VT 50 tube keeps failing « VOX

Member

I've had my VT 50 for about 3 years. Get's light use ... 7 gigs and probably 30 practices in that time.

About 3 weeks ago plugged in and got almost no volume out of main speaker and very distorted amp sounds. Each amp and preset was different but scratchy, distorted and very faint volume.

Tried the headset and everything sounded great. Tried several factory resets -- no luck -- same problem.

So on a hunch replaced the 12AX7 tube and ... viola ... volume back to normal.

Unfortunately 4 practices later and bam it is back to very low volume fuzz. Suspect the tube is shot again. I could and will need to replace it but, need to figure out what is causing it to fail. My bro who has had tube amps for many years is surprised and says that these types of pre-amp tubes rarely fail.

Any suggestions?

Posted 9 months ago

cosmicrepairdude

Member

The tube is probably fine. The tube socket or some other connection may be gummed up. You might need to do what I suggested for "snare noise" at http://www.voxamps.com/forum/topic.php?id=3716&page=19 in my first 2 posts on that page.
You can check the tube by borrowing one from a friend who has a tube amp and swapping it in.

Posted 9 months ago

miked65

Member

cosmicrepairdude - thanks - I will give that a look and a try

Posted 9 months ago

timc

Member

My bro who has had tube amps for many years is surprised and says that these types of pre-amp tubes rarely fail.

and in a VT they are likely to last even longer than in a real tube amp as they are not subject to an significant heating or high-voltage stresses.

Posted 9 months ago