Slight alternator noise with ICE>Link

[el_duderino]

Glad to hear you like! I was amazed by these little things. We use them in most of our BMW OEM HU interfaces. Specs say flat to 0.5 Hz! (20 Hz with 7V of signal).

I'm pretty sure you could put one of these next to a piece of Romex inside a wall and be OK...

[btrvalik]

I spent the afternoon modifying the ice>link cable to include 4 RCA connectors. I plugged the iso-max into the connectors and went for a test ride. Much to my surprise, the iso-max made it worse and it also introduced some clicking sounds. After my experience with this device in my home system I was expecting it to do the trick. I'm wondering if one side of the iso-max need to be grounded?

Ken, any ideas?

[el_duderino]

What a pisser.

I heard those clicking sounds when I tried a Soundgate AUXBMW in an X5, and I think when I tried an LC6 (although I didn't try a lot with the LC6 to get rid of it).

I would try making a set of shorting plugs and inserting them into the input of the GLI and leaving the output connected and see if you still have the noise. If you do, those transformers are picking it up out of the air. Maybe you can relocate it?

If you don't, then I would try using just the (+) and try that (as a guess...)

Lemme think on this one... it sounds like something in your car is a bad actor relative to other X5s...

[silkster]

Hey Ken as you know my car is about to go under the knife again for a number of things, and the situation requires as much coaching up as possible..

Now as for the IsomaX I plan on tapping into the rear channels outputs from the tuner in the trunk so that i would be able to use the fader ..would i then need 2 isomax or will 1 do the trick for both front and rear channels..

Also when you tapped into the rear channel in the X5 for the ability to fade did you also use your homebrew method of "hacking the male end of the rca and wiring the female end" to the wires in the tuner ..

[btrvalik]

So today I tried the following:

1) short out the inputs on the iso max then plugged into the cd changer input
- About the same (but not worse) buzz as an open cd changer plug
2) share the ground across the input and output of ISO max
- same as 1
3) short out cd changer input
less noise but still some popping noise
4 Connect the ipod headphone jack to the CD input (with and without) iso-max
Same amount if noise as using the standard cable

I'm wondering if I'm looking at this improperly.. maybe I need some powerline filtering / grounding? I've also notice that the bi-X headlights will contribute a buzz.

Argh.. all I want is that my Ipod has the same fidelity as the CD player playing Mp3s. I like the control of the ICE>Link but this noise issue is really getting me mad!

[el_duderino]

Are you talking about filtering the Icelink power?

Maybe... there is a grounding bracket forward of the changer on the fender that broadcasts tons of EMI too...

What if you get all this stuff as far out of the compartment as possible and lay it on the load floor? Any change?

[btrvalik]

If the changer audio input is open or terminated with the iso-max I get popping and buzzing from the bi-X headlights but no alternator whine. If I terminate the changer input with the ice>link I get alternator whine but no popping or headlight hiss. Moving the ice>link cable does not change anything. From this I conclude the following:

1) The radio to changer link is picking up the popping noise and hiss. I believe this is due to the fact the the far-end is not grounded is the point where the cable shielding is grounded, anything that floats the ground causes a problem. Now that I type this I'm not sure if I tried just grounding the changer side of the iso-max.
2) The alternator noise is coming in on the ice>link power and ground. May only be when it is connected to the changer input.

I was thinking that possibly filtering the ICE>link DC may help. Is the power clean or noisy in the X5? I don't have access to a scope these days. I have not had to use a choke on a car audio project in a long time. Is it just that the ICE>link does little or no filtering and most audio equipment does these days? I'm still hoping that the noise is ground loop related since the path from the radio to the rear to the ice>link is so long.

I think my next step is to try a radio-end kit to shorten the total run length. It will need a little re-wire since I have bluetooth, but it is the only thing I can think of at this point.


At this point I think I'm going to try the radio end kit.

[btrvalik]

Using a radio-end ice>link kit solved this problem. If you think about it, running the aux input from the MID to the back, then up to the console is really just creating a giant antenna. When it comes to audio cables, short is almost always better. The noise I was picking up might have been from my sub amp since it is an Alpine class D amp mounted in the rear corner near the CD change connector. I did not verify this, but it could be a source of noise.



Bruce

[el_duderino]

OK, good to know - if noise persists, radio end kit, but pull fuse on any Class D amps nearby first.

Congrats on beating this thing!
Usually the twisted pair audio lines in a BMW are resistant to acting as an antenna... I suspect that the amp might have been being picked up by PCB traces.

But good work!

[btrvalik]

I did not verify the Class D theory...only thought of it after the radio-end install. After further driving I still can hear some noise on very quiet passages with music like classical guitar but it is a lot less than before. I think that this is also load dependent. Seems to happen more often with headlights are on. The real problem is...these BMWs are just too quiet! In my other car I can't here any alternator noise.. it's drown out by the supercharger whistle and exhaust note