mapman, you are..never mind.
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Military/industrial grade NOS EL34 tubes would be very helpful, indeed. Do they exist ?
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I do buy tubes from Brent of Audio Tubes. From Tube Depot too, though their prices are high and choice is limited.
Medical/military/industrial must be more durable, reliable and longer lasting. They usually cost two/three times more, and as a collective expert opinion was expressed here - they might or might not sound better, could even sometimes sound worse.
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I just finished burning in new 12AU7 RCA black plates from early 50s to compare them to the RCA black plates from late 50s that I had installed. Both sets are matched.
Earlier RCAs do sound better !
They have a slightly higher resolution, more depth and charm. Fascinating.
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If they tolerate vibrations better , they should theoretically sound better, all other things being equal.
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trivema, no I have no intention to buy too many, just two or three sets of each type that I need. Did you compare those Raytheon 12AX7 black plates to RCA blackplates ?
Ralph, I see. This makes it complicated, doesn’t it ? You just have to try, no general answer really.
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But at the moment I am burning in a new set of regular 12AU7 RCA blackplates from early 50s to compare them to the same RCAs from late 50s. 25 hours of burn-in time so far, but I think I hear something indicating that they might be slightly better. Now, this is interesting, sounds crazy to non-audiophiles, I guess.
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By the way, I completely disregarded Kevin of VAC’s advice regarding small tubes. He suggested some selected Chinese for 12AX7 and Brimar or Sylvania for 12AU7. I figured we had different taste, and I certainly don’t want any Chinese tubes in my amp. So after talking to knowledgeable people here and beyond, I went with vintage 12AX7 Mullards for preamp and vintage 12AU7 RCA blackplates for driver tubes. I don’t really want current production EL34 output tubes either, something he suggested as well. At best, I hear that they don’t last, and at worst that they sound like crap. Perhaps it varies wildly, I simply don’t want to throw money away for virtually nothing.
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Well, Brent from Audio Tubes has both regular 12AU7 RCA black plates and military/industrial ones, all from 50s, not sure early or late 50s. He also calls industrial Command Series. I have regular ones installed, so I could order a set of military/industrial, burn them in for 100 hours and then compare. Return them if I hear no difference and lose 20% which would not be much, those tubes are $99 each and I would need three of them. I just don’t want to start with this and don’t want to buy more tubes right away, last week spent $450 for a matched pair of 12AX7 NOS Mullards longplates from 50s. They are excellent tubes, hard to find, so I bought a spare pair from Brent.
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Yeah, no doubt, NASA grade, medical grade, scientific grade. But also for guitar amplifiers, organs, TVs etc.
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And to go a little further, military grade and industrial grade - any difference ?
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