Old_School
Well-Known Member
My w30 was layed up for a while, as my main system evolved to the point where it didn't have the inputs I needed, believe it or not (mainly a tape loop). I've pulled it out now and plan to use it as the center piece of a second system, and I was wondering about tube rolling.
When I had it in use I had some bad luck with a couple of quads of KT88s I tried, but it worked fine with a quad of old GE 6550s. Given the value of the 6550s, I'm considering cashing them out, so I was wondering a few things about rolling tubes that are not as close in characteristics as the KT88/6550 types.
First question, do I have to set the bias point differently? If so, where's a good start for EL34s (I have a new Quad on hand, so they'd be the first to try)?
Is the amp capable of using KT90 or KT120? I would think the former would probably be a "yes" as they are fairly close in characteristics to KT88, but I'm not sure the amp has enough grunt for KT120s.
When I had it in use I had some bad luck with a couple of quads of KT88s I tried, but it worked fine with a quad of old GE 6550s. Given the value of the 6550s, I'm considering cashing them out, so I was wondering a few things about rolling tubes that are not as close in characteristics as the KT88/6550 types.
First question, do I have to set the bias point differently? If so, where's a good start for EL34s (I have a new Quad on hand, so they'd be the first to try)?
Is the amp capable of using KT90 or KT120? I would think the former would probably be a "yes" as they are fairly close in characteristics to KT88, but I'm not sure the amp has enough grunt for KT120s.