Radio help

[mr_joshua]

My new to me Z3 has an aftermarket Kenwood unit. Looks fairly well installed. I did just upgrade the footwell and rear speakers to some Rockford Fosgate. They all fit perfectly. The car has what I assume was the HK system (at least the door tweeters and rear 4" were labeled HK).

My question/concern is I cannot for the life of me figure out if the speakers are all directly powered by the head unit OR are there hidden BMW amps in the trunk.

What will worry me is a lot of the factory stuff was either 2 or 3 ohm. The new speakers are all 4 ohm. I can re-trace wires and look a diagrams easily, but more often than not a 'buddy' on a forum like this has been there/done that. Do I need to remove the factory amp from the system? Do I have one?

Also, the rear 'sub' in the center seems factory too, but has a JL audio speaker in it. Is that factory? Where does the signal from the head unit come from? I don't see a specific 'sub output' from the head unit.

Thanks to ALL for your help so far. I've done a LOT to this car using these killer pages!

 

[ExMX5owner]

Cant help you with your specific audio setup, but what I can say is 4 Ohms is fine, generally a bit higher impedance is ok , lower can cause issues for the amp, here is an impedance curve for an 8 Ohm speaker, as you can see it spends very little time in the 8 Ohm region anyway , and I doubt very much if you will be able to hear the slight difference it would make to crossover frequencies between drivers..

 

[mr_joshua]

Cant help you with your specific audio setup, but what I can say is 4 Ohms is fine, generally a bit higher impedance is ok , lower can cause issues for the amp, here is an impedance curve for an 8 Ohm speaker, as you can see it spends very little time in the 8 Ohm region anyway , and I doubt very much if you will be able to hear the slight difference it would make to crossover frequencies between drivers..
View attachment 330353

Thanks for the reminder, yeah the speakers will be fine. What confuses me is I swear reading that some Z3's have two amplifiers in the boot, one for the sub and one for the other speakers. If the head unit can output 4ch x 35w....seems like that 'power' is useless since the speaker outputs from the head unit just go into another amp anyways. I guess I'll need to pop up the carpet trim in the trunk to figure out what I've got.

 

[ExMX5owner]

Thanks for the reminder, yeah the speakers will be fine. What confuses me is I swear reading that some Z3's have two amplifiers in the boot, one for the sub and one for the other speakers. If the head unit can output 4ch x 35w....seems like that 'power' is useless since the speaker outputs from the head unit just go into another amp anyways. I guess I'll need to pop up the carpet trim in the trunk to figure out what I've got.

I do believe that several variant of the stereo in a Z3, unfortunately I,m only familiar with the one thats in mine, It has no external amps, just some very rudimentary crossovers built in to the circuitry .. for example the rear center woofer is bi wired dual coil, ie: two voice coils sampling of the rear right and left, thru a simple inductor.. Its not the way I would do it..but there you go BMW at least did my one that way...