[ctuna]

The radios have a history of doing this.
You could try injecting a clean signal from another
source at the amp to see if its from the radio or idrive.

[jfaghihnassiri]

I know this is an old thread but I think I can share some helpful info - I had this same problem with a similar setup (2011 328i / e90 + technic harness + JL XD600/6) and after banging my head on the wall for weeks here's what fixed it for me -

I took out my head unit (lots of videos on youtube) and wiggled the two big cables that plug into the back right of it. I assume one is antenna and the other is power or ground. With my wiggling I could hear the noise come and go, so I wrapped them in some electrical tape and put the head unit back with the cables in a position/tightness that did not cause noise. So far so good!

It's important to note that you should first diagnose if your problem is coming from before or after the RCA<->AMP connection by unplugging the RCAs and listening, and also plugging in a different source and listening. Hope this helps!

[sfarisminhas]

I have something similar. It's not an alternator or engine whine. It's present when I start the engine, not with the ignition. I get the hiss and some static when I start the engine which goes away and doesn't return until I put my foot on the brake. The volume doesn't increase nor decrease, it stays constant and only present at very low volume and only when braking, which makes me think something is getting induced into the wiring. I have an aftermarket 80prs with an active front stage comprising of tweeters, mids and the underseats. I changed the RCA's and the problem went away for a while. My amp is a JBL 7535 5 channel amp. The only thing I can think that has changed is that on the sub channel when setting the gain using the SMD DD1 I put in -10db of gain overlap instead of the -5db that I normally put in which puts an increase in the potentiometer on that channel. I also have an oscope to check how much voltage is being shown at the speaker output to see if it is putting out the recommended 4x75 watts at four ohms and the 300x1 at 2 ohms. It's such a chore taking the boot lining etc out all the time. My amp is installed on the left hand side where the factory amp normally is and is grounded to the bolt on the left fender.

[OnlyDriveGerman]

If you're talking about aftermarket stereo parts and hissing, you're almost always going to find a problem with the ground wire. Possibly but more unlikely, your getting static's from wires being to close to each other. Try to keep the wires separate but I'd start with your ground wire.

[sfarisminhas]

Originally Posted by OnlyDriveGerman

If you're talking about aftermarket stereo parts and hissing, you're almost always going to find a problem with the ground wire. Possibly but more unlikely, your getting static's from wires being to close to each other. Try to keep the wires separate but I'd start with your ground wire.

I had originally ran all the wiring along the left hand side and tied both the speaker and RCA's with the factory loom up the fender and into the cavity where the factory amp location is, which is where I have my aftermarket amp. The static was coming through when I pressed the brake. I disconnected the plug and discovered that the noise had gone, there was my light bulb moment. I have since rerouted the RCA's and not run them under the glove box as I had done, instead I have run them down the centre console into the hole in the carpet along the seat and through the hole into the boot area. I have also dropped the speaker wire down so that nothing runs with the factory loom. Running the RCA's down the centre console wasn't easy let me tell you. Tomorrow I'll tidy up the cabling.

[sfarisminhas]

So yeah. I've managed to confirm it, every time the RCA's go anywhere near the factory cabling on the left passenger side where the cabling to the brake light also is, it's picks up a noise when I press the brake. I have confirmed this with 4 sets of RCA's. Initially, I thought it was my stinger RCA's but fortunately it wasn't. When disconnecting the molex plug for the lights, the noise disappears with it. So now the question is, anyone else experienced this or even why there would be a buzzing when pressing the brake, which could be a problem in and of itself?

[soulgod123]

i had all sorts of whining, when its raining or wet outside, on my DSP volume is like at 50% if its higher than that i can hear speakers just by sitting at the drivers seat, had to ground RCA's at the back of the head unit(aftermarket pioneer, probably pico fuse) by using copper wire and couple bolts - this saved my life , and last thing i did used splitter on my 4 channel amp
so the setup at the end is like:
from HU fronts and rears to DSP than from DSP front goes to 4 channel amp with splitter, rears to underseats, and from head unit third pair of RCA's straight to sub amp so i have controls for my sub on my HU
so i had 3 problems at once once i finished my build it took me months to sort out the buzzing
https://www.e90post.com/forums/showt...php?p=21637412
post #262 for reference

[sfarisminhas]

Originally Posted by soulgod123

i had all sorts of whining, when its raining or wet outside, on my DSP volume is like at 50% if its higher than that i can hear speakers just by sitting at the drivers seat, had to ground RCA's at the back of the head unit(aftermarket pioneer, probably pico fuse) by using copper wire and couple bolts - this saved my life , and last thing i did used splitter on my 4 channel amp
so the setup at the end is like:
from HU fronts and rears to DSP than from DSP front goes to 4 channel amp with splitter, rears to underseats, and from head unit third pair of RCA's straight to sub amp so i have controls for my sub on my HU
so i had 3 problems at once once i finished my build it took me months to sort out the buzzing
https://www.e90post.com/forums/showt...php?p=21637412
post #262 for reference

How are you finding the front focals? What power is being sent to the drivers? I have a JBL GTR 7535 amp. It does 75 watts x 4 and 350 watts on the mono channel. Small and compact fits in the left hand corner where the original amp would normally sit. I might swap the amp and get an Alpine PDX V9 which will give out 100 watts x 4 and 500 x 1 because I feel the underseats aren't getting enough power.