12AT nos , flash at start ?


hi, is normal, when i start nagra pre, tube 12at7 make flash ?

like this

https://www.youtube.com/watch?v=PBjWmeuDurk
mati1979
Yes. It’s fine. Mullards?
My brimar 6060 (equivalent of 12at7) do the same
Yep, normal.  
Agree with the posters above. It is normal with Mullard 12AT7 tubes. I saw the flash when I had a pair installed in my Jolida 502P amp.
Perfectly normal in a Nagra preamp. (Full disclosure; am US service center for Nagra)
When you see that flash, its the flash of quality.
I have a couple of sets of NOS Mullards and a large part of why I like them is the flashing on startup…they sound great also, but the flash is simply a wonderful thing. Gold Pin 6201s…el flasho mundo.
yep mullard flash for me too!  Enjoy the show.