Understanding E30 speaker and amp wiring

[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!

[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]

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

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

[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.

[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]

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

[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]

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.)

[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?

[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.

[bradnic]

I'm Installing a CD43 Business CD in a '90 Convert W/Premium Sound.

Great OEM radio. Alot more power than the OEM CM5908 or KE83 your car came with, so great candidate for a radio only wiring conversion. Doesn't sit flush in an E30 dash, but there's workarounds for that.

I've removed the Amp & completed the Bypass.

It's unfortunate you cut your factory wiring. There's just no need to do that anymore to get around the "common radio output ground" issue.

STEP 1: IMPORTANT: verify your radio can work with common ground radio output ground wiring.

If it is not compatible then trying to use a common ground setup will lead to reduced power output and overheating. The workaround here is to use my OEM front harness replacements to get individual radio output grounds for the front channels without cutting your factory wiring.

Here's an E36 Sound System ETM diagram - you can very clearly see individual radio output grounds going to the trunk amplifier (lower right, BR/OR [brown / orange] wires between the radio and amplifier). The E30 Sound System setup is *NOT* like this.




STEP 2: Plug in one of my amp bypass adapters in the trunk amp harness connector

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.

The 'classic' cut amp bypass speaker grounds *are* connected to the radio output grounds. See the first post for more details. This is why you need to be certain the radio will work with common output ground wiring.

The Sound System front wiring kit with individual radio output grounds I mentioned above comes with a different version of the bypass adapter in the pic above.

[bradnic]

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?

Hi Marco

Just sent you an email about the post above.

[petercory]

The car is a '90 Conv. When I purchased the car, it had a Sony Head unit and poorly functioning Premium Sound Amp. I have Completed the Amp Bypass and the Ground Wires for all (4) Speakers still run from under the back seat up to the CD43 Business CD 17 Pin Connector but are not currently connected to it. When I removed the Sony Head Unit, the (4) Speaker Grounds were twisted/connected together adjacent to the Sony connector plug. Can you tell me if the (4) Speaker Grounds :

• Need to be attached to the CD43 Business CD Head Unit 17 Pin Connector
• Remain Twisted together and not attached to anything
• Should be taped off individually and not attached to anything

[petercory]

I just saw the addition to your earlier response. Knowing that you are a BMW Sound System Expert, can you tell me if the CD43 Business Cd will work with common output Ground Wiring? Additionally, do the front Speakers & Tweeters have to be re-wired and if so, do you offer a pre-made wiring kit for that purpose?

[bradnic]

The car is a '90 Conv. When I purchased the car, it had a Sony Head unit and poorly functioning Premium Sound Amp.

It's usually not a good idea to leave the trunk amp in place when installing an aftermarket radio, because the OEM radio was very underpowered compared to today's aftermarket units. You end up over-driving the trunk amp inputs and introducing both very high THD and clipping.

I have Completed the Amp Bypass and the Ground Wires for all (4) Speakers still run from under the back seat up to the CD43 Business CD 17 Pin Connector but are not currently connected to it. When I removed the Sony Head Unit, the (4) Speaker Grounds were twisted/connected together adjacent to the Sony connector plug.

The common radio output grounds are still there with the amp bypass folks have been doing on these cars for 20+ years. The only way to get around that is with new wiring, or better yet don't cut anything at all and use a wiring kit.

There were two Sound System harness designs, same part numbers used on both, different part numbers for coupe/sedan and convertible. I thoroughly verified all of this with BMW Classic, including review of the engineering drawings.

• the pre-89 early model harness with a single radio output ground wire between the radio and amp
• the later model harness with twisted pair radio output and amp output/speaker wires. Despite the twisted pair radio outputs, both ends of the late model harness splice the radio output grounds together a few inches from the equipment they're connected to.

Can you tell me if the (4) Speaker Grounds :

• Need to be attached to the CD43 Business CD Head Unit 17 Pin Connector
• Remain Twisted together and not attached to anything
• Should be taped off individually and not attached to anything

You always need both an output positive and an output negative from the equipment (radio only or radio+amp) to the speakers. The real question that needs answering is can the equipment you're using support the output negatives being wired together.

I just saw the addition to your earlier response. Knowing that you are a BMW Sound System Expert, can you tell me if the CD43 Business Cd will work with common output Ground Wiring?

I've certainly been doing this for a long time now, and have learned to PERSONALLY VERIFY the info I post before sharing it (or at least clearly indicate if the info is not verified). Think of it as the difference between what an engineer knows a design should do, and a technician that has direct experience with what the design is actually doing in the car.

Here's what I'm certain about:

• Unlike the E30, E36 wiring has individual radio output grounds. You can verify this yourself by (1) reviewing the ETM and (2) inspecting an E36 17 pin radio connector or amp connector. You'll see individual brown/orange wires for each channel.
• CD43 was a later model E36 era radio (99 and later on Z3 M3 and Land Rover)
• any equipment with differential outputs is incompatible with shared radio output grounds. It will produce power at reduced output, and it will overheat

I have a few C33s and C43s here in the shop, but not a CD43, so I have not personally tested the CD43. Fortunately others have.

bmwman91 did a great writeup on the CD43. It is most definitely a differential output radio. Highly recommended reading if you'd like to understand why differential outputs are used and why they need to "float", not tied to a chassis ground of any kind. His post was written FIFTEEN years ago btw.

Additionally, do the front Speakers & Tweeters have to be re-wired and if so, do you offer a pre-made wiring kit for that purpose?

Yes I certainly do. The wiring products are all based on the idea that you DON'T EVER CUT FACTORY WIRING. I'm constantly tweaking the products though as I engage with customers - there are alot of combinations to deal with depending on the original wiring, radio being run, amp config etc.

In your case, you need to convert a late model E30 sound system setup to a radio only install and a 17 pin radio connector. If you want to add something like a powered footwell sub there's an option for that too, as well as wiring adapters for component speakers should you want to head that route.