A visit to KR Audio in Prague
In an hour and a half, Skyteam member CSA flies us direct from Amsterdam’s airport to Prague’s Ruzyne airport in the Czech Republic. On board, we get excellent service and have our first encounter with the Czech language and the Bohemia Sek [bubbly]. Eunice Kron of KR Audio warned us ahead of time that it’s never advisable to pick up a taxi at the airport. Either proceed instead to a special desk at the airport and let them get you a ticket for a taxi or have one already waiting for you. We arranged for a taxi via the hotel we would be staying at.
With only carry-on luggage, we got through customs smoothly and found our driver in the arrival hall. He took us to his car a few meters further on, a shining Skoda Octavia stickered with ‘It happens at the Hilton’. A little kamikaze drive through the outskirts of Prague and along the river Vltava/Moldau later and we arrive at our hotel.
We were booked into the executive floor and registered. Whenever you visit Prague and have outgrown the backpacker stage, the Hilton’s your place to stay. It’s been completely redecorated after the severe flooding of 2002 and is one of the few hotels with an atrium sans safety nets. Jumpers are welcome but why would you?
From our room, we have a partial view of the river and up the hills where the Prague television tower dominates the skyline. The restaurant of the hotel serves a perfect late-night dinner and we sample some more Bohemia Sekt. Service here is still spelled with a capital S.
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Next morning we take on of the waiting Skodas of the hotel –- it appears the Hilton has its own fleet of squeaky-clean cars – the car takes us to the KR factory. We leave the center and drive through other city outskirts. Large housing projects in communist style; gray prefab concrete. It takes about 20 minutes and then we turn right and stop at Nademlejnska number 600. We find the concierge and try to make him clear in our best Czech that we are to visit KR. He makes a call and shows us how to get to KR.
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We enter the building through a courtyard and ascent the terrazzo stairs to the second floor. The entrance reminds of an old school. Wide stairs leading up and down. The atmosphere is filled with a combination of the smell of bleach and industrial gasses. At the top of the stairs we meet Eunice Kron. After a warm welcome she leads us to her office. It is a warm day and Eunice’s office is even warmer. Our hostess has some things to finish and takes us along to a room stacked with familiar KR designs and parts. With pride Eunice points us the latest KR Audio product, the integrated KR VT 340. It is a combination of the P150 pre-amp and the Antares VT320. The amplifier is now in its final test phase before shipping to Holland. Holland? Yes, distributor Eurogram is the first in the world to receive the amp. And now at the moment we are writing this, we are playing this amplifier in absolute awe. Soon the world premiere of a review will appear on 6moons!
Also new, but very much less exciting is a metal cage to cover the 1610 tubes of the Kronzilla amps. Some idiot government agent wants to save the precious baby hands when they touch the glowing tubes. Now the Kronzilla monster has to be caged.
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It this point Marek Gencev enters the room and we meet. Marek is the young apprentice Ricardo Kron took on to first assist him with his work and later when it was clear Ricardo’s time in this world was ending, to succeed him.
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After great US coffee me meet with Eunice’s right hand Buba. Buba is not only the Jill of All Trades, she also is fluent in Italian. Eunice, a born New Yorker, studied and lived for a long time in Italy and only ten years ago she moved with Ricardo to the Czech Republic. Now Eunice and Buba communicate in lively Italian and Buba translates (some of it) to the craftsmen and craftswomen in Czech.
It is funny to be in a working environment where everybody calls each other Mister or Misses. It is like being thrown back in time, and maybe that is really the case.
Eunice shows us around the factory and follow the process of making a tube. In this case a KR 842 triode. The factory is split in basically two regions. One that handles all gasses and flames and the other all things electrical. In the middle a section of assembly and carbonizing is located.
Although the building is squarely built around a courtyard, the hallway where the rooms are adjacent seems to be more or less running in a circle. It is very large and typically built for lots of workers. Now, and especially because the day we visit is the last day before summer holidays, it is dead quiet.
Originally Dutch company Philips used the building as their tube manufacturing plant used. With the communist occupation of 1948, the factory was nationalized and under the name of Tesla the factory was used to make tubes for the Russian occupator. Tubes are not susceptible to nuclear radiation so the products were very much in demand with Moscow in those days. With the fall of communism the factory came again in private hands of Alessa Vaic. Some art in the hallways still remind of the communist Tesla days.
