With the envelope prepared, the next ingredient required is the glass base which forms the junction between outer chassis and the three basic metal elements that make up the heart of a triode. The next craftsman on our tour thus would be the base master. With a large and a small flame, he constructs the tube base and inserts the four wires that will make the connections. Airtight precision and correct spacing are keywords for his work. It is amazing again to observe what a skilled artisan can achieve with the correct mixture of sand, potash and boron oxide thrown together with some secret ingredients and heat.

The female touch and accuracy are needed next to assemble the tube's metal innards from strips of a secret nickel-based alloy in the metal shop into the 32-piece cathode of the KR 842. The other parts of the tube innards are crafted here as well.

All this work is done with fine tools, magnifying glasses and even a microscope. The metal parts become attached to the glass base and four wires. Then the base is molten to the envelope while an opening remains in the base to connect the glass envelope to the Tesla vacuum pump. We have to proceed to the other side of the factory to see this while we pass various signs on doors warning of high voltage or gases.

We also meet KR Audio's tube master who worked with Ricardo and now works with Marek to combine all their latest ideas into actual manufacturable tubes. He knows not only all the can-and-can't-dos of producing vacuum tubes but, because he has worked in this factory all of his life, every single machine involved in the process beginning to end.

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 842s have been sucked dry of air and are ready to be detached and activated. With the pump literally molten to the tube, it is the glass master's job to detach the tube from the machine with great care and a sharp little flame without breaking the vacuum.