tapping power for sat radio

[lekmedm]

Hi all. I've been doing some searching, but I didn't find anything covering this issue.

 

I just installed the Leptronix aux in device which works great. I connected a Sportster 5 Sirius radio and I'm getting some ignition noise through the speakers. The radio's power is hard wired in using a kit, and I tapped power from the back of the power outlet under the radio in the console. The sat radio is on the left of the steering wheel and the power wire runs across and under the steering wheel in order to get to the outlet in the center. Should I look for a different power source, or is my wire running along something that's picking up the igition noise? When I play a CD, the sound is nice and clean.

[RedFloyd]

Are you hearing alternator whine or something else? You should not hear alternator whine since there is no ground loop when using the Leptronix aux in. Do you hear the same thing when you're using your ipod?

 

You may try to put a filter on your 12V power near the sat radio, maybe it will help. Or you could take your power from the hu harness.

[CzarDestructo]

The supplied satellite radio power adapter should be a high quality switching power supply and really shouldn't cause any noise nor need a filter. As RedFloyd recommended test the aux in with an iPod or something battery powered and see if there is still noise. The floating power supply (aka battery) will give you a nice clean signal to gauge if the problem is the Sportster or the aux kit. Another easy test would be to unhook anything from the aux input and crank your volume all the way up to see if there is a hum.

[lekmedm]

Well, my goal was to have the satellite radio hardwired in for a clean look.

 

I actually found a fuse tap at Autozone for the mini fuses we have in our Subies. I didn't know there was such a thing, so I'm now piggybacking on the "cigar" fuse. But actually, that didn't solve the problem. It seems that I get the noise when I have the iPod connected to its car charger. The noise also increases in frequency with acceleration. Now, as long as the iPod is not plugged in, it plays nice and clean and the satellite radio plays nice and clean.

 

So the question is, how can I keep the iPod charging in the car?

 

Thanks for your help.

[CzarDestructo]

So the satellite radio no longer makes noise only the iPod when it's in it's dock? Did you have the iPod charger plugged in before when you were doing the sat testing? What kind of iPod charger are you using, something from Apple or a generic one?

[RedFloyd]

For the benefit of all, I will respond to your pm here. So you want to use both the sat radio and the ipod together using a splitter on the aux in. You have two problems, the first one is noise from the sat radio and the second is that the sat radio is not working when the ipod is plugged into the splitter.

 

Okay, to help me understand, please clarify this:

- if the sat radio is used alone, plugged on 12V, does everthing works fine?

- if the ipod is used alone, with it's charger, does everything works fine?

- If the sat radio is plugged on 12V and the ipod runs on it's battery, do you hear noise and does everything works great?

- if both the sat radio and ipod are plugged on 12V, do you hear noise and does everything works great?

 

From what I understand, it seems like there is a ground loop between the sat radio and the ipod. I want to tell that the aux in module is not ground referenced, so no ground loop is possible with the aux in board (as long as it was correctly installed and that the board works fine (don't worry about that, I tested it myself before shipping)).

 

To avoid the ground loop, the simplest solution is to use the same 12V-gnd source for both the sat radio and ipod.

 

Another source of problem could be the low impedance of the ipod output stage wich make the sat radio impossible to drive it's own ouput when both are plugged into the splitter.

 

So, if using the same 12V-gnd source for both is not helping you, you will have to use an electronic mixer instead of the splitter. If I had the same problem as you, I would built myself such a mixer, so I don't know if something like that currently exist on the market. The kind of mixer you are looking for is an active one wich will mix both signals into one with high impedance input. Also, it's inputs must not be ground referenced, to avoid ground loop.

 

If you're familiar with electronic assembly, I can draw you a schematic that you could build by yourself on a perf board.

[lekmedm]

Thanks, Sebastien. I think perhaps this may help some others as well.

 

I think you misunderstood a bit from my PM, so I will clarify and answer your questions:

 

 

So you want to use both the sat radio and the ipod together using a splitter on the aux in. You have two problems, the first one is noise from the sat radio and the second is that the sat radio is not working when the ipod is plugged into the splitter.

 

First, noise is not heard only while the sat radio is playing. You can also hear it with the iPod playing, but only when the iPod is plugged into a car charger (in the armrest, btw). When the iPod is not charging, there is no noise. Second, the sat radio does work with the iPod plugged into the splitter. The sat radio does not work when there is no device plugged into the second input.

 

 

 

 

 

Okay, to help me understand, please clarify this:

- if the sat radio is used alone, plugged on 12V, does everthing works fine?

Yes, but only if another device (iPod, cell phone, etc) is plugged into the other input line.

 

- if the ipod is used alone, with it's charger, does everything works fine?

No, there is noise.

 

- If the sat radio is plugged on 12V and the ipod runs on it's battery, do you hear noise and does everything works great?

No noise. Everything works great.

 

- if both the sat radio and ipod are plugged on 12V, do you hear noise and does everything works great?

There is noise under these conditions. (Remember, the sat radio is now hardwired to the fusebox under the dash with a fuse tap.)

 

 

From what I understand, it seems like there is a ground loop between the sat radio and the ipod. I want to tell that the aux in module is not ground referenced, so no ground loop is possible with the aux in board (as long as it was correctly installed and that the board works fine (don't worry about that, I tested it myself before shipping)).

 

To avoid the ground loop, the simplest solution is to use the same 12V-gnd source for both the sat radio and ipod.

 

In my amateur's brain, this sounds plausible. The sat radio is currently grounded to a screw near the fuse box. Perhaps if I extended a line from the sat radio ground to the armrest socket where I plug in the iPod charger and use that ground, all this may go away...?

 

Thanks for all the help!

[CzarDestructo]

The iPod charger is causing the noise. Find one thats higher quality.

 

The power supplies that power today's devices in the car are switching power supplies. To explain it briefly, basically you get voltage in on one end and you want it to be a different voltage on the other end, whatever your device needs. A switching power supply switches the power on and off really fast a varying rate to achieve the desired voltage on the other end. Cheap ones will induce a noise, at the switching frequency, into your electrical system. This is the hum you hear.

 

Is this an Apple supplied charger or a Chinese deal from ebay?

[lekmedm]

The iPod charger is causing the noise. Find one thats higher quality.

 

The power supplies that power today's devices in the car are switching power supplies. To explain it briefly, basically you get voltage in on one end and you want it to be a different voltage on the other end, whatever your device needs. A switching power supply switches the power on and off really fast a varying rate to achieve the desired voltage on the other end. Cheap ones will induce a noise, at the switching frequency, into your electrical system. This is the hum you hear.

 

Is this an Apple supplied charger or a Chinese deal from ebay?

 

I have been using this from Best Buy:

 

Griffin Technology - AutoPilot Apple® iPod® Controller

 

http://www.bestbuy.com/site/olspage.jsp?skuId=8673205&type=product&id=1203815033701

[robby-subie]

Hi,

 

Although slightly different, I thought I would post here since I also have a humming problem. My 2009 OBW (with HK stereo) has an aux-in in the center armrest. It hums through the speakers when I turn the stereo to the aux input while not having the iPhone connected and having the headlights turned on. The sound disappears when I turn off the lights. The sound also disappears when I disconnect the cable to the aux-in (while the headlights stay on).

 

There is no humming when I have the stereo tuned to aux and do not have the iPhone connected (with the headlights turned off).

 

 

Any thoughts?

[jhig]

I installed the Lepronix last night. It works great with my Ipod but when I try with my satellite radio it doesn't work. If you pull out the aux jack out a little I get sound and it sounds horrible of course since it isn't connected all the way. Any ideas why it would do this??? I'm powering it with the supplied car charger.