Preventing the whine?

[Turbolader]

Hey guys, I'm getting ready to do the install on my system, and I've been reading a lot about whine. I think one of the first things you can do is run a common ground to the factory head unit from the same ground point as the amp in the rear.

So my question is what gauge wire should I run from the rear to the head unit up front? I know the factory head unit doesn't pull much power, but I am guessing the run will be about 15 feet. Will 14-awg work okay? I haven't seen the stock wiring yet, but I'm guessing it's even smaller than that.

Would it be worthwhile to wrap the bundle (of the high inputs going to the amp) in a conductor (Such as aluminum foil) to prevent any RFI, or will the high-inputs be high enough that any RFI would be negligible by the time the amp sees the signal?

I want to do the install right, and only do it once, so I want to deal with "possible noise" beforehand

Thanks!

[MrGraphics]

I have 0% whine from my factory head unit and I ran no extra ground wires to it.

The trick to not introducing whine is to do smart wiring of your amp. Don't cross power or ground wires across the speaker lines - keep the isolated. Keep the amp ground as short as possible. Sand the paint off the point where you ground the amp to the chassis.

If you do it right, you don't need anything special. If you have whine, you were sloppy.

My amp is in the stock location, and I simply removed the old amp and tapped into the wiring harness. I ran a 6 gauge power wire from the battery (added a fuse to that line), and used the 12V signal line from the harness to trigger the amp on.

Car Audio 101.

[VP Electricity]

Sigh... it's always easy at the keyboard.

By the way, you don't have to worry about RFI, but EMI is another story.

Crossing power and ground wires over speaker wires has nothing to do with RPM-related noise, I'm afraid. Even RCAs won't induce noise when the wire is perpindicular. It's parallel paths where induction can take place, and some argue it's theoretically impossible even then (I'm not one of those).

Rather than keeping every ground as short as possible, in BMWs, we always ground to the battery ground terminal (when the battery is in the trunk).

We integrate with the factory head unit all the time. We hate whine and don't allow it. However, the 1-series is more susceptible to whine than other BMWs, since the battery is smaller and the alternator seems to be noisier.

There are a few ways for whine to be introduced into the system. It can be inducted onto a PCB, it can be from a ground loop, or it can be from poor input gain adjustment where you're hearing the noise floor (usually if you are trying to get more from a smaller amp than you should be).

The gear selected has some part of it, and how you decide to integrate with the OEM HU is another (which system does your 2010 have? Base Stereo? Logic 7?)

You can also get RPM-related whine from your passive crossovers picking up inducted noise. When there is a second-order or higher crossover filter (most good speaker sets), there is a parallel inductor coil. That coil can act as an antenna and pick up noise out of the air (or from a grounding bracket, power wire, or the big metal plate under the red plastic cover over your (+) battery terminal).

[Turbolader]

Originally Posted by VP Electricity

Sigh... it's always easy at the keyboard.

By the way, you don't have to worry about RFI, but EMI is another story.

Gotcha, thanks!

Originally Posted by VP Electricity

Crossing power and ground wires over speaker wires has nothing to do with RPM-related noise, I'm afraid. Even RCAs won't induce noise when the wire is perpindicular. It's parallel paths where induction can take place, and some argue it's theoretically impossible even then (I'm not one of those).

Rather than keeping every ground as short as possible, in BMWs, we always ground to the battery ground terminal (when the battery is in the trunk).

We integrate with the factory head unit all the time. We hate whine and don't allow it. However, the 1-series is more susceptible to whine than other BMWs, since the battery is smaller and the alternator seems to be noisier.

There are a few ways for whine to be introduced into the system. It can be inducted onto a PCB, it can be from a ground loop, or it can be from poor input gain adjustment where you're hearing the noise floor (usually if you are trying to get more from a smaller amp than you should be).

The gear selected has some part of it, and how you decide to integrate with the OEM HU is another (which system does your 2010 have? Base Stereo? Logic 7?)

I have the really bad tweeterless base stereo.

Originally Posted by VP Electricity

You can also get RPM-related whine from your passive crossovers picking up inducted noise. When there is a second-order or higher crossover filter (most good speaker sets), there is a parallel inductor coil. That coil can act as an antenna and pick up noise out of the air (or from a grounding bracket, power wire, or the big metal plate under the red plastic cover over your (+) battery terminal).

This got me thinking. Would wrapping the crossover boxes in aluminum foil help reduce the possibility of inducted noise? I haven't looked at the battery setup yet, but is the big metal plate even needed? I don't mind yanking useless weight from a car

I'm using a Technic harness to run the signal to the trunk where I will have a blaupunkt tha555pnp amp. I plan to run separate lines to the underseat speakers to the sub channel on the amp. The fronts are going to be DLS PS4 speakers. I don't have a plan for the rear speakers, I'm honestly thinking about disconnecting them all together because I've never been at a concert where the concert played behind me.

I was thinking about running the ground wire alongside the technic harness and into the factory headunit (Carrying the ground from the same source as the amp -- I'll use the negative battery terminal for that, thanks for the suggestion).