Today it is exactly three years since I announced the founding of Deutsche Elektronenröhren Manufaktur GmbH and the continuation of the manufacturing of ELROG tubes after the former ELROG GmbH Elektronenröhren & Co KG went bankrupt.
A lot has happened in those 3 years. Not only did we completely redesign every tube type to increase reliability and sound quality, we also developed new tube types.
The ER845 and ER211 were the first 2 types made by the former ELROG GmbH, which was joined by the ER300B in 2014. The most notable changes were done to those two, by inverting the structure to raise the heat generating plate higher up in the bulb as done in other 845 and 211 tubes. This eliminated heat problems in amplifiers with poor air ventilation around the tubes.
The ER300B was joined by two other UX4 based directly heated triodes, the ER50 and ER801A, the latter not only meant as replacement for the original types 801, 801A and VT62 but also the 10Y and VT25. The ER300B got completely overhauled with a more ruggedised filament and new plate structure. The thoriated tungsten filament was kept as this is the main reason for the sound qualities of our ER300B which is highly regarded as among the very best on the market and preferred by many over any oxide filament type.
And of course we also decided to make rectifiers in form of the ER274B and ER274A. These rectifiers surpass other 274B and 274A types with higher voltage rating. Many of our customers replace a 5U4 with the ER274B and it can also work in applications designed for the 5R4.
The ER284 and ER242 are premium variants of the 845 and 211 and are electrically compatible with those. They use molybdenum plates instead of graphite.
The latest addition are the ER887 and ER888. These are new tube types which do not have old production equivalents. These are driver tubes specifically designed to provide the large grid voltage swing to drive 845 output tubes in the best possible manner and in a 2 stage amplifier. Both types are electrically identical. The ER888 uses a molybdenum plate while the ER887 has a graphite plate. With these we now have a total of 11 tube types in the portfolio. Development will not end here and more new types will follow.
I would like to thank our customers and the entire tubephile community for the continuous support and encouragement. And of course a big thank you to the hard working staff at Deutsche Elektronenröhren Manufaktur GmbH, producer of ELROG vacuum tubes made in Germany.