uniqueAndreas Posted August 17, 2018 Share Posted August 17, 2018 Hi guys, Yesterday I had a very bad experience when doing rehearsal with the band. Especially because we are going to have a gig tomorrow and the day after tomorrow. I won't be able to use this amp. After switching it on I was not able to switch to a preset that had distortion. I first thought it was a failure because of the pedal board so I unplugged the board. But apparently the same behavior was when using the channel switches on the amp directly. I figured that I could not even manually use the amp model knob correctly. Every time it seemed to have a distorted channel the sound was gone in a sec. Another issue bothered me. Even when the sound was clear sometimes I heard a knock-knock, similar as I would bounce the bass string onto the pick-up. Any idea what that problem could be? TIA Best regards from Germany, Andy :-) Quote Link to comment Share on other sites More sharing options...
psarkissian Posted August 17, 2018 Share Posted August 17, 2018 When was the last time the valves (tubes) were replaced? Quote Link to comment Share on other sites More sharing options...
uniqueAndreas Posted August 17, 2018 Author Share Posted August 17, 2018 Hi Psarkissian, To be honest? I did not change the valves at all. However I do not play very often. But now comes the surprise. I just put the setup together at home and voila it works like a charm! No clue what it was in the rehearsal room. Could it be that the amp does not work well with the speaker there? Nevertheless I am going to have a backup for the next gigs. If someone could shade some light on this it would be nice. I do not want to have this surprise the next time... Best, Andy Quote Link to comment Share on other sites More sharing options...
psarkissian Posted August 17, 2018 Share Posted August 17, 2018 Tubes should be change out (and biasing the power tubes) once every 18 to 24 months, depending on how much you use it and how hard you push it. Like care tires, once every 50,000 miles. When they get old and and the gas in the tube with it, weak tubes can leak current and pull down the supply line. And always use the specified tubes. These are not, all analog tube amps of old, so you can't get away with the same sort of mods and tube swaps like we used to do in the 1960's and '70's. Quote Link to comment Share on other sites More sharing options...
uniqueAndreas Posted August 18, 2018 Author Share Posted August 18, 2018 Hi Psarkissian, Thanks for your fast reply. I'll get it. I am going to let the valves change as soon as possible. But coming back to the problem that I described? Do you really think this was a tube problem? I wonder because the clean channel worked well. It was just that I wasn't been able to switch to one of the presets with distortion - well the distortion went away in a sec or using the left knob to switch to a distorted amp model. The solution for the rehearsal was increasing the gain - then I had distortion. Also if it was a tube problem why do they suddenly work again at home? I would bet it might be an electronical problem but I am not an expert. However I will have my backup tonight in case it happens again also tomorrow. And then bring this lady to the store for replacement and full check. Thanks a lot. Best, Andy Quote Link to comment Share on other sites More sharing options...
psarkissian Posted August 20, 2018 Share Posted August 20, 2018 It's distorting too soon at a lower gain,... what type and brand tubes are you using? The wrong one will give an incorrect characteristic curve and distort too easily. These aren't the all analog amps of old, digital and analog sides need to play nice with one another. Quote Link to comment Share on other sites More sharing options...
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