Understanding E30 speaker and amp wiring

[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]

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]

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]

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.