Tube amp question

@falconquest

If I may, three different scenarios to share. The first two are friend’s amps I helped them with when they were ready to make tube changes. The last mono block amp(s) mentioned are mine.

1. The Jolida amp my friend Alan had KT150s in it, worked fine, sounded neutral, lacked the velvety rich sound. Swapped to PSVANE KT88s. More engaging now. My friend loves it, everything he was looking for from the sound in this circuit.

2. The Black Ice F22 my friend Richard has came new with lower grade EL34s. He swapped in new production Genelex Gold Lyon KT77s. He truly enjoys the change and sound after there was 50-70hrs on the 77s. He listens to it daily now. I don’t think he’ll ever try KT150s after hearing this setup.

3. My own tube mono block amps have massive transformers, came stock with KT150s, sound very linear, super clear, neutral, amazing sound stage and detail. The designer recommends running them as low as 40ma and high as 60ma. I run them at 50ma per tube. Sometimes I’ve felt it was lacking velvet tube sound, kinda missed KT88s. Can’t run 88s in my amps, too high of plate voltage. Split the difference with KT120s, a more lush tone. After the KT120s had 100hrs on them, I have no desire to put the KT150s back in immediately. KT120s were as close as I could get back to 88 sound. Been enjoying them past three months. 

Your F22:

fwiw, I’ve heard your F22 amp and it can sound really nice moving from EL34s to KT77 or KT88s. Hey, KT150s are expensive. FYI, my four KT150s are sitting nicely tucked away in their boxes. Bigger is not always better, IMO. You can also try extra nice KT77s or KT88s s in the F22 if you want to stay closer to a rich full sound without being overly neutral. Trying to save you from skipping a good in-between option to consider. Some of my other friends rotate from 150s back to 88s, 77s - often.

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. :)