When I had PL Two I mailed with the owner of the company and he wrote me that you can use any tubes together without any problems, cos their auto-bias system is the only one that can be called the real thing, each tube gets own bias, which allow you to use this combinations without problems. I used KT88 and 6550 all together, no probs what so ever. If you want less warmth and better extention both ways, go for NOS TUNG SOLS 6550 Black Smooth plates, with no holes, thats why they call them smooth. Or, even better, NOS GEC KT88, period, you just stop rolling after that, thats what I did and never looked back.
PrimaLuna ProLogue Two - mixing tubes?
I have a newer quad set of SED 6550Cs that I've been using as a replacement for the stock KT88 tubes. I decided to take advantage of the auto biasing feature of this amp and run one 6550 and one KT88 per channel, only because one of the stock KT88s is bad. I'd like to use up the other two good KT88s. I've read that this is acceptable with this amp, but I'm not sure if this will have negative impact on the 6550s. I plan to rotate the 6550s so that I still have a somewhat matched quad set of them. Has anyone done this before, and are there any pitfalls I should take note of?
Thanks
Thanks