Vox AD15VT sound problem

[roslih]

Hi, I'm new here. The amp is about a year old. The problem I am having now is that the sound is distorted and does not sustain. it's fading off and buzzes after you strike a note. More obvious when you play chords. It gets worst when I increase the gain setting. Could it be just a simple pot problem ? It happens on all the modelling amps I select. Not so obvious when I play it clean. here's a sample of the sound. Take note of the tail end of each note. It starts buzzing Can anyone help......

http://www.imeem.com/people/L9wrJri/music/xgzsD9ii/sounds_from_a_ad15vtwma/

[Twist]

Sounds like your speaker is bad. Possibly the voice coil has warped and is rubbing.

[roslih]

Thanks for the tip. btw, I've tried using the headphone and it's the same problem. So, i guess the speaker is not the problem

[Mars Amp Repair]

Hello,
Well I guess the 'hold the amp up to the phone & I'll see if I can fix it' doesn't work too well here! yeah, kinda difficult to determine from the sound clip, but still helpful.

If the amp has a 'send' jack' you could pump that signal into another amp & see if the issue is before or after the power tubes. Be careful, as some of the line or amp out jacks are actually just 'emmulated' outputs derived from the speaker output which won't help you isolate the problem.

At the very least, you could try swapping the power tubes, if you have another set handy.

Also try balling up your fist & banging on the amp as the chord fades & see if that makes any difference. It could be a funky connection somewhere in the amp. glen

[Enzo]

Um...

This is one of those digital monstrosities. Has an LM3886 power amp. No power tubes. Ther is one tube in the preamp. Certainly worth a quick swap there to be sure.

I wish I could be more help, but I absolutely hate these things. The big AD60/120 most of all.

[acorkos]

i had one of those that sounded like the way yours does. like enzo suggested, it had a bad power amp chip. replaced it and it was good as new.

[roslih]

Hi guys, I m truly grateful and really appreciates all the kind advice given (although i wish I cud let you listen over the fone like suggested, but I am in SINGAPORE....now that's going tough isn't t...bearing the time difference and all...) anyway, I cranked the gain gain vol and master vol almost to the max (i lived in a flat (apartment)..so i didn't want my neighbors to call the police (it's pretty damn loud you know !!) and guess what ????...the problem's gone !!! Rite now although I am happy I have somewhat "solved" the problem, but is still clueless about what the problem was. Could it be just some loose connections or was it the preamp tube that is maybe "acting" up. I have an AD30VT. If the problem crops up again, I will try to swop the tube. Btw, can I use a 12AX7EH (taken from my Marshall AVT50 for this amp...sorry for this noob question, I am really new into all this stuffs)...anyway, thanks again....cheers