Re: What brand of tubes?
Definitely with NOS. Ei would be a good choice, but personaly, I'd go with that one below :
(from ww.kcanostubes.com)
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N.O.S. Tesla (NOT JJ!) EL84s $50 Per Matched pair
1970s vintage. Best deal in NOS EL84s. Higher gain and more bite than JJ EL84s. Excellent in your Blues Jr., Marshall 18 watt, Matchless, Bad Cat, Vox AC-30, AC-15 or Dr. Z amp. hi mike -- my tubes were waiting when i got home from work yesterday, and your recommendation of the NOS Tesla (non-JJ) EL84s was spot-on -- rich and balanced, perfect breakup threshhold! thanks for your excellent service, including the advice -- that's real value-added! woody mitchell. Hi Mike:Great tube!!! Very clean and sparkly compared to the stock Sovteks that came with my amp. I’m getting some great bell like tone out of them. Very smooth and defined when they break-up. Eddie S.
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Otherwise you could try Ei, but they are not as tough as others.