Need some guidance with aftermarket audio

[OneFastMac]

I bought a 2004 Z4 in October and according to BMW, it was originally equipped with the "Premium Hi-Fi" audio system. It does not have navigation and the woofers behind the seats have been replaced with aftermarket speakers. I can't remember what brand, I'd never heard of it but they're orange, lol.

ANYWAY, it also has an Alpine UTE-73BT radio and a CRUNCH 1100watt 4 channel amp "installed"
I say "installed" because only the right channel audio plays, but it plays through all ten speakers.

The wiring is a mess of black electrical tape and I haven't had the courage to get down to the nitty-gritty and see what the issue is.

I've found on this forum plenty of technical specifications for the wiring, but what I have yet to find is a step-by-step instruction for how to wire in aftermarket audio. I see a lot of posts where people ask for help, but usually involves OEM equipment OR I see posts where people have solved their issues by paying someone else to do it.

My big question is, am I boned? Is there a way for me to use what I already have to power all ten speakers properly?

The audio system is my big first-of-the-year project for the car, followed by getting the top working again.

If someone can point me in the direction of aftermarket audio installation instructions, or if you can provide the guidance I need I would really really appreciate it.

[Clearancediver]

Boned…..

Your original unit couldn’t be replaced by aftermarket radio/amp….which is why it was stripped out completely and a aftermarket radio…amp…speakers “supposedly” installed.

[OneFastMac]

OK
So last night I really dove in to the mess of wiring. I think I understand better where I'm at and how to move forward. At the very least, I've got a temporary fix where I actually have stereo sound playing.

The previous genius that wired everything up had channels 1 & 2 both wired in to channel 2 signal.
Channels 3 & 4 were both wired in to Channel 1
The speaker outs were only wired up as channel 1 and 2 with channels 3 & 4 bridged for the subwoofers... I assume.
The speaker out wires were connected in a way that Channel 1 went to all 5 left speakers and channel 2 went to all 5 right speakers. This is why only channel 2 audio was playing through all 10 speakers.

I rewired channels 1 & 2 to the appropriate inputs so now left and right channels play through left and right speakers. There's still a lot of mess to clean up and because BMW used the same colored speaker wires for different speakers, there is some testing I will have to do.

Going forward I think I will have to replace the cheap-o amplifier as it simply does not have the features needed to power all ten speakers appropriately. I'm going to cut my losses and go for the JBL DSP4086 8 channel amp to give myself more ability to fine-tune the sound to each speaker.

My new question is: Do each set of speakers have their own crossover built in? Or did was the oem HIFI amp a DSP amp and that's why this seems so much more complicated?

[Clearancediver]

You had a DSP amp with the high end 10 speaker system..(Carver System). That is why the amp was removed and the speakers replaced etc.

It’s the same system I have … along with the same year Z4. You can’t replace the OEM head unit with an off the shelf radio. The DSP amp required a signal from the head unit… which is why the amp was replaced… and of course the speakers as the BMW speakers are 4 ohm speakers if I remember correctly and not compatible with the amp etc.

This is why the “gut” job you encountered…..that along with the amp being priced at $1K bought new…

There are many threads/posts on this specific issue.

[OneFastMac]

Thanks for the confirmation!!
Well, maybe that’s what I wasn’t quite certain of and what was probably holding up my thought process. I didn’t have any solid info about what exactly the oem equipment was and while I’ve seen many threads about aftermarket radio installs, it was usually from people who already knew what they were dealing with. This is my first BMW and first time messing with a “high end” system.

Like I said, I think I have a pretty solid game plan to get the audio system back up to snuff.

But man… if I ever meet the five year old that wired up this current system I will very sternly place them in time-out! It’s an absolute mess.

I think I can get some decent sound if I wire the rear channels up with the current amp’s low pass filter. That might hold me over until I can get that JBL amp.

[OneFastMac]

It took me all day and a lot of referencing old posts for speaker wire colors, but I managed to get some decent sound from this cheap setup!

Since I’ve only got FR & FL channels, I split them at the amp and put a low pass filter on speaker channels 3 & 4, and wired those up to the kick panels and subwoofers.
Channels 1 & 2 are wired up to the tweeters, doors, and rear mid speakers.

It’s not stellar, but the signal is clean and I couldn’t hear any distortion at higher volumes.

I’m going to (eventually) update this thread with an easy to read speaker wiring diagram for the next fool that buys a trashed DSP Z4 lol some of the reference sheets being shared around are not very easy to read and even worse if you decide to print them.

[OneFastMac]

https://www.zpost.com/forums/showthr...8#post29772848

I made a new post with all of the info I learned from doing this on my own.