Strange hum issue...

18watt · Post by **18watt** » Tue Jul 01, 2008 2:23 pm

My Voyager OS seems to introduce "hum" from its audio out, even when powered off. Not huge hum, but it's always there in the background. I've tried plugging it into various powerstrips, and directly into the wall, without success. The hum goes away when I either (a) unplug the power cord, or (b) unplug the cable. I've tried a couple of different cables, all Mogami Golds.

I'd be very grateful if someone could help me de-hum my VOS!

Thanks.

johnypneumo · Post by **johnypneumo** » Tue Jul 01, 2008 3:49 pm

to me it sounds like the moog and your mixer are plugged into different mains supplies or different mains extension leads etc,.
hence theres an issue with the earth between the 2 units

18watt · Post by **18watt** » Tue Jul 01, 2008 4:37 pm

Here's the catch, though: if I plug everything into the same power strip, same issue.

I'll try to isolate the issue further, I know debugging ground loops and stuff over the interwebs is tricky.

MC · Post by MC » Tue Jul 01, 2008 5:31 pm

Try lifting ground on the OS using a two prong adapter.

18watt · Post by **18watt** » Tue Jul 01, 2008 7:12 pm

I'll give it a try. Cheers.

c7sus · Post by **c7sus** » Tue Jul 01, 2008 8:42 pm

The Voyager manual seems very clear and concise about this point:

"This product must be grounded."

18watt · Post by **18watt** » Wed Jul 02, 2008 8:29 am

I didn't get around to trying, anyway. I reorganized my room, and something in my setup changed - the hum isn't present right now. Weird.

MC · Post by MC » Wed Jul 02, 2008 1:17 pm

c7sus wrote:The Voyager manual seems very clear and concise about this point:

"This product must be grounded."

There are exceptions to this. With the high number of interconnect points on the Vger it is very easy to encounter a ground loop that causes an audible hum.

It usually doesn't hurt to lift ground on the Vger, but the last place to lift ground is any high power component like power amps.

I did some temporary tech support for Moog a few years ago. A customer had this exact same problem, and my ground lift suggestion solved the problem with Moog's blessing.

c7sus · Post by **c7sus** » Wed Jul 02, 2008 8:20 pm

I'm a commercial/industrial electrician with nearly 30 years experience.

Anytime I see advice on the interwebs about grounding my ears perk up a bit. I've seen some pretty far-out suggestions about overcoming either the lack of a grounding conductor or conversely the lifting of ground(s).

Audio hum comes from a variety of sources. What would be tragic is somebody mistaking a faulty neutral for a grounding issue and frying themselves or everything in the house with 240v by lifting the only remaining path to ground. When you lose your "grounded conductor's" ground reference bad things happen. Like the magic smoke escapes all your kewl electronics............

YMMV. Proceed at your own risk!!!

jgirv · Post by **jgirv** » Mon Jul 14, 2008 5:42 pm

actually, I had a similar problem with the Little Phatty... amazingly, when I plugged in the USB connector (even though I wasn't using it) to the laptop, BAM!, no hum. None. So these ground loop situations vary widely depending on what's connected to what. And, yes, I had everything going through the same power strip, too.

till · Post by **till** » Tue Jul 15, 2008 4:26 am

Tried two DI boxes with a ground lift switch yet?
Or try to unplug the all the cables (except the mains and the audio out) and insert the cables one by one till you get the hum.
If the hum is also present if the Voyager is just connected to the power and a headphone, then there is something wrong with the Voyager itself.

I would not change a thing on the three prong mains cable.