indieuncle Posted September 29, 2009 Share Posted September 29, 2009 I recently swapped the Sovtek EL84 with a JJ EL84. The JJ lasted about three minutes before burning out. I thought that the valve must be faulty and had it replaced. The same thing happened with the replacement. The original Sovtek still works fine . Has anyone had a similar experience or offer some explanation as to why this may be happening? Link to comment Share on other sites More sharing options...
RSDx Posted September 29, 2009 Share Posted September 29, 2009 I recently swapped the Sovtek EL84 with a JJ EL84. The JJ lasted about three minutes before burning out. I thought that the valve must be faulty and had it replaced. The same thing happened with the replacement. The original Sovtek still works fine . Has anyone had a similar experience or offer some explanation as to why this may be happening? Perhaps you just got 2 bad JJs ??? I've swapped some tubes, local shop sold me Sovtek that was DOA, had a Sovtek go bad (shipped amp, which was bought used, so dunno how old that one was or how hard it had been played. I've had Sovteks that lasted, have JJs that are still fine ..... I prefer JJs.....it's kinda the luck o' the draw, I guess...... tubes aren't the most bulletproof things ever invented, for sure Link to comment Share on other sites More sharing options...
indieuncle Posted September 29, 2009 Author Share Posted September 29, 2009 Yes, may just be bad luck, but they were purchased from a company that “…has become one of Europe's leading suppliers of tested, graded and guaranteed guitar tubes and valves to the professional music and audio industry.” So I can only assume that they were OK when they were sent out. I’ve used JJ’s successfully in my other amps (12AX and 6V6/ 6L6), no problem at all. I’ve had no previous experience with EL84 equipped amps though. Link to comment Share on other sites More sharing options...
Ricochet Posted September 29, 2009 Share Posted September 29, 2009 they were purchased from a company that “…has become one of Europe's leading suppliers of tested' date=' graded and guaranteed guitar tubes and valves to the professional music and audio industry.” [/quote'] If they're a serious company they should look into you're problem. If the Sovtek is fine, that could indicate a faulty JJ. Link to comment Share on other sites More sharing options...
indieuncle Posted September 29, 2009 Author Share Posted September 29, 2009 Just had a reply from the supplier who confirmed that the valve was tested and well packed (true) and seems to think that I’m cracking the valves when I install them. I find this very unlikely, as the Sovtek has been in and out several times. Oh well, suppose I’ll live with the Sovtek until it eventually dies. (Sounds pretty good anyway). Link to comment Share on other sites More sharing options...
m-theory Posted September 30, 2009 Share Posted September 30, 2009 That doesn't sound right at all. The JJs are very stout 6bq5s. That said, it is possible that your bias is so far out of whack, and your Sovtek is so weak, that the Sovtek can survive the abuse, because it's simply not able to draw enough current to kill it, while the JJs were drawing far more than they could handle. Either way, it's far from ideal, and really makes the amp all but useless as it is, imo. I'd definitely look into the voltages on that tube. Link to comment Share on other sites More sharing options...
indieuncle Posted October 2, 2009 Author Share Posted October 2, 2009 Thanks, I'll get it checked over before I spend anymore cash on valves. Link to comment Share on other sites More sharing options...
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