Understanding E30 speaker and amp wiring

[petercory]

I'm Installing a CD43 Business CD in a '90 Convert W/Premium Sound. I've removed the Amp & completed the Bypass. Do I connect the (4) Speaker Ground Wires coming from the Speakers together or tape them off individually. I know that they do not get connected to the head unit.

[marcopoloindependent]

Thank you bradnic. I see you have made some adapters. You haven't happened to make an adapter to go from the E30 harness plug to an E36 amp? I'm sure I have an E36 amp somewhere. Or an adapter to jump the connectors in the E30 Amp plug to bypass the amp?

[bradnic]

Im trying to understand which OEM HiFi harness I need for my project. I have an 87 coupe with the trunk amp and 2 channel fader.

Ok that factory harness has a single shared ground wire for all the output channels from the fader connector.

• 2 radio positives and 1 radio output ground come from the radio to the fader socket,
• 4 positives and 1 shared ground route from the fader socket to the trunk amp.
• From there 2 wires per channel are sent to the speakers, but they are not twisted pairs.

It is common to have feedback issues due to the front and rear ground points in the car needing cleaning and tightening.

I’m planning to install a new head unit and powering the speakers form that directly.

So you are converting to a 'radio only' install.

Radio-only aftermarket radio:
You didn't say, but I assume you are talking about an aftermarket radio with more power built in. Most aftermarket radios use class D amps that REQUIRE individual radio output ground wires. This means you cannot use the 5 factory radio output wires in your car. Folks have been tearing the factory radio wiring up for decades to get around this, which is really unfortunate.

I have a no-cut workaround for this which is an aftermarket radio kit that provides a couple of adapters and replacement front kick panel wiring. One of the adapters connects to the trunk amp connector, the other provides the missing radio rear channel wiring from the fader socket. You can even have a radio-specific adapter as well depending on the model you're using.

Radio-only OEM+ radio:
It's more expensive, but if you wanted to stay OEM customers have installed CM5908s with Amp+ in radio only mode in cars with this harness setup using my wiring kits. That gets them 30 watts per channel directly from an OEM radio with BT, pre-outs, sub-outs and 5 band EQ.

I already replaced my rears as they literally disintegrated, and will be replacing the fronts as well. PO replaced these speakers over a decade ago, so I no longer have the original speakers.

See previous posts where I get into aftermarket component speaker options. For convertibles there's a also coaxial upgrade option for the tweeter less standard factory speakers in the rear.

My question is, will the bypass only harness work, or do I need the version that includes the speaker wires as well, or will the factory wires work with the bypass only adapter?

The wiring kits in both options above (aftermarket and radio-only) include both a bypass adapter and a fader connector adapter. They can also include a radio adapter as well (ISO connectors, splice in your radio's pigtail etc.)

[Venik4]

Im trying to understand which OEM HiFi harness I need for my project. I have an 87 coupe with the trunk amp and 2 channel fader. I’m planning to install a new head unit and powering the speakers form that directly. I already replaced my rears as they literally disintegrated, and will be replacing the fronts as well. PO replaced these speakers over a decade ago, so I no longer have the original speakers. My question is, will the bypass only harness work, or do I need the version that includes the speaker wires as well, or will the factory wires work with the bypass only adapter?

[bradnic]

Excellent post you started bradnic!

Glad you have found it useful!

I need to finally finish a complete E30 1989 325is audio system install into my 1971 BMW 2002 (50 year ownership) that I started 2 decades ago. The only upgrade is a CD43 head unit. The problem I have is audio clipping especially when playing a high quallity CD. I have tested 3 different OE audio amps with no change. I will locate another CD43 to test but maybe the CD43 is over powering the OE speaker/tweeters? PS I am working on some custom from kick panel mounts for the front speakers.

The CD43 was an E36 area radio that worked with a different power amplifier than what was used in the E30. It definitely produces about double the power than the E30 radios did, so you are probably correct that it is overloading the amplifier. I recommend you run an E36 amplifier or run the radio without an amplifier.

This post about the CD43 is excellent

https://www.bimmerforums.com/forum/showthread.php?1458105-CD43-Head-Unit-amp-Audio-Amp-Fundamentals-A-Primer-LONG

[marcopoloindependent]

Excellent post you started bradnic! I need to finally finish a complete E30 1989 325is audio system install into my 1971 BMW 2002 (50 year ownership) that I started 2 decades ago. The only upgrade is a CD43 head unit. The problem I have is audio clipping especially when playing a high quallity CD. I have tested 3 different OE audio amps with no change. I will locate another CD43 to test but maybe the CD43 is over powering the OE speaker/tweeters? PS I am working on some custom from kick panel mounts for the front speakers.

