HIFISTATEMENT | netmagazine - Portrait of the ELROG Elektronenröhren GmbH and an interview with Dr. Klaus Schaffernicht

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Portrait of the ELROG Elektronenröhren GmbH and an interview with Dr. Klaus Schaffernicht

20.01.2014 // Jürgen Saile

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The photo shows the assembled triode system. The M-shaped wire is the cathode. The four springs at the upper end provide contact to the getter. At the top the ring can be seen which holds the getter material before it is flashed after evacuation. On the right side the plate which is milled from a block of graphite

The 211 is a directly heated transmitting triode. It's advantage is a very good linearity. The thoriated tungsten filaments need a much higher operating temperature than oxide coated filaments. The 211 requires very high plate voltages exceeding 1000V. The filament needs 10V at 3.25A which is not an easy task to provide since it needs to be very clean for best sound. Ideally the filaments are heated from a DC source. AC is possible but results in residual hum due to the high filament voltage. The tube also needs a capable driver with low output impedance which can provide 150V peak to peak. Otherwise the sound would be dominated by the non sufficient driver tube and not by the output tube. All in all not recommended for beginners in DIY.

The tubes are built by hand. Each tube has a unique serial number which is engraved on a small plate inside the glass.

Final quality control is done by Dr. Schaffernicht personally. Each tube is burned in for 25 hours. Source: Thomas Mayer

During burn in the tubes are operated at high currents. This is done to drive residual gases out of the plate and other electrodes which then get caught by the getter. Source: Thomas Mayer

DREI H Vertriebs GmbH (Chord ULTIMA PRE3)