Tube amp question

When I spoke with Jarred about this while helping a friend on his, they were open to the idea of running other tubes in the F22 yet there was little feedback and what the amp was really optimized for other than EL34s, originally.  For the little extra "kick" you are looking for, that's why I was recommending a slight jump up to nice KT88s [for this particular amp]. Who doesn't have 3-4 different sets anyhow, lol. :)   

Thanks, I'll see how the KT150's shake out and I may consider that.

So now we hear that the OP and one other member has had the same problem when running KT120's. The amp went into protection mode. I would think if it does that with KT120's...nothing good can happen when you roll in KT150's.

What concerns me is that some of you are telling this person to bias to a certain level on his amp. It should be noted that bias levels are not universal from amp to amp. No Hickok ever made will properly test most power tubes which would include 6BQ5s. Now this doesnt mean that a tube wont continue to be linear as the plate voltage is increased from tester to tester, but most suitcase testers will not give you an accurate reading because they dont test at real world operating levels. 

 

For the record I do not like amplifiers that can accommodate a wide range of power tubes. Some have pointed to the possible problems and shortcomings of such designs. However, when in doubt it is a good idea to listen to what Ralph at Atma-sphere has to say on the subject.

best performance and sound quality will be had with the EL34 or 6550 tubes, that no extra wattage will be achieved since the transformers are the limiting factor.

As I suspected. 

I biased them at 50mv per the manufacturer spec. I slowly raised the volume and after about 10 seconds the amp shutdown in protection mode.

Even biased at 50mv, it sounds like they are drawing to much current for the transformers to supply. Stay with EL-34s, 6550s or KT88s.