Recommend new EL84 tubes

NessTone probably are but they’re cheap enough to try and if they don’t work for you the investment is pretty small. I’ve used them for years and have had good service out of them. I liked them better than the Electro. Harmonex for what’s that’s worth.

LH:

Found it here, and it has to do with the bias design of the amp (so something to check out).

PS:

I played electric guitar from the early 60's to 1986 and, IMO, guitar amp reviews of tubes have little to do with how the same tubes will perform in HiFi amps.

DeKay

Sure, if the tubes are overdriven they won't last. Perhaps Kevin doesn't sell the Gold Lions. 🙄   In his video he's talking about putting an EL34 into an amp that is biased to run KT88s and so driving the plates beyond their rated max. dissipation.

I am considering the Gold Lion EL 84 because the Manley has provision to set the bias individually via trim pots. Have you heard these tubes? I am, of course interested in how they stack up to the originals

Jim McShane says basically the same thing but it doesn't apply to most consumer audio components including Manley. Jim references the Vox AC-30 and AC-30 clones; guitar amps that run the output tubes beyond dissipation specs. I know this to be true as I own an early 1966 Vox AC-30; bad ventilation to make matters worse. Guitar players call this design the "easy bake oven".

I have tracked down some Brimar/Marconi black plate 1950s 12AT7 but have not yet decided on el84s