Retrofitting newer OE radios: learn from my mistake

[Jay 535i]

A while back I posted a thread asking if I could retrofit a radio from a Z3 into my E34. The unanimous reply was, "sure".

Well, it can't be done, apparently, because the newer OE radios aren't compatible with my existing amplifier, and the newer radio can't be heard without an amp. It would be prohibitively expensive to fit and wire an aftermarket amp to the newer radio.

Just so y'all know...

[Rustam]

A while back I posted a thread asking if I could retrofit a radio from a Z3 into my E34. The unanimous reply was, "sure".

Well, it can't be done, apparently, because the newer OE radios aren't compatible with my existing amplifier, and the newer radio can't be heard without an amp. It would be prohibitively expensive to fit and wire an aftermarket amp to the newer radio.

Just so y'all know...

what do you mean "aren't compatible"? in what way?

[Brandon J]

Are you sure? It might depend on the year of the radio. I know of several people who have done it and simply matched the speaker pin-outs. Does the back of the Z3 radio of flat pins or round pins. The round pins are the older version and should work.



A while back I posted a thread asking if I could retrofit a radio from a Z3 into my E34. The unanimous reply was, "sure".

Well, it can't be done, apparently, because the newer OE radios aren't compatible with my existing amplifier, and the newer radio can't be heard without an amp. It would be prohibitively expensive to fit and wire an aftermarket amp to the newer radio.

Just so y'all know...

[Jay 535i]

Hmm, it has round pins.

"Not compatible" is what the radio installation guy said. I don't know a lot about this stuff, so I have only his word to go on.

What can I tell the installer that might help him figure it out?

Edit: I spoke with the installer again, and his explanation was that the newer radio uses a floating ground while the stock amp uses a common ground (or vise versa -- I forget). Either way, they're not compatible.

Does that make sense? I don't understand this stuff very well.

[Qsilver7]

Jay, I'm can't give you instructions on how its done...but the CD43, C43, and C33 units from the Z3 and Late e36 BMWs can work in the e34 & e32.

One of the biggest hurdles for you is that your car is a 1990 model...the wiring harness is not plug-n-play in your case (you need to have a 1991-up for plug-n-play)...but others have successfully installed these radios.

Here's a link from RF where Ben installed a BMW CD43 unit into his 1988 750iL (e32): http://bimmer.roadfly.com/bmw/forums/e32/5196716-1.html

You may have to do some searching in the RF archives to find the pin outs and how to connect the wiring for e34s and e32s older than 1991 models.

Good luck.

Compatible BMW Radios:

BMW CD43 (single in-dash CD/Radio)
http://www.zakiu.com/splatch/cd43/3.jpg

BMW C43 (cassette/radio w/RDS/PTY)
http://i13.ebayimg.com/04/i/06/fb/f0/1e_1.JPG

BMW C33 (cassette/radio w/weatherBand)
http://i16.ebayimg.com/04/i/06/fe/99/7e_1.JPG

BMW Radios that AREN"T Compatible:

BMW CD53 (single in-dash CD/Radio)
http://images.snapfish.com/3457836%3B23232%7Ffp338%3Enu%3D323%3A%3E694%3E252% 3EWSNRCG%3D32333942%3A%3B954nu0mrj

[Robin-535im]

Gale has a newer 3-series radio in his e32, maybe he'll see this and post to it. I can vouch that sound does indeed come from the amp on his :)

[Jay 535i]

Thanks.

If anyone knows how it can be done, please let me know. The installer I spoke with, who seemed very knowledgeable, assured me I couldn't make it work without buying a new amp.

I do have the proper harness to fit the newer radio.

Again, the installer said that the problem was with common versus floating grounds, whatever that means.

[darron525]

what model are you trying to fit? here is an old post from George when he did the cd43 retro fit. The pictures aren't there anymore but maybe the write up will help you.
here you go:http://www.bimmer.info/forum/showthread.php?t=4998


darron

[Jay 535i]

Thanks.

Here's the radio I'm trying to fit:

http://cgi.ebay.com/ebaymotors/BMW-REVERSE-RDS-TAPE-RADIO-E30-E32-E34-E36-Z3-M3_W0QQcmdZViewItemQQcategoryZ38639QQitemZ80602494 68QQrdZ1QQsspagenameZWDVW

[gale]

I know for sure the C43 and CD43 are a direct fit in 92 and newer. Couldn't tell which model the ebay ad is for. If you can get a year that the radio was manufactured, Shogun can get you the schematic for the pin-outs. At most it would probably be a matter of re-arranging the pins in the harness socket to get it to talk to your existing amp.

[Jon K]

You can make anything work - it'd be a matter of getting the amp that would have come with the Z3 radio and making the harness match. Not that hard guys - cmon.

[Jay 535i]

But what's this about common ground versus floating ground?

