Basic EL34 and 6sn7 tube recommendation.


I have a Mystere IA-11 tube integrated amp from sister company PrimaLuna. I bought it preowned and like-new 1.3 yrs ago and enjoy it immensely. It is outfitted with Electro Harmonix EL34 and 6sn7 tubes. (Upscale Audio is the US distributor of Mystere and PrimaLuna and also an EH supplier.)

Everything is fine currently, so I enquiring if I should replace with the same EH tubes when it's time, or should I use another moderately priced brand. I have no inclination to compare and roll tubes looking for the best match. Just looking for a good solid recommendation to plug and play.

On another related issue, my amp has Primaluna's auto-bias circuitry that automatically adjusts the tube bias, so how will I know when tubes are at the point of needing replacement, unless they are burned out completely. Thanks.
128x128mjcmt
MJC, the KT77 should be a drop in replacement but to be safe I’d call Upscale, they are tube mavens

Thank you. I think I will call Upscale Tuberist. I suspect Upscale recommended the EH tubes to replace the stock factory Chinese tubes the amp came with.
A tube that is so underrated is the JJ EL34L ...In my amp I much prefer it over the GL KT77. If you can use KT66 variants, also consider the Reissue Tungsol 7581a. Viva Tubes is where I buy my power tubes, great service.