Having guarantee issues with KR Audio?

Sounds like KR definitely has some quality control issues. I had two KR 845 tubes go bad in my Art Audio Carissa Signature, I was lucky that Joe covered them as he had mentioned he likely wouldn't be covered by KR. I have TJ Fullmusic 845's installed for over two years without a problem.

I love my Frankensteins. It is the most dynamic 300b amp I have ever heard.I wouldn't sell them for what I paid.I had Kr balloons and one failed as well(aprox 175 hrs.). I've since moved to fullmusic carbon plates and the amps are singing,even better than with the Kr's IMO.

Regarding 300b compatibility with Frankenstein - at least Mesh plate 300B from Sophia Electric does not work. I have purchased them after KR failure and listen to no more then one hour. Strong distortion so I was afraid of failure. Confirmed by Sophia Electric that tubes are not suitable in my amplifier. I sold tubes and they work very well in typical 300b amp.

I also purchased Emission Labs 320B-XLS - no problems and borrowed Full Music mesh for a few hour. Owner of Full Music noticed that anode shines too much and was affraid of failure.

Regarding the sound of Frenkeinstein - maybe I try another 300b - but at the moment I think this amp is for 300b enthusiast, not for me. Experienced 300b audiophiles told me, that limitations I hear are "generic" 300b feature and every 300b SET they heard more or less suffers of slow and "exaggerated" bas not managed to keep the rhythm - and some high frequencies roll-offs. Speaker compatibility is not an issue as I own Coincident Total Victory 3 (great speakers, I like them very much)

"generic" 300b feature and every 300b SET they heard more or less suffers of slow and "exaggerated" bas not managed to keep the rhythm - and some high frequencies roll-offs.

Sounds like any poorly designed tube amp to me, certainly not a characteristic of a properly executed 300B amp, nor the tube itself !

If you want to try what I believe to the best current production 300B tube currently available by a long mile (and I have tried most in my SOTA silver foil output transformers amp)...Check out the EAT 300B, a truly remarkable sounding and super reliable tube IMHE...

I purchased a quantity of matched pairs and have a NIB pair listed in the AudioAsylum classifieds at waaay below retail price.

I had very poor experiences with KR. I had an older KR Enterprise amp that kept burning through 842 VHD tubes (I think that was the name). The tubes died a number of times and I had to replace with no recourse from KR. The amps sound nice, but it's clear that KR wants nothing to do with customers who have issues with their tubes.

I believe their new amps are better designed than the older KR Enterprise stuff.