[bradnic]

I just purchased OEM/factory/stock door tweeter speakers and am interested in installing them. I see the wiring for them in my side door mirror panels and read online that these are plug-and-play since the OEM/factory ones have a crossover and capacitor built in. (see these articles here and here). Is that true?

To answer the premium tweeter retrofit question directly, from an OEM / OEM+ perspective, meaning no wire cutting:

1) CROSSOVERS ARE MANDATORY TO DRIVE THE TWEETERS.
I would not recommend the advice in either of the links you posted. They're not necessarily harmful, but they're not OEM+ either.

The OEM premium / Sound System speaker setup included a 6db/octave passive crossover wired on the back of each kick panel speaker (a "high pass filter" consisting of a coil and capacitor, tuned to about 3khz or so).

This pic shows an original sound system kick panel speaker and the two tweeter connections coming from the tweeter pods (more on that below)


Amazingly, you can still buy those mid-bass drivers new. The same Sound System mid-bass driver is used in the kick panel and rear package tray (for coupes and sedans).

OEM BMW mid bass driver 65-13-1-386-546 https://www.ecstuning.com/b-genuine-...h/65131386546/

Alternatively, you can retrofit aftermarket component speakers as well. Component speakers come with more advanced aftermarket crossovers, usually 12db per octave (i.e. steeper ramp off of low frequencies) with adjustable tweeter levels. The two I recommend are listed below. The Morels are about $50 a corner more, have soft dome tweeters and 110W RMS power handling. Either are a great choice.

Morel 502 Tempo Ultra MkII https://www.crutchfield.com/p_210TU5...-502-MKII.html
Focal 130AS https://www.crutchfield.com/p_091130...nce-130AS.html

If you go aftermarket, you will need to swap the OEM tweeters out if you buy those, or just order some high quality aftermarket tweeter pods
Timbershift tweeter pods are excellent and reasonably priced https://www.ebay.com/itm/165481300510

2) All E30S (AT LEAST IN USDM) INCLUDE THE DOOR WIRING FOR DOOR TWEETERS
Just pop the tweeter pod blank on a radio only car and you'll find grey/green and grey/yellow wires behind it.

3) UNFORTUNATELY RADIO ONLY CARS DO NOT HAVE THE MATING FRONT TWEETER GROUND CONNECTOR IN THE MAIN WIRING.
See the earlier pic showing the connections coming from the tweeter pods. The white connector has a large female spade terminal connected to a grey green wire. This is the tweeter positive and gets connected to the Sound System kick panel speaker. The blue connector is the tweeter ground, which connects to a mating blue connector that is part of the Sound System factory wiring harness. Since that harness is not present in a radio only car, an adapter is needed to connect the tweeter ground to the kick panel speaker. I a couple of versions of these available on my site (or just send me an email)

Sound system wiring showing the missing blue tweeter ground mating connector . pic in the center shows the car's tweeter wiring connected to the premium harness and kick panel speaker.


Unmodified radio only wiring in the kick panel area on my 86 325. You can see the kick panel speaker wires (yellow/brown and yellow/red, pulled from behind the kick panel opening), and both tweeter door wires, positive (grey/green with white connector) and tweeter ground (grey/yellow with blue connector)


4) for folks wanting the OEM front tweeter pods, they're also still available new, 65-13-1-377-687 and 65-13-1-377-688

The rear standalone tweeter is 65-13-1-377-772, unfortunately NLA but available used

5) REAR PREMIUM SPEAKER UPGRADE OPTIONS
The two Sound System retrofit choices available to someone with a radio only E30:
- add coaxial speakers to the rear package tray (or the rear quarter trim on convertibles
- for coupes and sedans, source the rear speaker housings. These can be easily painted to match your interior.

[JovialToast82]

pls drop me an email and I’ll be happy to assist.
bradnic@oemhifi.com

Thanks, Brad. I'll send you an email.

[bradnic]

Hi all - I have a 1989 (manufactured in 10/88) BMW 325i coupe with base model speakers (in the footpanels + two in the rear behind the rear seats) and the stock 2 channel Pioneer KE81 radio -- no amp in my car as far as I know. I just purchased OEM/factory/stock door tweeter speakers and am interested in installing them. I see the wiring for them in my side door mirror panels and read online that these are plug-and-play since the OEM/factory ones have a crossover and capacitor built in. (see these articles here and here). Is that true? Will they work and automatically filter out the mid and low frequencies or do I need to do anything different to make them work?

Separately, my stock 2 channel Pioneer KE81 radio is broken and I am interrested in replacing it with a BMW Reverse RDS radio from bmwradios.com. Does anyone know if this Reverse RDS radio will work with the door tweeter speakers without any re-wiring work or other modifications? And whether I should be ordering a 2-channel adapter for the radio or a 4-channel radio adapter?

