Understanding E30 speaker and amp wiring

[bradnic]

The OEM left door tweeter pod has just gone NLA. sigh.
The good news: you can retrofit aftermarket component speakers and use excellent reproduction pods. My favorite is from timbershift on eBay - also available on my site.

Timbershift tweeter pods

[bradnic]

My Car doesn't have a Fader!

then you'll have to fix that. your PO chopped it off, probably from reading Luke's wiring thread. Hundreds of cars out there with hacked wiring, maybe thousands.

As mentioned yesterday, your choice is clear

The 5 item list above is what you need. If you absolutely insist on leaving your manual amp bypass in place, then yes you can go old school and rewire things, cut more of the harness, add the 17 pin connector etc. It was done that way for more than 10 years. It will work.

choice 1: wire it all up manually
choice 2: restore the wiring and use a wiring kit.

Give me a call. you have my number. If you prefer to just manual wire everything I'll refund your wiring kit.

[petercory]

My Car doesn't have a Fader! I have (4) Ground Wires, (2) ea. Blue/Brown & Yellow/Brown that terminate at the Radio Connector Plug.

[bradnic]

I have ordered your conversion kit and I will re-install the Amp Plug over the weekend.

Hi Peter

Order confirmed thanks! Have already emailed you.

Am I correct in assuming that nothing else will be required to install the CD43 Business CD.

The 5 requirements were posted earlier:

A few things are required to run a CD43 in standalone config in a late model E30 without cutting OEM wiring

1. unmodified sound system wiring
2. a trunk amp connector adapter
3. replacement front wiring
4. a matching rear channel adapter
5. a 17 pin connector adapter connected to 1, 3 and 4 above.

This would defintiely go easier if you can share some pics of the radio wiring.

• You need to repair the trunk amp connector pigtail you removed. As mentioned previously, match wire colors, use heat shrink and non-insulated butt connectors to keep the wiring profile close to the original wire size.
• If you've done any wire cutting on the radio end you ABSOLUTELY need to repair that as well.
• You *must* have a fader socket to use my wiring kit, and all the original wiring splices should be present or you won't have sound out of whichever speaker has its ground disconnected on the radio end.

For reference, this is a stock late model premium radio wiring setup (nice pic from Luke's original wiring thread).

Additionally, will I original E30 Speaker Grounds to the CD43 Business CD 17 Pin Connector plug or do the Speaker Grounds remain isolated?

When you say speaker grounds, you are actually referring to the radio output grounds between the radio and the trunk amp. Speaker grounds are NOT connected to the radio in a sound system car.

There are 4 radio output grounds near the fader connector on a late model sound system harness

• two yellow/brown stripe wires (Front L and Rear L) spliced together near the fader, with a brown wire also spliced in that connects to the radio case ground (heatsink bolt)
• two blue/brown stripe wires (FR and RR) spliced together near the fader, also with a spliced brown wire to the radio. The brown wires above are twisted together.
• The two brown case ground wires are clearly seen in the center of the pic above.

This is from BMW's engineering drawings with some notes I added. It shows the splice locations for the radio output grounds on the radio end.

[petercory]

I have ordered your conversion kit and I will re-install the Amp Plug over the weekend. Am I correct in assuming that nothing else will be required to install the CD43 Business CD. Additionally, will the original E30 Speaker Grounds remain isolated or will they be attached to to the appropriate pin of the CD43 Business CD 17 Pin Connector plug?

[bradnic]

A few things are required to run a CD43 in standalone config in a late model E30 without cutting OEM wiring

1. unmodified sound system wiring
2. a trunk amp connector adapter
3. replacement front wiring
4. a matching rear channel adapter
5. a 17 pin connector adapter connected to 1, 3 and 4 above.

This is the wiring kit to run an E36 or aftermarket radio in a sound system car. There are multiple options for it including type of radio, external amp and sub. The wiring in the kit is different depending on the options selected.

https://oemhifi.com/products/sound-system-radio-only-conversion-kit-for-aftermarket-radios?_pos=1&_sid=551d9ed14&_ss=r

Pics are still being updated for the various options (it's alot of work).

[bradnic]

I get this has gotten complicated. I'll answer the rest of your questions below, but please contact me at bradnic@oemhifi.com and we'll get you sorted out.

I have removed the Factory Amp and have completed the Amp Delete properly.

In order to use one of my no-cut wiring kits you will need to remove the manual bypass you did and restore the trunk amp connector wiring back to stock. Unfortunately, if you did an amp bypass the way that's shown in the first few posts of this thread, then you have disabled the trunk amp connector. You're also after all that still stuck with common radio output ground wiring at the radio end.

