Having guarantee issues with KR Audio?

I love the Frankensteins. They just flat out please both the audiofool and music lover in me. These tubes were recommended (and sold to me) by Israel Blume himself, and he hasn't steered me wrong as of yet. I can't believe he would make an error and then not rectify the situation, so I have to assume that KR Audio has issues.
Funny though, I'm at 150 hours or so.

After speaking with Eunice Kron( owner of KR) over dinner in Las Vegas, she advised that KR no longer has any intention of selling KR 300Bs to any outside source, instead opting to manufacture tubes solely for use in their own amplifiers. However, right after this conversation, she doubled the price of the 300B tubes over night.

As for reliability and warranty of KR 300Bs, their longevity for those tubes manufactured in the last 18 months has deteriorated. They seem to be more prone to premature demise. Coincident has received back about a half dozen 300Bs that have gone bad within 6 months of use. KR does offer a 6 month warranty. Well this is not really a warranty at all, as it turns out. After sending back to KR all the defective 300Bs, KR denied offering replacements because " the tubes were misused by their owners and therefore not subject to the warranty". In other words, KR offers a warranty but if a tube becomes defective it is the user's fault and not KR's.

In the case of 2 customers who had their KR 300B balloons expire within 2 months of use, we replaced them free of charge inspite of the fact that we only offer a 14 day warranty on tubes.

Due to all of the above, we no longer stock nor sell KR 300Bs. Our standard supplied EH Gold Grids have proven to be extremely reliable( not a single failure in the field) and sound superb. For those who wish to upgrade, we highly recommend the Sophia or TJ carbon plates. They sound great and their manufacturers extend a genuine up to one year replacement warranty. We no longer offer for sale, any 300Bs other than the EHs since we are confident in their reliability and sonic performance.

As for using differing 300B tubes in the Frankenstein amplifiers, all of them will work as the operating voltages and bias current of our amps is within spec for all of them. Stereomojo used the Frankenstein as the reference amplifiers in a 6 tube 300B comparison with no tube failures. If the 300B is properly manufactured and falls within the specs required for a 300B, it will work without incident in the Frankenstein amplifiers. Some tubes are better constructed then others and will last longer but that is a tube issue nothing to do with the amplifiers.

Israel Blume
Coincident Speaker Technology

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)