Radio upgrades for dummies

[SRR2]

Ok, I know quite a few of you guys have upgraded the stock radio to something a lot more up to date. So I know it's possible. Now, I have this '91 iX that uses the same radio -- Pioneer KE-83ZBM --



that came standard in the '89 535 I used to have. And, it has that bizarre proprietary connector block on the back.

So here's my question: what the heck do I have to do to install something newer in there? I looked at Crutchfield and they list a couple of dozen 'compatible' radios, and they say I need two things: a BMW receiver harness - http://www.crutchfield.com/S-Sv42hfj...sp?i=120709195 and a PAC OEM-2 gizmo - http://www.crutchfield.com/S-Sv42hfj....asp?i=127OEM2

This doesn't make sense to me. Why would I need that harness adapter? Does it plug into the existing car's harness and mate up with the OEM-2? That is, you'd assemble the adapter and OEM-2 on your workbench by crimping wire to wire, and then the RCA plugs connect to the new radio?

Or, on the other hand, would the OEM-2 just connect to the harness in the car after you cut off the old connector block?

Or, does the OEM-2 mount in the trunk next to the amp?

Second issue: how do these new radios mount to the existing panel? I'd be willing to bet that they don't have pentagonal socket head screws that expand ears into the frame. I'm after a maximally pain-free upgrade process. Nothing fancy here, just something to slide in there and use the existing amps and speakers.

I really need help here guys. This is the wife's car and it's not working. It ate a tape and now it thinks there's a tape in there, but there isn't, so there's no radio function either. This is rapidly becoming a household priority. I'll be most appreciative to anyone who can spell this out for me.

[uscharalph]

Ok, I know quite a few of you guys have upgraded the stock radio to something a lot more up to date. So I know it's possible. Now, I have this '91 iX that uses the same radio -- Pioneer KE-83ZBM --



that came standard in the '89 535 I used to have. And, it has that bizarre proprietary connector block on the back.

So here's my question: what the heck do I have to do to install something newer in there? I looked at Crutchfield and they list a couple of dozen 'compatible' radios, and they say I need two things: a BMW receiver harness - http://www.crutchfield.com/S-Sv42hfj...sp?i=120709195 and a PAC OEM-2 gizmo - http://www.crutchfield.com/S-Sv42hfj....asp?i=127OEM2

This doesn't make sense to me. Why would I need that harness adapter? Does it plug into the existing car's harness and mate up with the OEM-2? That is, you'd assemble the adapter and OEM-2 on your workbench by crimping wire to wire, and then the RCA plugs connect to the new radio?

Or, on the other hand, would the OEM-2 just connect to the harness in the car after you cut off the old connector block?

Or, does the OEM-2 mount in the trunk next to the amp?

Second issue: how do these new radios mount to the existing panel? I'd be willing to bet that they don't have pentagonal socket head screws that expand ears into the frame. I'm after a maximally pain-free upgrade process. Nothing fancy here, just something to slide in there and use the existing amps and speakers.

I really need help here guys. This is the wife's car and it's not working. It ate a tape and now it thinks there's a tape in there, but there isn't, so there's no radio function either. This is rapidly becoming a household priority. I'll be most appreciative to anyone who can spell this out for me.

I like my Pioneer KE-83ZBM now that I've got the cd player that is the right connect to it. I even bought another one on eBay as a backup.

[Badkrma]

I am looking for a working KE-83zbm as a backup. The LCD panal just went out on mine.

[jdt10768]

Buy stuff at Crutchfield. Take said stuff to stereo place. They install stuff. 40$. done.

[632 Regal]

now were talking!

Buy stuff at Crutchfield. Take said stuff to stereo place. They install stuff. 40$. done.

[dacoyote]

now were talking!

You know.. there is this guy on ebay that does some killer xm radio installs that look really pro....

:-)

-Charles

[SRR2]

After more hours of research, I have some of the answers.

New headunits have differential power outputs. IOW, there are two wires to each channel. One wire has + signal, the other -signal. It's an easy way to double the voltage output and quadruple the output power for a given supply rail voltage. The downside of this is that each channel has to have twice as many output devices in the amplifier and there are twice as many conductors to run to the speakers.

The old BMW headunits have single-ended (ground-referenced) power outputs. IOW, there's only a single wire carrying the signal to the speakers and they rely on chassis ground for the return. This is a low cost approach. To raise the power levels in the premium audio setups, they added in an amplifier mounted in the trunk. So instead of the power outputs of the headunit driving the speakers directly, they drive the power amplifier's inputs at a fairly high voltage level. This is why you'll see complaints about the BMW amps being unsuitable for use with preamp outputs from headunits or from accessory signal sources. They need fairly high signal input voltage levels to operate. I haven't confirmed whether these amps have single-ended or differential outputs to the speakers. I suspect that they're still single ended for wiring simplicity and consistency with non-amplified applications, but I don't know. Anyone who's replaced any of the factory speakers should be able to help out here. If it's single-ended, one terminal of the speaker will be connected to ground in the vicinity of the speaker. If it's differential, there will be a pair of wires from the amp to each speaker.

So to use a modern headunit with differential power outputs, there has to be a way to adapt differential to single-ended. Under ordinary conditions, it should be possible to drive the BMW amp with one of the two power outputs for each channel. Arbitrarily, you'd probably use the '+' designated lead, but in reality as long as you use all four of the same, it makes no difference which you choose. The ramifications of this are simple: by using a single lead, you artificially designate ground as the signal return line. Under best case conditions, this should work OK, but in practice the success of doing this will depend on some of the design choices made by the headunit manufacturer, especially whether they've used 'power/chassis ground' as the internal reference point for the power amps. They might have done this, they might not. Unless you have the unit in hand, you won't be able to tell until it's too late and installed in the car. If they elected to use 'ground', then all will be well. If they elected to float the amp outputs off ground, as they might if they'd included a secondary power supply to run the output power stage, then you will likely run into a noise problem of some degree, ranging from barely audible to completely unworkable.

