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Post by Buzz Fretwear (Ignatius) on Nov 3, 2006 7:54:58 GMT -7
I should know better, but I just had one of those moments. On one hand I've seen the +/- 300 hour rule for replacing your power tubes, and then I saw a thread somewhere around here (I think Myles either started it or chimed in) where he sees some guys replace their tubes as often as 30 hours. I had been noticing that my amp was not quite as lively at the last few gigs but I was thinking it might be the room or my ear. I ordered a new set of Groove Tubes for my Mazerati direct from GT (Myles picked 'em for me) and WOW. Like I said, I should know better but I daresay my Mazerati has never sounded better. When I got it it had the stock GT's in it but who knows how long it had sat in the shop where I bought it and how it had been played. It sounded good, but a few months later I ordered a set of JJ's from Bob at Eurotubes. The amp seemed to wake up a bit at the time, but I really think these new GT's have made me hear the amp's full potential for the first time - and this comes after owning the amp for just over a year.
So, even though I should have known better, the moral of the story is: you spent your hard earned money on a great amp - it deserves great tubes and it deserves fresh ones.
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Post by myles on Nov 3, 2006 11:08:18 GMT -7
You have to remember that the GT EL84S is dynamically tested and not statically tested. This means the tube match has to be within certain specs across the operating range and not just at idle. This is pretty labor intensive and why GT stuff can be more pricy.
My personal "300 hour rule" as absolute MAX is just for cathode biased EL84 amps as a side note (or other cathode biased amps in some cases such as some EL34 amps cathode biased amps)
Grid biased 6L6 amps can go 6000 hours in some cases. EL34 grid biased amps about 1/2 that unless you have a Marshall DSL/TSL and follow Marshall bias instructions and run them to 45mA per tube which is way too hot and sounds way too harsh.
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Post by foxx on Nov 3, 2006 18:56:37 GMT -7
I love those GT el84's #5, especially if Myles picked them. He also picked a set of preamp tubes for my Mazerati, and it sounds better than ever. A few months have gone by, and maybe 100 hours at most, so the impact of new tubes has diminished a bit, but I would not hesitate to get exactly the same tubes again and again.
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