A 1990 has the late model twisted pair radio output and speaker wiring. The four radio output grounds are spliced together a few inches from the trunk amp connector, and in several places past the fader on the radio side. The 'classic' manual trunk amp bypass used with a late model harness has you find those splices and cut the radio output ground wires out of them. it's a real hack job, not something I'd ever recommend doing to a 35+ year old car - no matter how common the practice used to be.

I have no intention of installing another external Amp. I simply am trying to install a stand alone CD43 Business CD using the existing E30 Premium Sound Speakers and if possible, using the factory wiring.

Yup, that's a reasonable goal if you want to use a CD43 CD radio with enough internal amp power to run without an external amp. The CD doesn't support MP3s or track info, but it's right there in the dash.

A few things are required to run a CD43 in standalone config in a late model E30 without cutting OEM wiring

1. unmodified sound system wiring
2. a trunk amp connector adapter
3. replacement front wiring
4. a matching rear channel adapter
5. a 17 pin connector adapter connected to 1, 3 and 4 above.

IF I interpret Luke's comment re the correctly, he recommends attaching the 4 speaker grounds to the housing of the CD43. However I also understand that an external ground should also be attached to the CD43 Housing, should the external ground create any problems?

You need to be very careful interpreting 10 year old quotes like that. He was explaining how to connect the radio outputs to a line output converter using RCA connectors. The LOCs he was describing accept VERY high voltages as inputs - much more than a typical amplifier can handle. He's using one "side" of each radio output for the RCA positive, and then grounding the RCA plug to the radio case / chassis, NOT the radio output negative which must NOT be grounded. You won't get full power with that setup as explained in my previous post (to be verified).

Speaker grounds, radio output grounds and chassis grounds can all be different - and incompatible - things depending on the setup.

As an alternative can I simply bypass the "Factory Speaker Wires" completely and run new + & - leads from the CD43 17 pin connector to the (2) Existing E30 rear speakers and properly Ground the CD43 Head unit? Additionally, i understand that it will be necessary to rewire the front Speakers and Tweeters in order for them to function when connected directly to the CD43 Business CD 17 Pin Connector. If you have a wiring kit to do this, I would like to purchase it, how can I do so.

The 5 item list above is what you need. If you absolutely insist on leaving your manual amp bypass in place, then yes you can go old school and rewire things, cut more of the harness, add the 17 pin connector etc. It was done that way for more than 10 years. It will work.

Lastly, I have the factory Amp Complete with the plug with about 8" of original wiring in tact, is it of any7 interest to you; I understand that it was a new factory replacement installed about 12 years ago.

Yes interested. Please drop me a note.

[petercory]

I have removed the Factory Amp and have completed the Amp Delete properly. I have no intention of installing another external Amp. I simply am trying to install a stand alone CD43 Business CD using the existing E30 Premium Sound Speakers and if possible, using the factory wiring.

IF I interpret Luke's comment re the correctly, he recommends attaching the 4 speaker grounds to the housing of the CD43. However I also understand that an external ground should also be attached to the CD43 Housing, should the external ground create any problems?

As an alternative can I simply bypass the "Factory Speaker Wires" completely and run new + & - leads from the CD43 17 pin connector to the (2) Existing E30 rear speakers and properly Ground the CD43 Head unit?

Additionally, i understand that it will be necessary to rewire the front Speakers and Tweeters in order for them to function when connected directly to the CD43 Business CD 17 Pin Connector. If you have a wiring kit to do this, I would like to purchase it, how can I do so.

Lastly, I have the factory Amp Complete with the plug with about 8" of original wiring in tact, is it of any7 interest to you; I understand that it was a new factory replacement installed about 12 years ago.

[bradnic]

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

There's alot of confusion about this out there. It's one of those things that should be verified in testing. I have not done this yet, because it should be tested with multiple types of radios and wiring setups.

I did notice that Luke posted this on the CD43 thread I referenced above

Pierre, you will use the speaker + to the center pin of the RCA, and then use chassis ground on the outer shield.

Do not use the speaker - from the deck at all.

I assume that's where you got your 3rd option. You would think an amp with differential outputs would output HALF the power if you wired it that way, since you're effectively running in "single-ended" mode when you do that. There's a DC offset that gets filtered out, so that shouldn't factor here. Clearly folks were leaving the speaker negatives disconnected back then, and the original Sound System radio wiring didn't use the radio output negatives either.

This is definitely an example of "not verified" info.

[petercory]

If I understand you correctly, since I have done the Amplifier bypass and do not plan on adding another stand alone amplifier, it will be necessary to bypass the existing wiring to the rear speakers and run new + & - leads from the 17 pin connector to the (2) rear speakers. Will your Kit allow me to connect the front Speakers and Tweeters to the 17 Pin Connector; if so, what is the cost of the Kit and how do I place an order for the Kit?

[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.

[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?

[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

[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.

[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). With the exception of radio only 318is wiring, 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.