[Harp-L] TUBES REPLACEMENT FOR FENDER BLUES JUNIOR AMP

["Gianfrancesco Leone" <gianfrancesco_leone@xxxxxxxxx>]

I'd like to replace any or all the pre-tubes of my Fender Blues Junior for playing harmonica.
Someone suggested the following: 12 AT7, 12 AY7, 12 AU7 (but I do not remember exactly in which position (V1? V2? V3?...)
Anyone knows if is better to use the vintage american such as RCA, Silvania, General Electric an like, or the new ones such as JJ Electronic, Electro-Harmonix, Sovtek and like. I also knew by www.harpexpress  about a J J Electronic upgrade kit for Fender Blues Junior:
ECC81 - ECC83S - ECC832.  
Anyone ever tryed this JJ Electronic kit ?
Thank you in advance for your advices.
Bets regards,
Gianfrancesco 
Rome
Italy.