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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: RE: 300B svetlana posted by Tre' on November 5, 2014 at 15:56:22:
I guess the problem is related to all Russian 300B.
A friend had a pair of 300B fail with broken filaments after some use in a 300B amp made by some local tube amp guru (most are Munchausens).
I always suspected the issue was caused by high in-rush current, and when after some time I did get a chance to check that issue, I was surprised to find that the supply was voltage regulated with 7805s limited at 1.5A: skipping on the sonic merits or faults of such solution, I have to admit that voltage and current were correct and very unlikely to be the cause of the problem.
The tubes were marked with the Reflektor factory logo.
He later acquired a pair of Sovtek 300B, and I was actually surprised to find that the basic construction of those 300Bs is identical (plate shape, filament suspension, etc) to a pair of EH300B I sometimes use (to the point that besides the base type and color they seem identical), and of course share at least the same suspension with the old Reflektor pair.
It seems to me that similarly to Chinese 300B tubes which under several brands and flavors come from the Shuguang factory, Russian origin 300B tubes are either made in the Reflektor factory, or with tools eventually taken from that factory.
As for the cause of the filaments breakage, it's probably materials quality, not necessarily the technical solution used for the suspension. The unpredictable lifetime comes from different production batches and poor purchasing standardization.
******
http://rh-amps.blogspot.com/
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Follow Ups
- RE: 300B svetlana - Alex Kitic 23:06:43 11/08/14 (2)
- RE: 300B svetlana - Tre' 21:29:59 11/09/14 (1)
- RE: 300B svetlana - Alex Kitic 02:35:55 11/10/14 (0)
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