Noise in the left channel with the vacuum tube switched on

[Animal]

Hello!

I recently bought an used Triton Extreme. I've been very happy with it, but now I discovered that there's a weird digital-ish buzzing noise in the left channel when the vacuum tube (Valve Force) is switched on. The noise comes from the left output on the back panel and from the left headphone as well when using the headphone jack.

I discovered it today, I'm 99% sure that the noise wasn't there before as I've used the keyboard quite much already.

Here is a sample of the noise (I did a mono recording of the left output only, cranked everything to max volume and normalized the recording so you can hear it better. It's not that loud actually, it's pretty quiet, but still very well noticeable):
https://www.youtube.com/watch?v=bnVUAdxaF10

At the end of the recording I turn the Valve Force off for a moment and as you can hear, the noise disappears.

Have you experienced something similar? What could be the problem?

Many thanks!

EDIT: I now found out that the noise is there only when I sit behind my laptop. The Triton is connected to a Lexicon Omega sound card which is connected to my headphones and when I'm wearing headphones and sit at the laptop, the noise can be heard. When I step away from the computer, the noise disappears. Connecting or disconnecting the USB cable of the soundcard makes no difference.

Still, why is that and why only the left channel?

[magilla66]

I’m just guessing here, but is the Omega on the left side of the laptop?

Move it to the right and see what happens.

Also, how far away do you have to move with the headset before the noise goes away?