[SBranson]

Just a couple questions as I try to diagnose a hum in my system.

I have Woo Audio WA7 and Abyss Diana. I can hear the hum from the amp itself and from the headphones.

1. Is a ground loop hum reactive to volume? In my case the hum is not affected by the volume control

2. Would removing the ground wire from the outlet eliminate a ground loop hum? I tried this as an experiment and again no change.

This is my last attempt at solving my issue before sending the amp off under warranty.

Thanks

PS.. it’s not DC on the line

 

[endless402]

any dimmers in your house? though it would only be active when the light is on.

also try it at a different location, like at a friend's place or a neighbour's place.

 

[ferorake]

Looks like a tubes problem.
Did you try with a full portable system using a single electrical socket?

 

[dunring]

Do you have a 3 prong extension cable to try an outlet on a different circuit breaker?

 

[Davesrose]

Well I've had issues with ground loops at my home (which is very close to a radio tower). I have an old OTL headphone amp that will always pick up the radio station (no amount of experimenting with cages, RFI filters, isolators did anything). I just gave up and never use it at home (instead I have an iCAN). Other amps such as for my main speakers do fine with a power supply with RFI. My current plate amplifier with my subwoofer did get a hum with anything I tried....until I got a ground isolator from Blue Jeans. Don't know if your situation is similar in which you might be close to some source of extreme interference. The easiest things you can first try is ground loop isolators for the input or headphone output.

 

[gimmeheadroom]

Well I've had issues with ground loops at my home (which is very close to a radio tower). I have an old OTL headphone amp that will always pick up the radio station

I don't mean to contradict you, but that's a receiver, not a headamp. Try to look at the positive side

Anyway, that's induction, not a ground loop.

 

[Davesrose]

I don't mean to contradict you, but that's a receiver, not a headamp. Try to look at the positive side

Anyway, that's induction, not a ground loop.

Read my post again. I said tube headphone amp and plate amplifier for subwoofer. The original headphone amp and my HT receivers pick up the radio station. The amp always does no matter what I've tried. The receivers have been remedied by a good enough surge suppressor with RFI filter. I don't use the headphone amp, and use another that has a design that doesn't pick up the interference. My subwoofer's hum was resolved with a ground loop isolator.

And ground loops can be induction:
"A ground loop typically occurs when one or more pieces of your entertainment system are plugged into the AC (alternating current) at different locations, then connected together by electrical (versus optical) signal cables—RCA, HDMI, composite, component—whose shielding is connected to ground. In the simplest terms, this creates a single-loop antenna that just loves to suck in various types of noise via electromagnetic induction. You can see how a loop is created in the diagram below."

Quote from article that does go over various methods for isolation: How to get rid of hum and other noises from your audio, video systems

 

[gimmeheadroom]

No need. Even without a ground loop, a box full of tubes and inductors can pick up radio stations. The fact you have a receiver is no proof of a ground loop.

 

[Davesrose]

No need for word salad.

 

[Whazzzup]

why do you think ground loop? Got old bad mains?

 

[bigshot]

Ground issues are a hoodoo. Difficult to get any rhyme or reason out of them. I've always just tried grounding in different ways until I find a solution.