Stock stereo head unit change only : IT WORKS PERFECT !!

[BMWDriver]

I read a lot of threads and the E34 site to discover I might loose some fuctionnality (balance, fade) if I only change the stock head unit. And some cracking noises and such... Which I got after plugging all the wires per diagrams including all negative speaker wires. After trying without any negatives as suggested, that didn't do much except for faint sound 'til playing with the fade and balance.

Then I plugged in the negative right rear since nothing was coming out of it all the time almost... Amazing sound comes from my right rear speaker at last... sound also from the front that was there. But the left rear is a little deaf... so I plug in the left rear negative and BINGO !!! SUPER SOUND HEAVEN !!! (Well, I'm so frikkin' happy that's how I see it).

ALL WORKS ! Balance left to right, fade front to rear ! AND POWER ! No cracking noises whatsoever, no problems any !

YYEAAAHHH !!! I'M THE MAN !!! I'M THE MAN !!!

Now I've got to figure how to put the radio anteanna in. Splice ? Adaptor ?

[Anton CH.]

Very interesting. So did you connect all the (-) speaker wires to ground?

[BMWDriver]

Very interesting. So did you connect all the (-) speaker wires to ground?
Only the rear negatives: from the head unit rear negative to the wires for the rear negative speakers. Front negatives are capped. For reference, I plugged in an Alpine CDA-9847. All positives are plugged of course. And I did not use the RCA connections of the HU but the speaker connections of the preamp.

[Anton CH.]

Have you attempted connecting the fronts as well? It may be a good idea just to connect all four.

[BMWDriver]

Have you attempted connecting the fronts as well? It may be a good idea just to connect all four.

That was what I had done originally: all positives and negatives to their respective speaker wires. Mind you that was straight to the front negatives. But I had all sorts of problems trying to balance and fade correctly. But especially: both right speakers were just playing faint while front left was giving full power and at a fairly low volume level. Left rear was a bit inconsistent if I remember right. I don't quite understand why yet.

I've not spliced the front negative outputs to the rear negatives, mind you. She's fine as is so far. And since there were comments to just leave the negatives unplugged, so far I can't figure that might be a problem. All the more since the BMW speakers (stock I should say...) are grounded to the chasis.

I'll be taking her for a spin soon, so I'll know after some minutes drive if any problems arise.

[BMWDriver]

To sum it up, here's my wires setup:

From HU to BMW wires:
+Right Rear to +Right Rear
-Right Rear to -Right Rear
+Left Rear to +Left Rear
-Left Rear to -Left Rear

+Rigth Front to +Right Front
-Rigth Front capped (BMW wire capped also of course) These are now connected. See my reply below.
+Left Front to +Left Front
-Left Front capped (BMW wire same). Also now connected. See below.

+Battery to +Battery
-Ground wire to -Ground wire (not to the frame)
Ignition to Ignition
Illumination to Illumination
Remote to Remote
Pwr antenna capped (so far... or would I get reception if I spliced to remote?).
Antenna ... well do I need an adaptor or do I splice ?
Interruption : No cell phone, so no need -> capped.

[BMWDriver]

Now I get it. I had the negative wires mismatched because of the color schemes of the wires. Or worse yet, two positives on the same speaker. What I have are identical colored wires for the negatives of the left side speakers, and same with the right ones.

When I started replugging the negatives of the rear speakers, I noticed the wires were twisted together as to pair them up per speaker. So I had not taken notice of that.

The sound is very slightly inconsistent right now, and I will correctly plug the negatives of the capped wires. However, the problem is not serious right now and it turns out to have been a major improvement. I hear some very faint cracks once in awhile when the volume is high.

Man, this felt like re-inventing the frikkin' wheel. I was so thrilled when the speakers spat super sound ! Compared to what I had to endure with the old radio (it had an inconsistent output on rear right; plus the tape doesn't play)...

[BMWDriver]

That's done. But I'm still left with some noises when the engine runs - a bit of cracking. Plus I notice the volume goes down a bit. But that might just be the car sucking on the power.

Some grounding issue makes it cackle ?

(BTW thank you Anton for the hints.)

[liquidtiger720]

wait, so when I go to install my HU...with a harness adapter, I'm not suppose to hook up all the connections?


edit: help me! im really confused. Am I suppose to be using this pac-oem 2 thing? or am I okay just splicing hte wiring harness as ^^^ just did.

[BMWDriver]

wait, so when I go to install my HU...with a harness adapter, I'm not suppose to hook up all the connections?


edit: help me! im really confused. Am I suppose to be using this pac-oem 2 thing? or am I okay just splicing hte wiring harness as ^^^ just did.

What is your result so far ? I get a bit of cracking noise at high volume having all wires connected. I think Anton was suggesting to ground the negative wires of the speakers instead of connecting them to the negative wires of the new head unit. I, too, am confused, but I think we'll sort it all out.

So I will probably try grounding the negative wires coming from the speakers and cap the HU negatives. Or would that be unwise ?

[liquidtiger720]

What is your result so far ? I get a bit of cracking noise at high volume having all wires connected. I think Anton was suggesting to ground the negative wires of the speakers instead of connecting them to the negative wires of the new head unit. I, too, am confused, but I think we'll sort it all out.

So I will probably try grounding the negative wires coming from the speakers and cap the HU negatives. Or would that be unwise ?


I havent installed it yet. I returned my HU today,and am waiting for my new one.

[BMWDriver]

When you do get it, try at first with only connecting the positive speaker wires. Turn it on and see what happens. Then turn on the engine and see what happens. Then play with the fade and balance if not much comes out - go full back, front, right, left, front left... try everything.

If all fails, try connecting the negative wires which in my case results in cracking noises from the speakers at high levels of volume, or when sound rich music is played, but strangely, only when the engine runs. I'm not saying this will happen to you.

In my current case with all negatives connected together, jazz at normal volume (level 13 of 35 max) plays ok, with the occasionnal cracking noise when the music gets more intense. When I play techno, I often get that cracking noise, so I lower volume a bit. I gather that's electrons firing back to the speakers because of the voltage from negative wires of a modern HU...

From what I gather, the BMW configuration needs the negative wires of the HU to be at 0 volts. Modern HU negative wires have voltage to protect the electronics of the HU. So in order to avoid damage to the HU's sophisticated electronics, they now put voltage to the negatives, which is not BMW's config (in our beloved E34 as far as I can tell). So, the electrons going through the speakers have a hard time going back to the HU because they meet some resistance from that voltage. Thus the electrons fire back to the amp and cause those cracking noises when the energy level is high. The amp can't quite handle it. This is only my loose interpretation.

Friday or Saturday, I will try again without any negatives connected and see the difference with the engine on and off. Then maybe I can try grounding one or two negatives to the frame. If that still does not work, then eventually I will probably get an amp and speakers. But no rush though because I still get fairly good volume for my taste.

I got some answers from Anton. Thanks again Anton !

[632 Regal]

im just gonna stick in a huge MFin amp and pop a box in the trunk and call it a day, this sounds too confusing for a HU thats stock and works good...dont even need an EQ if I tap the rear bass speakers...as I guess.

Your work impresses me so far, sounds so much more complicated on our cars than it should be.

[jippijak]

i dunno i have an awia headunit with everything plugged in and the bal and fade all work perfectly. its been a year since i installed it. and its fine

[liquidtiger720]

Dang. Having lots of trouble getting the HU to work properly. So far, all connections made, huge amount of noise coming through when engine running. But, the noise disappates when the wires get moved...did I do some wiring wrong? Whats the correct way to crimp...connect the wires from the adapter to the hu harness?