I know almost nothing about car audio so would appreciate any help/guidance. Thanks!

pls drop me an email and I’ll be happy to assist.
bradnic@oemhifi.com

[JovialToast82]

Hi all - I have a 1989 (manufactured in 10/88) BMW 325i coupe with base model speakers (in the footpanels + two in the rear behind the rear seats) and the stock 2 channel Pioneer KE81 radio -- no amp in my car as far as I know. I just purchased OEM/factory/stock door tweeter speakers and am interested in installing them. I see the wiring for them in my side door mirror panels and read online that these are plug-and-play since the OEM/factory ones have a crossover and capacitor built in. (see these articles here and here). Is that true? Will they work and automatically filter out the mid and low frequencies or do I need to do anything different to make them work?

Separately, my stock 2 channel Pioneer KE81 radio is broken and I am interrested in replacing it with a BMW Reverse RDS radio from bmwradios.com. Does anyone know if this Reverse RDS radio will work with the door tweeter speakers without any re-wiring work or other modifications? And whether I should be ordering a 2-channel adapter for the radio or a 4-channel radio adapter?

I know almost nothing about car audio so would appreciate any help/guidance. Thanks!

[strickland]

Thanks so much! I will email you for more detail.

yes I have the fader wheel under the air vents. It seems to create a lot of static. I’ve tried replacing it with a bunch of used fader knobs but the result is still static-y. I’d like to delete it.

[bradnic]

Hello!

First of all, bradnic you rock! I am also a diy’er who knows his way around the E30, but I’m a total rookie in regards to audio. Glad to gave found a specialist. My setup & questions follow…

glad you found the info helpful! Lots of work went into this. Some brief answers below, but please reach out via bradnic@oemhifi.com to discuss things in depth.

I have an 89 coupe with premium sound. I assume it’s the 4 channel late model. (How do I confirm this?)

depends on your car’s build date. BMW cut over to 4 channel wiring in late 89. If you have a fader below your center ac vents then you most likely have the 2 channel non-twisted pair wiring with a single shared radio output ground.

I’m thinking about replacing the oem amp with your refurbished amp. Then I can keep my oem wiring in the trunk, correct? Just plug & play? No need to replace that pigtail?

completely plug and play, as are all my wiring products. Respect the OEM design - NEVER cut your factory wiring!

I’m also wondering if I could / should add a small active sub to the stock setup? I found a simple RCA line output converter, but not sure where to connect it. Is it better to splice in the RCA from the headunit side, or the trunk amp?

super easy to do this with a Sound System setup. I have adapter harness options for sub setups as well. If you use a small powered sub like the Alpine PWE-S8 I have adapters that allow you to power it right from the trunk amp connector, no wire cutting.

I have an older aftermarket headunit with pigtail (no rca out). Not OEM but I would like to keep the headunit. Should that be rebuilt too?

drop me an email and we can discuss

[strickland]

Hello!

First of all, bradnic you rock! I am also a diy’er who knows his way around the E30, but I’m a total rookie in regards to audio. Glad to gave found a specialist. My setup & questions follow…

I have an 89 coupe with premium sound. I assume it’s the 4 channel late model. (How do I confirm this?)

I’m thinking about replacing the oem amp with your refurbished amp. Then I can keep my oem wiring in the trunk, correct? Just plug & play? No need to replace that pigtail?

I’m also wondering if I could / should add a small active sub to the stock setup? I found a simple RCA line output converter, but not sure where to connect it. Is it better to splice in the RCA from the headunit side, or the trunk amp?

I have an older aftermarket headunit with pigtail (no rca out). Not OEM but I would like to keep the headunit. Should that be rebuilt too?

Thanks in advance!!!

[bradnic]

So I should not be using the 719 for my early model coupe? What harness should I be looking for then?

as I wrote earlier, you want the twisted pair version of the 719 harness for a coupe or sedan.

Yeah, I'm aware I'm gonna be losing out on quality but that doesn't bother me at all. As I said earlier, I'm not an audiophile. I simply just want to hear the music and use the OEM system. I was born in the early 2ks so using older stuff like this is interesting and fun for me because it was never a norm throughout my life. I'll be using a 3 head deck for recording tapes but will also be using tapes of albums made by artists.

love it!

[B2NTY]

Welcome to R3V!

Thank you! I've been a lurker on the forums for a while but I'm happy to be a participating member.

If you haven't already done so, get your radio and amp rebuilt. The amps have a 100% failure rate in my experience, even if they haven't been used. 30+ year old radios also need rebuilds and tape maintenance if you plan to keep that.

