I have a VOX AD30VT that I am perfectly happy with right now. However, I have a buzz in the speaker? Any suggestions? Purchase a noise gate perhaps? Or is there a problem with the amp?

I have playing mostly with Artcore (humbuckers) lately. I do have a TV and PC in my practice space.

Thanks in advance for any info.

Is the noise the same with different guitars? When you turn up the volume does the buzz increase in volume at the same rate? Any buzz with the volume all the way down?

Ya, like Blue Tone80 said, does it make the same noise when you unplug from the input? If it does, it's a problem with the amp. If it's gone, then get a noise gate/ shield your stompboxes and patch cords from AC (moving them away from AC sources saves about 50 bucks in expensive cords... and works better IMHO)
It could be an issue with the "low-wattage power tube circuit". Look at the tube and see if it has any burn evidence on the platey things, i can't remember what they're called. (i had this happen to my amp and it sounded like a buzz) If the tube has a problem, switch it out, re-bias and it should be cool.
If it's a problem with the amp then you might just want to take it in to get sorted out. It could be a problem with the speaker if it's a buzz... but it could be something else too. buying a new speaker and having the same problem would suck.

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Thanks for the advice. Yes, the buzz goes away when I unplug the input.

I believe I need a noise gate. It is an ungrounded outlet (old house). I have to use a 3 prong to 2 prong adapter, which I do "ground" by screwing the plug in.