flash in 12at7

howardnair · 3523

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Offline howardnair

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on: September 23, 2010, 08:29:03 AM
odd!!  with the mullard cv4024  --i get a flash on turn-on--i do not with the EH 12at7--this occurs with 3 different nos mullards --other than the flash all is well---??????


Offline JC

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Reply #1 on: September 23, 2010, 08:35:50 AM
This is not uncommon in small European tubes.  It had to do with their filament formulation for "controlled heater warm-up".  I don't know the specifics of their approach, but I see it all the time in guitar amps with Euro tubes.

Kinda scary the first time you see it, though!

Jim C.

Offline Paully

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Reply #2 on: September 23, 2010, 11:45:16 AM
Yep, mine do it every time.  You're fine.


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