Ok so I have this three year old Vox AD30VT that has some weird issues.

For the past few months, it has been considerably noisier (hummm).

Also, after a few minutes of playing, it starts making this THUDDING noise...continuously. It doesnt stop until you turn off the amp and even then, it comes back really soon. It doesnt stop even if you turn down the amp volume to 0.

The frequency of the thudding goes way up if i turn the power controller down from 30 W.

Whats wrong with it?
Last edited by unet at Jul 3, 2011,
IDK man, but my ad50 has been acting up too. It has even made squealing noises randomly. With a digital modeling amp like that it'd be hard to repair, so maybe you should go the way I did and buy a new amp.
If you don't have enough cash to purchase a new amp, I would suggest to try going to your local Amp tech and explain yout situation. A piece of advice, don't go to a large/popular brand shop to get you amp fixed as they will charge excessiev amounts (High mark up), so try and find a local tech if possibly.
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I have enough to get a new amp, but I'll be going to a dorm room or an apartment in a month or so, so there's no point buying a proper amp yet.

I just wanted this to use till i had to move and then I was going to sell it.
Do the problems persist through headphones? It may be worth investing in a new amp and then using the Vox as a silent practice amp in the meantime. If the line out is fine then it can still be hooked to computers or a PA if needs be.
It's an opinion. It's subjective. And I'm right, anyway.
I used to have an AD50VT and I had a simular problem - simply do a reset and I bet you it will sort it out.

Here’s how you can restore the factory settings.
NOTE: If you do this, the programs you saved in the channels will be completely erased,
and will be reset to the factory settings.
NOTE: Effect and noise reduction settings made in the Manual mode will also be erased.
1. Turn the power off.
2. While holding down both the CH and WRITE buttons, turn the power on.
When the CH1 and CH2 LEDs begin blinking, release these two buttons.
HINT: If you decide to abort this operation, press the TAP switch at this point.
3. When you press the WRITE switch, the CH1 and CH2 LEDs will change from
blinking to lit. Initialization will be completed in a few seconds, and the amp
will switch to Preset mode.
NOTE: Never turn off the power while initialization is taking place.
Last edited by BlacktopStrat at Jul 5, 2011,
Okay...I tried the whole procedure, it went exactly as you described. (thank you!)

The noise has reduced considerably, which is odd...but the thumping came back after a few minutes of playing

I'll have clips of it up in a minute

Here you go. iphone quality.


Have you tried changing the tube/valve?

You should change it anyway after 3 years of use.

I would try that next.
Yeah the way the sound fades in if you play when the noise is happening makes me think it's a tube issue as well.

I don't have any 12AX7's on hand atm....I'll ask a friend.