[Rustam]

But what's this about common ground versus floating ground?

common ground is the body of the car - everything is connected to it hence "common"... floating ground is the connection that has potential difference between itself and the common ground, in essence, one can fit some resistance between the ground lead of the radio unit and the common ground to lower the voltage difference between power input leads of the radio.

why don't you look for schematics for hook up of this radio to see how its connected??? post it here if you find...

does the radio have a sticker or something that says how many volts amps and watts it is good for?

[joshua43214]

Floating ground is where each speaker has its own positive and negative wire from the amp or head.

Common ground is where each speaker has its own positive wire, but the ground is common for all speakers. often the speaker negative runs straight to the chassis.

Floating ground allows the amp to have separate amplifiers internaly for each speaker(channel). Common ground amps usualy have 1 amp inside that amplifies all the speakers.

hooking a floating ground head unit up to a common ground amp can damage the head, amp or both.

1990 and back e34's had common ground stereos.

What you need is a simple device that is available from dozens of car stereo outlets called a "floating ground adapter". they run about 10-50 bucks depending on how fancy you get.

The kicker here is this. you say your installer is knowledgable. Unless he is too young to have seen any older common ground systems, he should have suggested this item to you. Maybe there is something else going on as well.

[Gene in NC]

Not to hijack but is there an aftermarket radio w cd that is compatable with '89 525a, 12/88 build date?

[Qube]

Hmmmmm I installed my JVC unit myself and just tied the grounds. No problems but sounds like it's unorthodox for an 88 build year? There was no harness so a lot of wiring diagram digging and splicing...

[SRR2]

Almost anything with a DIN chassis. You will need to identify the wires going to the old radio and splice them into the new adapter plug, but that shouldn't take more than 15 minutes.

Word of advice assuming your car has the factory amp in the trunk: you will use ONLY THE "+" outputs from the head unit. Cut back and insulate the "-" outputs. Do not expect to have panel dimming on the new HU unless you buy one of the very high-end ones like Nak.

[SRR2]

What does "tied the grounds" mean?

[SRR2]

Your installer doesn't know what he's talking about.

In his lexicon, "floating ground" means that the speakers are driven differentially by dual outputs, one of them 180 deg out of phase with the other. The reason for doing this is that you can get 4X the output power with a given supply voltage.

Now here's the part he doesn't understand: Both of those outputs, the "+" and "-" are GROUND REFERENCED! Therefore you can use either one to drive the single ended (ground referenced) amp inputs on the stock BMW amplifier. Whichever you pick, + or -, use all four of them and cut back and insulate the other four. By convention, most people use the "+" outputs and cut back the "-".

[SRR2]

Search these forums. I did a couple VERY detailed posts on exactly this subject. It DOES work very well with minimal wiring. You do NOT need an adapter! You SHOULD go find an installer who knows what he's talking about.

[SRR2]

I'm sorry, but no. You don't understand "floating ground" the way it's used in car jargon. They consistently misuse the term to mean differential drive to the speakers. The HU and its amps ARE ground referenced!

You do NOT put resistors between radio ground and car chassis ground. That's a prescription for noise at the minimum or non-operation at worst.

[SRR2]

hooking a floating ground head unit up to a common ground amp can damage the head, amp or both.

1990 and back e34's had common ground stereos.

What you need is a simple device that is available from dozens of car stereo outlets called a "floating ground adapter". they run about 10-50 bucks depending on how fancy you get.

The kicker here is this. you say your installer is knowledgable. Unless he is too young to have seen any older common ground systems, he should have suggested this item to you. Maybe there is something else going on as well.

You were doing ok up until that first sentence above. Assuming that you wire the two together properly, you will not do any damage, and it will work just fine, WITHOUT AN ADAPTER. I think this adapter business was cooked up by the people that make adapters. There may be some odd circumstances where you actually need some kind of ground rereferencing, but I've never seen one and it would have to be some pretty weird design.

You are right about this installer. Young. Inexperienced.

[joshua43214]

You were doing ok up until that first sentence above. Assuming that you wire the two together properly, you will not do any damage, and it will work just fine, WITHOUT AN ADAPTER. I think this adapter business was cooked up by the people that make adapters. There may be some odd circumstances where you actually need some kind of ground rereferencing, but I've never seen one and it would have to be some pretty weird design.

You are right about this installer. Young. Inexperienced.

Cool, thanks for the correction. I always wondered if the cheap adaptors where any thing but a fancy wire splice. By reading the responses I am geussing they are. I have never used one myself, so I've never bothered to figure out how they actualy work.

[Jay 535i]

Well, the installer I took it to seemed neither young nor inexperienced, but maybe he's just lazy, or something else.

I'll try taking it elsewhere. Unfortunately this stuff is way over my head.

Many thanks everyone.

[Gearhead]

Back to the "compatible BMW Radios".... Will the CD43 work with my factory 6-disc changer allowing me to select from either the single disc or the changer? Anyone done this successfully?

Thanks!

[mkovic]

This is the standard Blaupunkt unit with RDS used in EU version BMWs. You definitely don't need separate amplifier, it has one build in.
Just not sure what good would RDS, EON and TP system do in North America. As far as I know no station there is broadcasting the RDS signal, or am I wrong?