Gorm Posted July 19, 2019 Share Posted July 19, 2019 Hi guys, A problem developed with my Ampsandsound Stereo 15 tonight. When I started it for the first time since last weekend, there was now a noticable feedback buzz instead of the usual dead silence. As i approached the unit, I discovered that the feedback became louder when I moved my hand towards the 12AX7 position. As I moved my hand back and fourth from the 12ax7 I could control the "volume" of the feedback. So, I powered down the unit and replaced it with another 12ax7. It also exhibited the same behavior. I don't believe this is any sort of ground issue, as it was perfect for nearly half a year before today. Anyone have any ideas? Quote Link to comment Share on other sites More sharing options...
richieb Posted July 19, 2019 Share Posted July 19, 2019 ^^^^^ ==== I think it best to get with Justin Weber, the amps builder. He should know better than anyone here — 2 Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted July 19, 2019 Share Posted July 19, 2019 Just in case.... if you have any lights on a dimmer circuits try turning them off and see if noise stops. miketn Quote Link to comment Share on other sites More sharing options...
Gorm Posted July 21, 2019 Author Share Posted July 21, 2019 I ended up shipping it to Justin. I could slightly tape the 12ax7 tube and the sound immediately reflected in the speakers. I was able to replicate this behavior with multiple 12ax7 tubes. Quote Link to comment Share on other sites More sharing options...
Schu Posted July 21, 2019 Share Posted July 21, 2019 So it WASN'T a bad 12a? Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 22, 2019 Share Posted July 22, 2019 Could just be a bunch of microphonic tubes... I had some 6922 tubes that I had to filter through to get one that was quiet and non microphonic. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 24, 2019 Share Posted July 24, 2019 I haven't received yet, Ill get it on the bench and will find the culprit. Im my experience... 150+ amps or so, less than 10 have every had anything actually wrong with the amp... tubes tend to be the culprit. Either way Ill have her back to singing ASAP. Quote Link to comment Share on other sites More sharing options...
Schu Posted July 24, 2019 Share Posted July 24, 2019 ^now that's nice! Quote Link to comment Share on other sites More sharing options...
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