/tweet). If you are going to bi-amp or more, you will have to run independant grounds to all spkrs.

[8eights]

Great post, Some share the same ground on the speakers? I had to do it the hard way to install 2 sets of component speakers, Thanks!

[TTTXGreg]

I took the two plugs out of a blown OEM amp and built an adapter to plug into my aftermarket amp. I am using the OEM head for now, so all I have done is installed a newer/more power amp in the same cradle the OEM was.
I didn't want to cut that harness, this way all can be returned to OEM unblemished. And here's what that looks like-

[sama]

nice one man.

I'm doing something slightly different. Which is to remove the headunit and replace with a PC, so I need the input to the amp. it's the white wire (+12v HU on) that I was worried about most as in the E39, the amp would only go on using a pulsed ibus (10s frequancy). So the PC had to output this every 10 seconds using the ibus adaptor or the amp would go off!

Regarding the OEM wires, I think they're in a twisted pair arrangement. They were on the E39 anyway. This means although they're not sheilded, they're less likely to get interference, and they're probably wired up so that they don't run parallel to any power/rf emitting wires. I would suggest to use the OEM wires first and see if noise is an issue, before running new ones and risking getting noise. Unless you plan on really checking where all the wire looms are etc!

Thanks for the pics, I'm sure I'll be posting here again!

[TTTXGreg]

OEM harness is not twisted pair. You can find amp inputs by color at the radio from the previous picture. I just labeled them as radio outputs instead of who was FL,FR,RL,RR. Really didn't pay attention while soldering, I just plugged the rca's I soldered to the adapter after I powered everything up and faded/balanced the radio to id them. My amp gains are full down and there is still quite a bit of white noise from the radio. It's not the wiring, it's the radio. If/when I swap head units, I will run shielded patchcords for the amp inputs. The white +12 is working fine with my amp, no ibus.

[sama]

fabuolus just what I wanted to hear. thanks man

[moonfresh]

These are the plugs at the amp in the trunk. You can trace the colors from here to the radio audio outs if you need to find them up front. I put a new amp in with the OEM head unit. When I change the head, I'll run patchcords back from it to the amp and won't use the oem unshielded wires for input. saavy? Another note- notice the door and kick panel spkr share the same ground, so do the 3 spkrs in the rear enclosures(wuff/mid/tweet). If you are going to bi-amp or more, you will have to run independant grounds to all spkrs.

Hey Boss,

Which wire is it? Thanks.

[TTTXGreg]

Hey Boss,

Which wire is it? Thanks.

Ok, the white wire marked "+12v on" is hot when ignition is on.
The black plug has a constant +12v that is red/green. I would think your device needs both? Anyway- that should get you going!

[Bryson]

FWIW the e31 speaker wires are twisted pairs, I believe that they are joined to common ground just before the amp (with the exception of the rear speaker pods). Using a CD43 with the stock wiring separated into full twisted pairs and my amp gain all the way down, I have zero audible noise floor. Thank you BMW for using balanced audio wiring!

[m6bigdog]

Anyone know have a wiring diagram for the amp in the back?

I'd like to rewire it to stick my own input in there, rather than the radio.

Ok, lets not get confused.

I assume the CSi even a RHD has the late model audio system with the 10-channel audio amp with a 12-pin and a 26-pin connector.

I suggect referencing the ETM for all your wiring answers.

Download the E-31 ETM from either http://wedophones.com/BMWManualsLead.htm
or
http://shark.armchair.mb.ca/~dave/BMW/index.html

[e31yausta]

These are the plugs at the amp in the trunk. You can trace the colors from here to the radio audio outs if you need to find them up front. I put a new amp in with the OEM head unit. When I change the head, I'll run patchcords back from it to the amp and won't use the oem unshielded wires for input. saavy? Another note- notice the door and kick panel spkr share the same ground, so do the 3 spkrs in the rear enclosures(wuff/mid/tweet). If you are going to bi-amp or more, you will have to run independant grounds to all spkrs.

Seems to be a bit different than on my 94 840ci. Looking inside the trunk, the amp is located behind the left rear seat, correct? I looked at both plugs and it seems to be different wire colors compared to this picture.

[Max Lumens]

I think that 1995 was the last year for e31 wiring diagrams, so you may have trouble finding accurate info for yours if anything has changed. A reasonable place to start, if the plugs are the same, is to test the locations and correlate the wire colors. Use a voltmeter and a small speaker to see if the functions in the picture make sense and note the new wire colors.

[prit singh]

Hi Sam

That is interesting keep us posted

[TTTXGreg]

Ok, lets not get confused.

I assume the CSi even a RHD has the late model audio system with the 10-channel audio amp with a 12-pin and a 26-pin connector.

I suggect referencing the ETM for all your wiring answers.

Download the E-31 ETM from either http://wedophones.com/BMWManualsLead.htm
or
http://shark.armchair.mb.ca/~dave/BMW/index.html

That's funny, you say let's not get confused and you post a picture of a 325 wiring diagram?! My pics/wiring are from a '91-92 850. I don't see any confusion here other than you posted info on the wrong car! This is really not rocket science.

