VTL tubes 6550A,B,C, WA or WB?


I'm using VTL MB250sig, what are the tubes that VTL using and the differences between those tubes...

Thanks
hi5
It seem that I hardly get an answer regarding VTL....
Hi Hi5,
Current production VTL amps are using SED winged C 6550C.
http://www.upscaleaudio.com/SED-quotWinged-Cquot-6550C_p_16.html
These are IMHO one of the best current production KT88/6550 tubes.
Regards.