mercedesBenzer

I read bunch of threads to find out what I needed to replace the stock radio with after market. I want to keep the BOSE setup and the amplifier. I bought a Pioneer unit and PAC SOEM-4 (LOC) and the harness to plug into the stock plug. I used the attached pinout to hook up the radio and the PAC output. I'm using the two pre-amp RCA outputs from the radio, it's hooked up to the PAC input and the output goes to the amplifier. I don't get any sound through the speakers. Is there a amplifier trigger wire that I'm missing, the only one I can't identify is the blue / brown wire that is normally clipped in the back of the Becker unit, is that the one ? or is there even a trigger wire for the amp ? Any other things I might be missing ?

Thanks,

oldsinner111

what I've heard is when you replace radio you need to replace amp.Cause factory amp not compatable with newer radios

mercedesBenzer

From what I understand the Bose system is pretty much a closed off system. Using odd speakers, watts, ohm etc. as such if you want to use diff amplifier you would have to replace the speakers as well. The way to beat that is to give the stock amplifier the input that mimics the Becker output. In oder to do that the pre-amp outputs on the new head unit is used and the PAC SOEM-4 (LOC) is hooked up to get the signal to the 4V input that the stock BOSE amplifier is expecting and everything should work fine. Does anybody know if the Bose amplifier works best with certain Hz input ?

ddz

I hate to say it but that first reply above you got was total crap. I have had great luck ordering from crutchfield with several mercedes, all but one has a bose system that I connected to. My current one on my s320, which I also plugged in to my e320 successfully (both with Bose amps), runs off a harness I bought with it from crutchfield that uses rca plugs to connect to the factory harness. You might be able to call them, even if you didn't buy the head unit from them, and ask about a wiring harness for your conversion. The only additional wire I had to work with was designated as amp turnon from the head unit, but I needed it on my s320 to raise the antenna. I do not have a separate amp turnon wire hooked up. Good luck....

mercedesBenzer

Thanks, ddz

Problem solved, sort of !!

Yes, I do have the snap in harness. Last night I activated pin 5 - Ant trig (12V when radio on) - Although my antenna is in the window and there is no antenna to raise. I had it hooked up with the SOEM-4 amp trigger wire. That did not work, then I used the trigger wire directly from the radio. That did it, next time I turned the unit on the speakers came alive and I get good sound, it's noticeably richer / fuller than from the Becker unit. I can choose output from 50Hz - 125Hz on the unit, it seems 100 - 125Hz sounds the best.

There is still one problem though, even on full volume at the head unit and the SOEM-4 turned all the way clockwise for each channel I'm not getting as much volume as I would expect, maybe about 60-70%. Any thoughts on that ?

mercedesBenzer

I think the RCA pre-amp doesn't put out enough voltage, the SOEM instructions claim the RCA pre-amp should be at 4v, mine is somewhere around 2V. I switched to the normal output from the unit and I can get all the volume that I want out of the speakers. Nice to have CD, Aux, iPhone and Bluetooth input ( hands free phone calls on the speaker system ) for just over $100 with better sound than the old Becker.

Alex.Johnson

If I would not have read this thread, I would not have found out how easy it was to replace my 1995 s320 stereo. I called Cruchfield. They sent me a new Alpine (usb port and blue tooth), with wiring harness, universal keys and an antenna adapter .. all for $126 (free shipping).
Every shop in town said the system would have to be rewired to make all 8 speakers play and they wanted $300 to do it. What a joke!
Next time you need help, call Cruchfield - money back guarantee and tech support if you are having trouble with installation.

THANKS BBZ!