Buzzing noise when USB is disconnected

[ignaciopl]

Hello everyone,

I have adquired a HX Stomp from a friend 3 months ago. I'm using it only to practice at home with headphones and always connected to PC with USB. In the last weeks I've noticed a annoying buzz ground noise that makes me want to stop playing, very irritating playing with headphones... My surprise comes when I disconnected the USB cable and that ground noise is louder than before! What the hell is happening here? It happens in every rooms and plugs of my house.

I also tried to connect the Stomp to a USB audio interface (through the L MONO Output) and when the USB is plugged to the audio interface it's OK , but when i disconnect the USB from the audio interface the noise appears again.

 

The Stomp is out of guarantee so I can't use it, but I think that this is not problem of my unit. Any idea here?

 

 

The power supply I'm using is the original that came with the stomp (CUI INC DC-3)

 

Thanks!!

[rd2rk]

I'm going to assume that all of your devices - Stomp, amp, PC - are connected to a quality Surge Suppressor with EMI/RFI filters. That's basic.

Since it happens everywhere, even when USB is not connected, Check all of your cables and your guitar for shorts.

A cable that was good last week could have been kinked or run over by a chair (chewed on by the cat), your guitar's input could be loose or damaged, a solder joint could be failing, a pot could be bad, you get the idea. S#&t happens.

You mentioned headphones, but not other amplification systems. Check that stuff too.

Next, think about what changed in your house in the last couple of weeks. New appliances, rheostats, wireless devices, moved routers (should be at least 10 feet away).

Having the Stomp too close to your computer or a cell phone can also cause interference.

If you live in an apartment, it could even be something new that your neighbor is doing! Not likely, but not impossible.

Of course, it could just be a bad PSU. Hard to check that if you don't have a spare, but if all else fails....

Lastly, worst case scenario, your Stomp has a problem. Contact support. Even out of warranty, L6 support has a certain latitude in dealing with device failures not caused by obvious abuse. It's worth a shot.