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      01-24-2013, 05:54 PM   #13
Technic
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Drives: 2015 320i
Join Date: Apr 2005
Location: Ft Lauderdale, Florida

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2004 M3  [0.00]
You swapped a 180W max OEM amp with a 600W aftermarket amp. Original OEM hiss will increase proportionally.

A DSP processor could solve this problem by digitizing the OEM signal and thus removing the OEM noise/hiss floor before the aftermarket amp, everything else being equal.

Quote:
Originally Posted by MJ777LR View Post
Thanks for the link! I read through some of the posts and it seems my symptoms are pretty similar. I've attached a photo of my amp mounting and wiring.

The amp/crossover unit is mounted on two custom milled aluminum panels. The lower panel is where the Jehnert crossovers are mounted, and the upper panel is where the XD600/6 is mounted. The upper panel has access holes to plug cables into the crossovers below. The entire assembly is mounted onto the OEM amp bracket (which had its two angled metal arms on the inboard side cut off). The custom milled panels have access holes on them to allow securing the OEM bracket to the factory mounting points. The two decks are separated using nylon spacers, and between the spacers and panels, rubber washers are used to provide shock/vibration dampening.

My symptoms are basically:
- Hiss/static from midrange/tweeter on both left and right doors
- Hiss is proportional to gain setting
- Disappears when I unplug RCA inputs from the amp
- Hiss was there when OEM amp/speakers were being used, but just much less noticeable (actually a lot less!)

In the photo, you can see where the RCAs from Technic's harness is connected to the male-male RCA extensions. The red live wire is temporarily crossing over the trunk to the battery, as I haven't yet finalized its routing. Any clues perhaps?

One other thing... I noticed earlier the amp itself was making some sort of electrical humming noise. When I wiggled the power and ground cables near to where they insert into the amp, the humming stopped. Anyone know what this is about?

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-2015 F30 320i, Imperial/Oyster, 8AT: August 2014 ED
-2012 E92 M3 Jerez Black/Rust Brown, M-DCT: Gone
-2008 E90 M3 Melbourne Red/Bamboo, 6MT: Gone
-2007 MK5 GTI United Grey/Grey, DSG: Gone
-2004 E46 M3 Carbon Black/Cinnamon, 6MT: Gone