I think I'd be happy to try and take on the rebuild of them. I've built computers and worked with soldering quite a bit when I was a kid. Would you happen to know anywhere I could find some instructions on rebuilds for the amp and cm5908 and also parts for it?

YOU DON'T NEED AFTERMARKET WIRING UNLESS YOU'RE RUNNING A SUB OR EXTREMELY HIGH POWER LEVELS
Unfortunately there are literally hundreds, maybe even low thousands of E30s out there with butchered audio wiring. These cars are all classics now, so continuing that practice is certainly not a good idea. When it comes to stock audio wiring, I personally let basic electrical engineering and "OEM+" guide my thinking. You also need to be clear on what your audio goals are, but I can say flat out that there is absolutely NO engineering driven reason to cut the factory audio wiring, PERIOD. I do know folks that just won't accept that statement, but I stand by it.

Those that insist on aftermarket wiring often have the idea that you need very heavy gauge wiring to run power to the speakers. Unless you're running over 150 watts to EACH CORNER of the car, it's just not true, and even then, the only physical effect from running that much power through the wires is a slight temperature rise, maybe 1-3 degrees. Note I DID NOT include power wiring in this discussion. That's a completely different conversation, especially if you intend to run a trunk sub or high powered radio of some sort (like a 5908 with Amp+ in an install that uses the speaker output wires). But there's no stock sub wiring anyway, so it's a moot point.

I agree, it's unfortunate the amount of harnesses are butchered (including mine due to the PO), it makes it feel impossible to find an uncut one. MY GOAL IS CLEAR, I WANT TO HEAR MUSIC COMING OUT OF THE SPEAKERS AND INTO MY EARS. I'm in no way an audiophile and currently use an almost decade-old portable speaker for music in my car ATM and am fine with using even just my phone speaker.

Note: I confirmed with BMW Classic a while ago now that while both the radio only and premium audio wiring was modified to twisted pair radio outputs and speaker outputs some time in 89, the part number did not change. You don't want to use the earlier 718 and 719 wiring if you can avoid it, because it's not twisted pair, and it uses a 5 wire radio output setup, not 8.

So I should not be using the 719 for my early model coupe? What harness should I be looking for then?

LIMITATIONS OF LATE MODEL PREMIUM WIRING
Even with a late model premium harness though, there are two major limitations which require "no-cut" workarounds, both of which are solved without cutting anything:
1) the radio outputs have 'single ended', common ground wiring at the radio and amplifier ends of the harness. This is by far the biggest hassle to deal with on factory sound system wiring, as some aftermarket radios / radio upgrades require individual radio output grounds to work properly.

The workaround for this is either
(a) don't use the radio output wiring - instead use a radio with pre-outs or a harness adapter kit like the one I created for Amp+
(b) stick to stock radios or aftermarket radios that are confirmed to work properly with common ground radio outputs.

2) there is no direct connection between the radio and the speakers. So unless your sound system equipment is 100% stock you will need to use by-pass harnesses in the trunk. Again, this is a completely solved problem.

I'm going all OEM here, speakers, amp, cm5908, and I'm thinking harness now but am going to keep these in mind.

I do get that, really. But you can still scratch that itch and leave your wiring stock though the bypass harnesses and trunk sub wiring.

Yeah I keep my hands full with the itch lol. I've done a five lug swap and after I handle this I'm going to be getting ready for a 13B turbo swap. It's gonna be really painful but really fun. :,)

It is flat out NOT TRUE that the twisted pair premium stock wiring limits audio quality. The greatest limitation to OEM audio quality in these cars has always been SIGNAL SOURCE, followed by THD from the radio's internal amp and trunk amp (if you're running at high volume levels). So unfortunately this includes tapes. I totally get the absolutely legit emotional appeal of tapes (and vinyl), but even if you record with a 3 head azimuth adjusting tape deck like a Nakamichi 680ZX or a Dragon, your tape recordings will never sound as good as a high quality BT solution. It will definitely sound better recorded on a 3 head deck though.

Yeah, I'm aware I'm gonna be losing out on quality but that doesn't bother me at all. As I said earlier, I'm not an audiophile. I simply just want to hear the music and use the OEM system. I was born in the early 2ks so using older stuff like this is interesting and fun for me because it was never a norm throughout my life. I'll be using a 3 head deck for recording tapes but will also be using tapes of albums made by artists.

Thank you so much for all the info! I think I'll be going with the premium wiring harness route and sourcing one from a part out. I'll most likely be getting the OEM wiring to repair kit from Cantelope radio or OEM HIFI (which I believe is you) because I'm sure wherever I get it from it'll be gutted at the head unit. So I'm going the OEM late model premium wiring harness route and will be having a pure OEM system with a rebuild of the amp and head unit. Is there anything else I should know for/about this swap?