well congrats on the no-hum issue, that one seems to be real hit or miss with users even with the same version of T10-11 , etc.dnepro wrote: 1) Is changing the tubes likely to mellow out the harshness of the uppermost range?
2) Is it necessary to change all the tubes to 12ax7, or could I replace the tube with the most significant effect on tone as a trial (leaving the others as 6n2's) and switch the others later if improved?
3) Is matching tubes necessary - or is this a guitar amp issue?
4) Is purchasing 'tested' tubes highly recommended, or a disposable luxury? (Ignoring the obvious irony that this whole pursuit is a disposable luxury)
I suppose there is also the question of upgrading the rectifier tube, which although I understand should theoretically have limited impact on sound, I have read some people think it does.
I'll take crack at your 4 but opinions ill vary
1) I would not expect a significant tonal balance shift from tube-rolling to a boutique tube versus Asian. I've never done it with my T10, but I noticed very little difference in the past. I put in a very expensive NOS 1950's GE 12AX7 that cost me $75 (tested to be at spec.)
now selling for $119.
into a Bellari and difference was so subtle as to be barely noticeable. My T10 uses a stock Chinese 12AX7 and the tonal balance is beautiful,
so might it be a tube type issue, yes possibly,
versus a tube manufacturer issue? unlikely IMHO.
2) The tube that does the most work in this circuit is the first one, the one farthest from the RCA output jacks. Can you put a 12AX7 here and switch while leaving all the others 6N2, probably, but others here would know better.
3)I do not see how matching tubes in a circuit where they are run in series can make any difference at all.
4)My $75. GE tube really felt like a huge waste of money, and still does. Next step down is some Amperex bugle boys at $120. for the set of 3, still too much. My next tubes, after the stock ones go bad, is a set of Russian Gold Lions and they will need to be a good deal, like $60. for all 3 .