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Rain or shine, the craftsmen and craftswomen are still at work in the old factory. We start our tour with the master glass man. It is he and his fellow glass men that convert long pipes of SIMAX, a very hard Pyrex-like, glass into tube envelopes. For an 842 he starts with a length of glass and measures the needed length, carving a scratch on the glass. Then he uses a red-glowing wire to cut the glass.
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The cut length is enough for two 842 and using a mark the glass master heats this spot until the glass is just soft enough to be extruded into a cone. He then separates the two coned glass tubes. A felt piston with a hollow tube is now entered in the 842 to-be. With amazing skills the glass master transforms the cone shaped top of the tube in a smooth round surface as we know from all tubes. A combination of twirling, other wrist movements and blowing in the little tube is part of this process. Back in our schooldays once a year a glass artist showed up to educate us and sell some of his doggies and other glass creatures. Compared to what we see here in Prague that was absolute peanuts.
Prague is a real city of glass. Great artist stem from here and everywhere there is something made of glass in a great artistic way. The Hilton is clad in glass and in front of it an artistic expression of stainless steel and glass adds to the feeling of the city.
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Now the envelope is ready the glass base is needed. This base will form the junction between the chassis and the three basic metal elements that form the heart of a triode. The base master is the next craftsman we visit. With a large and a small flame he constructs the glass base of the tube and inserts the four wires that will make the connections. Air tightness and correct spacing are keywords for his work. It is again amazing to see what someone can do with the correct mixture of sand, potash and boron oxide together with some secret ingredients and heat.
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The female touch and accuracy is needed to assemble the metal innards of a tube. In the metal shop strips of a secret titanium based alloy are cut and prepared.
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Then fine female hands convert the strips into the 32-piece cathode of the KR 842. Also the other parts of the tubes innards are crafted here.
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All this work is done using fine tools, magnifying glasses and even a microscope. The metal parts are attached to the glass base and the four wires. Then the base is molten to the envelope. There is still an opening in the base of the assembled tube. This opening is used to connect the glass envelope to the Tesla vacuum pump. We have to go to the other side of the factory to see this.
On our way we see various warning signs on doors. High voltage or gasses.
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We also meet the tube master of KR Audio. This man worked with Ricardo and works now with Marek to get all the ideas they have realized into a tube. He knows all the possibilities and impossibilities of producing vacuum tubes. Not only that, but because he works all his life in this factory, he knows all the machines available.
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In the vacuum room we find a whole collection of Tesla branded equipment. Various test benches and vacuum tools. On the big vacuum pump a series of KR 842 have been sucked vacuum and are ready to be detached and activated. The pump is molten to the tube and it is the glass master’s job to detach the tube from the machine without breaking the vacuum. With great care and a sharp little flame he detached tube by tube.
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Again, this job can only be done after years of experience. Other tube factories use machines to do the job. Here accompanied by a Tesla rectified radio all is done by hand.
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The next stage is to activate the getter. This process captivates all spurious gasses still lasting in the tube. And this the only time you will see a KR glowing.
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The final stage before testing is the attaching of the ceramic base with the pins. When this is done, 128 hours have been spent on one single tube. Now we get an idea why the price asked for a tube is what it is.
The proof of the pudding is in the eating, so after the factory tour we go to Ricardo’s listening room in the factory. A sunny, and now quit warm room filled with nantique radios and related paintings and posters. At the end of the room on a rack there are a few examples of KR equipment and a simple Sony CD player. Of course a Kronzilla is present here. Loudspeakers are amongst a few others the large Silverline Audio Grandeur 4-ways. We listen while having some more coffee to a few discs Ricardo appreciated and talk some more with Eunice about the past and the future.
Although the past looks dark and the loss of Ricardo is not easy to come by, the future looks bright. Marek is full of new ideas for tubes and amplifiers and the market is getting better. Eunice is proud to tell us that Nagra signed KR up for use in their amplifiers. The reason is the constant build quality of the tubes and the sound quality. More negotiations with other companies are on their way.
We leave Nademlejnska full of impressions and make an extra tour through the city. The Cow Parade is in town and everywhere colorful herbivores show up. It is a pity we have to leave soon. Prague is an intriguing city with many contradictions that make it worthwhile to go back sometime.
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Now we have a little piece of Prague playing and we like it.