[Bryson]

That's funny, you say let's not get confused and you post a picture of a 325 wiring diagram?! My pics/wiring are from a '91-92 850. I don't see any confusion here other than you posted info on the wrong car! This is really not rocket science.

If you knew enough about the e31 wiring systems, then you would know that the late model e31 (which he is referring) is identical to the e36 3 series wiring (which he has included a picture of).

Coupled with what MaxLumens is posting that late model wiring diagrams are not available, posting the 3 series diagram is the best that is possible!

...It's not rocket science..

[cartoonz]

Bryson is correct, although without explanation someone looking at that post would likely be confused too...

[m6bigdog]

That's funny, you say let's not get confused and you post a picture of a 325 wiring diagram?! My pics/wiring are from a '91-92 850. I don't see any confusion here other than you posted info on the wrong car! This is really not rocket science.

So my reply is less confusing than rocket science.
I used the single page E-36, 10-channel amp diagram, that is identical to the E-31 amp to answer the question, 'anyone have a wiring diagram for the amp in the back' because I have yet to see a simple PDF one page 10-channel diagram with an E-31 reference.

The confusion, in North America (NA) the E-31's had two distinctly different amplifiers installed during the production years depending on the model year. Any amp wiring diagram with 2-12 pin connectors is an early model 4-channel amp that ended with model year 1993. In model year 1994, a new 10-channel amplifier was released for the NA, E-31, E-32, E-34 and E-36 series. The year model 1994, was also the first year of the CSi in NA so I assume the OP with CSi in their sig was interested in the 10-channel amp diagram.

Also, the last E-31 ETM for NA is the same one as the 1995 model year since the 1995-1997 model years 840/850 vehicles were all identical.

[TTTXGreg]

I really don't know much about these cars but if you LOOK at the picture, I am showing a 10 channel amp. Here's another tidbit- the xover is in the amp for separate tweets,mids,lows- 10 channels worth. If the wire colors differ, that's possible, but the pic is a start to verify in the car with a meter. Now again, I'm not really well versed on these 8's so I could be totally wrong. Sorry.

[cartoonz]

hate to say it but it is the cross-over that splits the 4 channel amp into 10... it is not a 10 channel amp., just looks that way with the x-over internal in the amp.

[TTTXGreg]

hate to say it but it is the cross-over that splits the 4 channel amp into 10... it is not a 10 channel amp., just looks that way with the x-over internal in the amp.

Exactly right. The idea they went to a 10 ch amp from 4 is bogus. Both are 4 ch amps w/xovers internal that feed the SAME amt of speakers. You still only have left/right and front/rear with either amp. That's 4 locations....with 10 speaker components involved.

Now to solve the confusion, there is no such thing as a 10ch amp in any of our 8's. As M6 stated correctly- the plugs are different due to different amp manufacturers. The second manu is who came up with the 10 channel bs.

[m6bigdog]

Exactly right. The idea they went to a 10 ch amp from 4 is bogus. Both are 4 ch amps w/xovers internal that feed the SAME amt of speakers. You still only have left/right and front/rear with either amp. That's 4 locations....with 10 speaker components involved.

Now to solve the confusion, there is no such thing as a 10ch amp in any of our 8's. As M6 stated correctly- the plugs are different due to different amp manufacturers. The second manu is who came up with the 10 channel bs.

Didn't you state, "I really don't know much about these cars but...".
You are correct - you need to get your facts correct so you don't post bs!

These facts are from the E-31 year change release:
"For 1994: 10x25-watt (250-watt maximum power) audio system replaces former 4x25-watt (100-watt) system; 12 speakers retained."

Therefore, It's not Bogu, bs or Magic!!
The Early model amp with the 2-12pin connectors is really a 4-channel amp (FR, FL, RR, RL) with a passive LC crossovers after the amp to drive the speakers and the 4-individual amp outputs are a single-ended amp design and that is why they can have a common ground for each channel.
The late model amp with a 12pin and 26pin connectors is really a 10 channel amp with an active/electronic crossover before the individual amp channels (3-FR, 3-FL, 2-RR, 2RL) and the late model 10-individual amp outputs are a bridge amp design where there is a + and - amp output for each channel (yep that's 2-amps per channel or 20-amps total) and the bridge design produces twice the output power of the single-ended amp design, but none of the speaker wires can be connected together or grounded..

From my knowledge of the amps with electronics as my 40 year profession and yes I've had the covers off of both the 4 and 10 channel amps. Don't believe the 25-watt per channel for the 4-channel amp - a single-ended amp with a 12-14V rail produces more like 9-watts/channel into a 4-ohm speaker. The late model bridged amp is 18-watts/channel into a 4-ohm speaker and the E-36 HK amp with the HK 2-ohm woofers gives an output power of 36-watts/channel.

[TTTXGreg]

You win, I did not know the HK was active xovers. My bad.