Speaker Noise

[lkv0315]

Originally Posted by wpoll

There is something fruity going on there - until you can get the head unit to operate with the aerial unplugged, you aren't going to track this down.

The head unit should be able to be powered up with just three wires connected - power, ACC power and a ground. You won't get sound but it should power up.

I think I’m going to start from the ground up and redo all the wiring for my head unit. With that being said, where is the best place to tap a power and acc power from the front of the vehicle?

[80stech]

Power/ground can definetly be a problem but don't forget about the interconnects. Basic rule of thumb is twisted pair AND shield to ground to the SOURCE.

[lkv0315]

Originally Posted by 80stech

Power/ground can definetly be a problem but don't forget about the interconnects. Basic rule of thumb is twisted pair AND shield to ground to the SOURCE.

Would you mind elaborating on this a bit? By interconnects do you mean the RCA cables? Mine are twisted pairs and they take a completely different route than my ground does.

[80stech]

Yes, twisted pair is good but they need to be shielded preferably foil and that shield should only be be connected to the signal source.

realizing that the shield is same as ground in RCA cables it still matters.

[wpoll]

FWIW, twisted pairs only really work well in balanced audio - not the un-balanced audio found in car audio systems.

The unshielded audio wires could well be a significant source of noise (especially in a car full of high current PWM signals!) but you still need to sort the grounds and power weirdness.

The best place to connect the power is where the OEM radio was connected - assuming it was in the dash (MID + Business/Professional CD etc.) - I don't know what your car had originally.

[lkv0315]

Originally Posted by wpoll

FWIW, twisted pairs only really work well in balanced audio - not the un-balanced audio found in car audio systems.

The unshielded audio wires could well be a significant source of noise (especially in a car full of high current PWM signals!) but you still need to sort the grounds and power weirdness.

The best place to connect the power is where the OEM radio was connected - assuming it was in the dash (MID + Business/Professional CD etc.) - I don't know what your car had originally.

Yes I had the business CD. As far as I know though I am pulling power and ground from the factory harness via an adapter

[lkv0315]

This evenings update:

Tracked it down to being an issue with my RCA cables crossing with the lighting signal. I never realized it but when I unhooked everything and stood behind the vehicle with the lights on, I could hear that exact same frequency from the tail lights as was coming through the speakers. So with that being said, I suppose I will try to run my RCA’s a different way or I might just wrap shielding around them the whole way (that might be costly though). Would this be the practical application for the ferrite cores I had mentioned earlier?


Sent from my iPhone using Xoutpost.com

[lkv0315]

Also, just to clarify, if my radio has an adapter harness that takes the important functions like power, constant, ground, lighting, etc from the factory harness, should I keep using that or should I switch to a body ground and get power from somewhere else. If I should get power from somewhere else, where would that be? As far as I’ve seen the only place where there is actually a power bus bar is in the trunk.


Sent from my iPhone using Xoutpost.com

[Bmwe5320023.0]

I'm chasing a similar problem with high pitch sound on a new sound system. Gets worse when turning headlights in.
Not sure is you fixed your issue?

[lkv0315]

Originally Posted by Bmwe5320023.0

I'm chasing a similar problem with high pitch sound on a new sound system. Gets worse when turning headlights in.
Not sure is you fixed your issue?

Yes, actually. It has to do with the PWM signal from the tail lights that preserves the bulb life. Do you own a BMW Scanner 1.4.0 tool/software? In side of the LCM settings you can change them until it’s a constant signal instead of a pulse and it will stop. Alternatively, you could alway just move the electronics away from the tail lights and the wires that drive them, like where the spare is supposed to go perhaps.