Constant hissing noises from my new sony head unit :( - Page 2 - PeachParts Mercedes-Benz Forum

wir10 · #16 10-25-2006, 07:22 PM

Quote:

Originally Posted by nazrat

I have a strong suspicion that you have an amp in the trunk. We had exactly the same issue with our C280. The hiss was due to the mismatch from the new radio and the amp. You can apparently buy a couple of line level converter modules, and adjust this and that, but here is what I did:

http://www.luddite.net/c280/radio.htm

First thing to do is look for the amp, or at least for the fuse in the fuse box for it. A good sign to me that you have an amp is that you got *no* sound without the blue (remote) wire connected.

-Tad

I apologize for resurrecting this thread, but I had a question -- where does the Stock Amp fit in this picture? Am I correct to assume that you are bypassing the Stock Amp and using the internal Amp of the Aftermarket HU?

Maruzo · #17 10-25-2006, 07:50 PM

You can't bypass the stock amp without rerouting the speaker wires. If you want to avoid double amplification, you can do one of two things:

1. get an adjustable line level output converter (i used a PAC OEM-2 model from ebay). connect it between your aftermarket hu and the factory harness. This converter can reduce the amplification of the aftermarket hu to nearly zero, thus reducing majority of the noise. Of course, you would be using the factory amp to power ur speakers.

2. to bypass the factory amp, you can read up on this guy's work: http://www.luddite.net/c280/radio.htm. He is quite handy with electrical stuff and hardwired his aftermarket hu to the oem speaker leads via the use of some capacitors/ resistors.

Good luck!

nazrat · #18 10-25-2006, 08:40 PM

That guy is me. It just uses some resistors to make the new head unit think that it just has normal speakers. The Bose speakers have such low resistance that they appear (electrically) like almost a dead short, which is very bad for an amplifier that isn't designed for it.

The easiest route (although not cheapest) is to remove the speakers and replace them. You can re-use the tweeters, install new speakers in the front doors and rear deck and have a decent sounding stereo. Add rear door speakers and a subwoofer (in the trunk) for fuller sound.

-Tad

Maruzo · #19 11-01-2006, 03:46 PM

Hi Tad:

Nice seeing you here again. If you decide to change out the factory speakers, would you still need to bypass the factory amp? If so, how can that be done?

nazrat · #20 11-01-2006, 05:22 PM

Well, I never left but I tend to be on the diesel forum more often.

You'd still need to bypass the factory amp, but you wouldn't need the resistors. In all honesty if I was replacing the speakers I'd be tempted to run new wires. The 4 dash speakers are easy, the front door speakers shouldn't be too hard and the rear deck speakers are easy. The rear door speakers will probably be the hardest.

-Tad