I really really love the wooden dock, but have one problem: I get a buzzing noise when it's plugged in, but the empeg has been removed.

Note: the stereo outs go to a small behringer mixing board, which feeds a pair of self-powered monitors (KRK V6s).

If I unplug the dock from power, the buzz goes away. If I dock the empeg into the unit, the buzz goes away. If I unplug the dock from the board, the buzz goes away.

The only thing I can think of is there's some sort of ground loop problem between the A/C adapter and RCA outs when the empeg isn't installed.

Any ideas on how to remedy?

-brendan

The RCA leads are acting as antennas to pick up the AC hum from the AC adapter. You can probably eliminate it by connecting the AC adapter jack's ground to the RCA jack grounds inside the dock -- by default they do not touch anywhere in the dock.

EDIT: Yup, that was it.. I just tried this on a dock here. Any future docks I make will have this connection wired in from the factory.

Cheers

Nice catch with the antenna thing, Mark.

Brendan, another possible thing to try: I've had buzz/hum problems with the AC adapter get solved simply by switching adapters. I had the sunpower brick over at a friend's house and it buzzed with his stereo. When I switched to a different adapter (in this case the compact plug-top adapter), it worked fine with no buzz.

Thanks guys, I'll try the ideas out and report back.

-brendan

> EDIT: Yup, that was it.. I just tried this on a dock here. Any
> future docks I make will have this connection wired in from
> the factory.

Earlier today, I wrapped a wire around the barrel of the DC side of the power cable and one of the RCA posts. Buzz gone. Unit still functional. No fire. Thanks. Perhaps I'll make it permanant...

Of course, I was just sitting here, wondering why the remote isn't working over my shoulder. Oh wait, forgot to put the empeg back in, since I wasn't prompted with the annoying buzz when I got home from the gym.

I'm curious about theories of why I'm the only person who'd reported this problem?

-brendan

PS - Before and after the extra ground wire, I was using the riocar power supply...that seems to match the description of "plug-top adapter" that got rid of Tony's buzz. There are other adapters?

> Earlier today, I wrapped a wire around the barrel of the DC
> side of the power cable and one of the RCA posts. Buzz
> gone. Unit still functional. No fire. Thanks. Perhaps I'll make it
> permanant...

strike that. when the empeg is out, it's now quiet, but...when it's in the dock, I get hard drive noise if the rca's are grounded to the barrel of the DC plug.

Can you repeat this, mark? If so, then you might need an interruptable ground in the next design: ground the rca's to the shield of the dc plug when the empeg isn't in there, but don't do so when the empeg is installed?

-brendan

I get hard drive noise if the rca's are grounded to the barrel of the DC plug.

Try moving the DC power supply to a different plug to see if you can get rid of the ground loop by having the player on a different circuit than the mixer. Also, do you have any other suitable power supplies and can try them? What kind of power supply is your player using right now?

I have not tried to reproduce the HD noise you reported, but the solution for it will be the same as for the original AC hum issue: (EDIT) connect the HD tray to the empeg's shell with a grounding wire, thus connecting it to the RCA and AC-Adapter grounds, removing yet another ground loop.

Cheers

So you're saying none of the IDE wires are a chassis ground?

They're probably grounded, just like the RCA plugs etc... but not all at a single point to avoid this (unanticipated) grounding issue.

Cheers