Tube amp question

I have the Black Ice F35 and I tried running it with a matched quad of new KT120 tubes and at around 60-65 watts the amp shut off and went into protection mode.

I talked to a Mr. Michael Allen, who told me it was OK to run the KT120 tubes and to bias them the same as the 6550 tubes, but when I talked to him again to tell him about the amp shutting down with the KT120 tubes he informed me that though the amp will run with KT120 and even KT150 tubes that the 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.

He also stated that future Black Ice amps might possibly be designed from the get go to run the KT120 and KT150 tubes to achieve more power.

So I just removed the KT120 tubes and reinstalled the 6550 tubes and that is what I run currently, but I did buy another matched quad of KT120 tubes and run all 8 in my Primaluna Dialogue Premium HP integrated amp and they sound great and really add more detail to the top and bottom end.

Maybe your results will vary with the Black Ice F22, see for yourself and PM me with your results.

OP, I would ask Mr. Allen to confirm that there will be no damage to his transformers by running the KT150’s...and maybe have him put that in writing. While the amp may supply ’enough’ voltage for the KT150’s to work, as russ69 pointed out above, you will not get all the power that the tube can produce.

Personally, I would be more concerned about using a transformer that was not originally designed for this tube, but if the manufacturer is ok with that..so be it.

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.