Radio Distortion
Hey, I've had my e34 for about a week now after owning an e30 for 4 years, and I must say, "WOW". These are a nice series. Anyway, I took the Alpine CDA-7894 from my e30 and put it in my new e34 530i. I used the circuit city harness and hardwired it to the alpine harness (not using the negatives and not forgetting the blue wire). Everything is working, however, the sound is distorting very quickly as the volume knob goes up. Here are my theories, please pick one that you think is correct:
1. The bmw harness goes to an amp expecting 5 watts and putting out 20. The alpine deck puts out 60 watts per speaker because it has a "built-in" amplifier. This should be sufficient for the speakers, so I should just bypass the amplifier altogether.
2. The HU has 3 x 4V preamp outs (RCA). I should connect these to the + on the bmw harness, that way it will be sending a low power signal to the amp for amplification.
I am a newbie at this and need help. Any comment you have would be great. Thanks
Rory
4 Grand Master
Common problem but no serious solutions. Everyone tried all sorts of things but cannot find the right solution to this problem. It seems to me that this Alpine use common ground... which is different from floating ground that factory used...
Try this... hook up all the grounds for the speakers and see if it improves.
Big Time Poster
2. The HU has 3 x 4V preamp outs (RCA). I should connect these to the + on the bmw harness, that way it will be sending a low power signal to the amp for amplification.
if you are connecting a powered signal (your head unit amp) to an amp you will have problems. it is also possible to ruin amps this way as well depending on how strong a signal you are putting into the amp. run the hu directly to the speakers or disable(in your case bypass) the hu amp as you outlined above. i will post pics and diagrams of my setup along with some devices i have that clean up the cabling and improve sound when i get home. i have an alpine hu in my 530 as well.
Big Time Poster
http://shmuck.u37.neureal.com/BMW_HU_ALPINE/
HU RCA Outs_>RCA Input Adaptor_>Wiring Harness
the wiring harness wires directly into the rca adaptor box. it transforms the front and rear speaker leads to rca connectors. any car aduio specialty store will have this box, or be able to order it. if not you can buy two rca cables and cut them in half. then splice the speaker leads to the rca connectors. bottom line is you cannot run a amplified signal into another amp you will get distortion.
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