Here's where the OEM-2 comes in. It contains circuitry that converts the differential power outputs to single-ended/ground referenced that passes the signal, but isolates the ground. To mate up with the BMW standard wiring, this adapter needs to be located at the headunit. This adapter does a couple of other functions, but for this application, this is the important one.

So basically what I'm left with is some minor wiring of the connector adapter to the OEM-2 on the bench, stuffing these two items in the dash, connecting the new headunit to the adapter, and shoving it all in the panel, hoping that there's room behind there for it all to fit. It would have been nice had the manufacturers of the headunits given their dimensions, but it seems that none do. But enough people have done this mod already that it probably fits somehow.

So, with any luck in a week or so I'll have a new CD system that plays CD/CDR/CDRW media containing CDA/WMA/MP3 audio. Nice to have MP3 capability because it effectively eliminates the need for the cost and complexity of the changer.

One last note for anyone else interested in MP3 capable players. Not all of them handle VBR MP3s! The Pioneer I chose does, but many others I looked into had either no known functionalty or warnings about possibly erratic operation. The only way you're going to discover this is to access the manufacturer's site and read the user manual -- I didn't find this detail at any retailer's site. If there isn't one available, the safest thing would be to avoid that unit.

[SRR2]

The radio upgrade is complete and working. Here are a couple of notes and observations to address most of the issues in accomplishing it. I bought a Pioneer HU so these comments will apply to that. Naturally YMMV with a different manufacturer.

NOTE: before you do any of this, disconnect the negative lead from the battery. You will have live +12 exposed while working on the wiring and it can cause damage, or at least a blown fuse, if it contacts something it shouldn't while you're working on it.

1. Mounting. I haven't installed a radio in a car for 20 years maybe and didn't know what to expect with this. Actually it's pretty easy. There's a DIN-sized sleeve that slips into the existing opening and is anchored by bending ears out of the sleeve to clamp onto the mounting surface. It's not elegant but it seems to work well enough. The HU itself slips into the sleeve and locks in there with two tabs. They give you two 'keys' that slip in alonside the HU to unlock it and slide it out.

2. This HU uses fixed panel lighting. It's not easy to find out about lighting from many manufacturers, I've discovered. Data sheets and product brochures mostly avoid the subject. Therefore, there's no use for the panel lighting wiring from the old radio. Some expensive HUs, like Nakamichi, have variable intensity, variable color lighting. I don't know how well this mates up with the lighting power in the car. It wasn't obvious to me how the lighting worked in the E30 -- the variation on the lighting wire was much smaller than I'd expected. I don't know what technology (variable voltage drive, pulse-width modulation, something else?) that the E34 uses.

3. Electrical. Lots of people, including Crutchfield, claim that an output adapter is required to permit the HU to work with the BMW trunk mounted amplifier. In the case of the Pioneer, this is not true, however, I can't say how well this will hold with another manufacturer. You'd have to make a temporary connection and try it out.

As I mentioned in the previous post, the problem lies in mating the differential power outputs of the HU to the single-ended amplifier inputs. I simply clipped back and tied up the "-" power outputs of the four channels. (NEVER ground these "-" outputs!) The "+" outputs connected directly to the existing wiring for the four channels that go to the amp. The HU (again in Pio's case) uses a ground reference in the amplifier design so there was no problem with spurious common mode noises, and the installation was dead quiet under all operating conditions. Quieter, in fact, than with the factory HU. This HU was rated at "50 watts" (which is mostly marketing hogwash -- the real output is probably more like 10-15w in differential mode) which, when using only the "+" half of the output drive, works out to a maximum ~5v signal level which looks like a nearly perfect level to drive the amp in the trunk.

Power to the HU is easy too. There's the battery +12 and the switched +12 that mate up 1:1 with the corresponding HU inputs.

The "remote output" of the HU that's used to switch on the amp and to raise the antenna (this is a late E30 3-series, but the audio system is the same as on the early E34s) also mates up 1:1 with the harness. The Pio specifies a maximum current draw on that line of 300ma. The antenna and amp combined draw 75ma.

4. "Old Style Wiring". This diagram

shows most of the wiring. It's incomplete and vague on a couple of connections along the left side of the picture. There are five connections, from top to bottom, two in a large two-pin header, a single push-on terminal, and then two in a small two-pin header. The functions, from top to bottom are 1) vio/blue +12v switched from the ignition 2) brn/blk low voltage driven from panel light dimmer, 3) wht +12v output switched by the HU on/off to drive external amp and antenna controls, 4) wht +12v switched on with the panel lights, 0v when lights off, 5) yel +12v always-on battery connection. The speaker designations on the diagram are correct.

This information ought to be all you need to do your own installation. Had I not needed to do all the experimentation, the whole operation would have taken well under an hour. Newer, ~1991 and later, E34s have the improved single-block radio connector making this job easier since the adapters for this are readily available.

[Mendozart]

What Pioneer model did you use?

[SRR2]

DEH-P4700MP. It's a little on the glitzy side, but arguably one of the better of a bad lot. You have to get into $800 Nakamichis to find panels that look compatible with the original radio. I can tell you that the performance of the AM and FM tuners is *FAR* better than the original 1987 vintage Pioneer. There are at least twice as many useable stations than the old radio would pull in. And it plays MP3s which is what my wife got all excited about. That's as good as having a 10-disk changer. All for a price lower than getting the original radio repaired.