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Hello all.
I have a mid '60s Vox tube Berkeley I have owned for about 15 years. I recently noticed a volume loss of roughly 20%-25%, and slight change in tone (mainly mushy low end, lack of punch). I figured it was power tubes so I replaced them with new EH EL84s. It didn't make any difference. I've done a little work with tube amps so I opened it up and checked all the basic stuff but didn't find anything. I didn't really have time to mess with it so I took it in to a highly recommended tech. He checked it out, put it on a scope, etc. and said he could not find any problem. I brought it home but the issue is still there. Does anyone have any ideas or suggestions as to what to look for?
The caps were changed about 7 years ago. and I've tried replacing all the tubes with known good ones. Tried different speakers. Even tried a different output transformer. (I have the original and a Mercury Magnetics upgrade).
One other thing - Last spring we used this as a back line amp for a garage rock festival. Sometime during the show one of the 2 EL84s went bad. I don't know how long the amp was played with the tube out but it could have been 2-3 hours. However, The problem didn't seem to show up until several months later.
Thanks,
Kirk
I have a mid '60s Vox tube Berkeley I have owned for about 15 years. I recently noticed a volume loss of roughly 20%-25%, and slight change in tone (mainly mushy low end, lack of punch). I figured it was power tubes so I replaced them with new EH EL84s. It didn't make any difference. I've done a little work with tube amps so I opened it up and checked all the basic stuff but didn't find anything. I didn't really have time to mess with it so I took it in to a highly recommended tech. He checked it out, put it on a scope, etc. and said he could not find any problem. I brought it home but the issue is still there. Does anyone have any ideas or suggestions as to what to look for?
The caps were changed about 7 years ago. and I've tried replacing all the tubes with known good ones. Tried different speakers. Even tried a different output transformer. (I have the original and a Mercury Magnetics upgrade).
One other thing - Last spring we used this as a back line amp for a garage rock festival. Sometime during the show one of the 2 EL84s went bad. I don't know how long the amp was played with the tube out but it could have been 2-3 hours. However, The problem didn't seem to show up until several months later.
Thanks,
Kirk
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