NUAD - 59 Bassman LTD has arrived( begin tube rolling)

Love mine that I bought new about five years ago. I have a set of matched JJ 6L6 tubes and want to re-bias with them. Never done it before. I have the Eurotubes instructions, meter and such. The tube clamps are a pain. I keep putting it off.

Congrats!

I like the RI Tung Sol 12AX7 as far as new tubes in a Fender.

Usually in only swap V1 these days.

If you try a valve rectifier, bear in mind it’s a hot switching standby, so avoid using standby with it. Every time standby is flipped into operate mode, there’s a large current surge through the rectifier.

The 30W anode dissipation limit of the 6L6GC is traditionally derived under the design max rating system. That system puts the onus onto equipment designers to apply a derating before putting that limit into use, in their calculations.
Hence my understanding is that valve types with a ‘design max’ anode limit require that limit to be derated before applying the ‘idle at 70% of the anode limit’ guideline.
About 26W looks about right for 6L6GC, so don’t idle them hotter than 18W.
Alternatively, use 60% as the limit for design max rated valve types, as the numbers work out the same.
That’s what a lot of techs had concluded themselves anyway (ie idling at 21W seemed too hot for 6L6GC).

Beware of trusting your perception too much; a valve’s transconductance increases with anode current, so 70% will always be a bit louder than 60%, and our hearing perception tends to be that ‘a bit louder’, all else being equal, gets perceived as ‘sounding better’, rather than just ‘louder’.

A few years ago I did some experiments with idle dissipation and bias adjustment. On the amps I did this, I biased to the 70% “rule” as prevalent across the innerwebs. I played the amps for a while and the calculated and adjusted them down to 60%. 60% sounded great, so that became my seat-of-the-pants number. Below 50 and the amps sounded sterile. The tubey magic left the building.

Btw - many JCM 800 amps were biased pretty cold out of the factory. I suppose that kept warranty claims for output tubes down. Those amps benefited greatly from a proper bias adjustment.

So after some experimenting with the bias , I went from 50 percent to 75 percent dissipation just for farts and giggles, I decided to keep the original 70 percent with a bias at 37.8 ma. The closer to 50 percent , the more uninspiring and sterile it sounded. It sounded less tweed like at 60 percent than at 70 percent. I really like these tung sol tubes and will keep them . I’m going to order some tung sol preamp tubes and compare them with my JJs I have on hand.

This amp sounds great with all my guitars, but with a strat it is pure magical. Same with my 335, but to a lesser degree.

I had a Victoria version. Easily one of the best 2 amps I've owned.

It is glorious isn't it? Sure makes me sound better than I am!

So the tube rolling continued. The preamp tubes seemed a tad noisy and a little tired. I had some JJs still new in the box. I put in all new 12ax7s and a new rectifier tube. What a difference . Not only does the clean sound better (crisper) , but the crunch sounds even better. I guess I really like JJs in Fender preamps . I’m sticking with the Tung Sols though for power tubes though. They sound great.

That could be true . I’ve only mostly owned Fender amps thus far. I still have the stock tubes in my Marshall dsl and my only other non fender amp I had was a peavey Classic 30 for about 3 days.

The JJ long plate is the ecc803s. I like ‘em in heads (V1 position - I usually don’t mess with the rest except maybe the PI). I’ve never had much luck with long plate tubes in combos, so I don’t even go there these days.