Tube amp question

Just a little more background here. The amp came with the EH EL34's. Having read a lot about the Genelex Gold Lions, I decided to give them a try (same EL34's). The sound quality was improved and I really liked them but they seemed to lack a bit of dynamics that I'm looking for. I am driving a pair of Legacy Audio Signature III's which are 4 ohm and 93db sensitivity. I'm looking for a bit more kick from them that I know they can provide.I purchased a quad set of KT120's and after allowing them to warm up, 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. I emailed the factory and they believed that I must have a bad tube. This happened just after the Russian invasion of Ukraine and the run on tubes. I could not locate another set of KT120's anywhere. As I researched more I stumbled across a guy who had four remaining KT150's that are actually ARC matched. I am waiting for those to arrive. It will be interesting to see if the amp reacts the same or how it will perform. This damned Russia thing happened right in the middle of my experiment. But I don't at all want to devolve the conversation into politics. I appreciate everyone's insight

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.