Update: the decoupling capacitor makes it near silent with lsdj, but not if the link cable is plugged to a MIDI source from mgb or pushpin . This happens with at least two of my DMGs so think this might be a feature not a bug. Will probably be building another Arduinoboy and link cable soon anyway so will see if either helps...

Both of my USB arduinoboys do this (one is from you and the other is a Thursday Customs one). When I have the arduinoboy plugged in and audio going to my interface there's a constant low hum/buzz like you get from a noisy power supply.

EDIT - oh, just realised that wasn't at me. oops.

mine's an old XIWI one.

Which arduinoboy are you referring to? Is it one of mine? Haven't noticed this but admittedly I haven't really looked for it either.

thanks....

I've got capacitors in the post, so will let you know if that improves it.... although if you're powering the Arduinoboy from USB maybe it won't.

hmmm.

Just chiming in that I get this as well using my USB arduinoboy. I assumed it was some interference with my audio interface or something but I really don't know.

Just on the off chance anyone has experience of this...

My newly prosounded gameboy is pretty quiet... but when it's got the link cable from my arduinoboy plugged in it suddenly picks up what sounds like slowly pulsing electromagnetic interference.

I should probably check if linking it to another DMG causes the same issue and eliminate "something I did to the link port" from the equation... But my current theory is that between the backlight and the (link cable powered) arduinoboy it's drawing too much power.

So... if that's the case is it likely adding a decoupling capacitor to the prosound will fix it?
Or would I be better off thinking about building an arduinoboy with it's own power?