HELP! Motor Phase Interference Noise on EBike Stereo...

Hello. I'm running the veloamp ebike stereo amplifier from ebikes.ca - great sound, and I'm having a problem with the reception of motor phase hum on the MP3 input line. When I have my player connected, and playing, it works fine. However, if I shut the mp3 player off, I suddenly get fairly loud phase noise playing through my speakers, as though it were picking up interference from the controller. If I remove the jack to the player and hold the end of the jack in my finger it makes the noise even louder, as though my body were amplifying the signal too. So, when my player is out of juice, and I take it off the jack, my bike is suddenly a lot louder, with motor noise coming out of the speakers. How can I isolate the jack? If I pull the jack right out of the amp itself on the other end of the line at the amp, the noise doesn't happen. It is as though the input line in is acting as a kind of antenna when the player is not operating. It is still present but not so loud when I leave the line jacked into the player, with the player off. It doesn't seem to be picking it up "through the air", as I can run the whole system with no problem, on a different battery, but in the same physical position - no interference. So, the phase signal is somehow getting into the line physically? from the controller or something.

What do the electronics experts say?

You are hearing the equivalent of an earth loop - the buzz test is a pretty common way of checking an amp is on (with your finger on the input).

I think you are saying that if you run it off a different battery, then the noise is not there? Sounds like the power supply is coupling noise - try using one of those isolating transformers that you would use on a car stereo, this will probably fix your issue.

Thanks...yes, if I run the stereo on a different battery not connected to the controller, I don't get the buzz, while the wheel is running on the main battery. It is funny that it is just when I have the MP3 line in connected to the amp, with no live player that I get this phenomenon...The noise is proportional to the throttle when it is doing this...

I agree with "heathyoung" in that you probably have a ground loop problem.

Here's a link that may help you address this issue:

http://www.termpro.com/articles/noise.html

And here's a link to a product that might also help (Radio Shack may have a similar product).

http://www.crutchfield.com/S-dKTM5EjKvuv/p_127SNI135/PAC-SNI-1-3-5-Noise-Filter.html?tp=2653

Thanks guys...I really appreciate your help. Those links look like just the ticket. Cheers.

Try a ferrite bead of some sort. Pick up a few different types (they're cheap) and try them around the signal and power lines (more importantly power). This can help reduce some of the noise. It may not be a ground loop at all. Ebikes are notoriously noisey (electronically)

It turned out that I just needed a shielded cable...Good advice as always from ebikes.ca...anybody want to buy a ground loop transformer?

Try listening to a radio on an e-bike...

Somehow I don't think the chinese controllers go through EMC testing :wink: