KR Audio Releases HP (High Performance) series of Tubes, only available in the United States.
“KR Audio is the world leader in the production of high performance power tubes and high-end audio equipment.

Located in the heart of Europe in Czech Republic, all products are hand-crafted, starting from the selection of the glass. The high vacuum machines and the choice of the artisan work in both metal, glass blowing and design, chemical and electrical designs plus the absolute refusal to use an automatic line to make tubes is THE reason for KR unique high quality.”

KR Audio are well known as a manufacturer of current production tubes. Some of these are used as stock tubes by manufactures such as Woo Audio (Headphone Amp’s), Lampizator etc. 
One of the companies that regularly does shows with KR Audio are JPS Labs, who introduced some years ago what many rated as the definitive High End Headphone – The Abyss AB-1266 (more on that to come). 
Joe Skubinski is the owner of JPS Labs and he gave me the following background information.
“We exhibited with KR Audio last year in Munich, Germany at the High End show, and got to talking to Eunice Kron, President of KR Audio. What always lured me to KR was their Kronzilla amps with those T1610 tubes, freaking awesome!
Anywho, I suggested that us headphone guys needed some good tubes and I think we could find a market for them in the states, so we purchased some 300B’s and 274B’s to try out on the Woo amps. They were good, however, being a cable designer gave me unique insight into the sound of materials and metallurgy, and I heard areas that could be improved upon. Eunice put me in touch with their lead designer and we began sharing emails about what changes were possible, and worked through a few prototypes to the final design. So.. you could say these new tubes were designed specifically for what we consider to be the highest resolution audio playback available, the Abyss AB-1266 headphones.

Late last year The Evolution of Sound, the North American distribution arm of JPS Labs, received the first shipment of KR Audio High Performance (HP) tubes made specifically to the new specifications, available only in the US market. They sound great, just as you describe them. Bass impact is outstanding for a tube, as if they have a lower output impedance than most, and yes clear as a bell due to their very black background, lack of noise.”
Joe Skubinski

Listening Impressions:
I arranged to buy 3 sets of the tubes.
Matched pairs of the KR HP 300B Balloon, KR HP 274B and KR HP 2A3’s. I set these up in my Woo 234 Mono Reference Amp’s and set about burning them in. To date I have put nearly 500 hours on the 300B’s and the 274B’s. The driver tubes are a matched pair of Tung Sol Round Plate 6SN7 with oval Mica’s, these are carefully chosen circa 1942 production. 
I found them excellent sounding, they have very good detail, bass performance and the clarity is outstanding with very low noise. I actually started with the KR HP 300B Balloon and a Takatsuki 274B Rectifier however the same day I swapped out to the matching KR HP 274B and found them to be a superior match.

I have owned KR 300B Ballon’s tubes previously and going back over them in my memory there is no comparison with these new KR HP tubes. On close inspection the build quality is excellent and superior to the earlier KR Tubes that I have experienced. The bases have been changed to a white ceramic base with gold pins. The KR HP 274B’s are smaller actually slimmer in size, than the traditional Western Electric 274B or Takatsuki 274B. 
I found that burn in took about 400+ hours for them to completely settle down and for the sound to become consistent. I have noticed that it is usually a sign of good things to come when burn in takes that little bit longer than may be found in lesser new production tubes.
I urge anyone considering a tube upgrade or looking for new production tubes to give them a go. They come with a warranty period of six months.
Pricing is for matched pairs:
KR Audio 300B Balloon HP – $1,449 USD
KR Audio 2A3 HP – $995 USD
KR Audio 274B HP – $1295 USD
For further information, specifications etc please go to
Simon Kern – Mono and Stereo Senior Headphone Contributing Writer