Addressing the 6SN7 craze:
I am getting emails asking about the 6SN7. And I also see that topic on the head-fi forum.
I am sorry but we will not make these. Let me give some explanation why and you can post this on the forum if you like.
Producing tubes is extremely difficult. A layman might think it should be easy to produce such ancient technology nowadays. But it is not. It is unlikely that any new company which does not yet have some production line and knowledge in this area will start making tubes. We have the production capability to make directly heated tubes. Indirectly heated tubes like the 6SN7, EL34, EL84, KT88, 12A*7 types, etc require a very different process and are a different category of tubes. The investment needed to build up a new production line from scratch for these is huge.
The signature sound of our tubes is due to the use of thoriated tungsten filaments in all types. We are the only producer of 300B variants and rectifiers which use such filaments. When I got in contact with the former Elrog company (before I took over) I discussed the idea of a thoriated filament 300B with the previous owner. I always preferred the sound qualities of thoriated tungsten filaments. The difference this makes is not only audible but can also be measured. Thoriated tungsten filament triodes show a more constant amplification factor independent of the signal amplitude. Oxide coated filaments show a slight compression of the amplification factor as the tubes are driven harder. This results in the fast and dynamic sound with high resolution in our tubes. The motivation behind the development the Elrog ER300B was to get this sound character which is usually only obtainable from transmitting type triodes. The goal was to get the sound of an 801A in a tube with 300B characteristics.
Indirectly heated tubes have a cathode which is yet different and cannot be made with the characteristics of thoriated tungsten filaments. Also the above mentioned compression of amplification factor is even more present in indirectly heated tubes.
The mission of my company is to make tubes with the best possible sound quality. This is only obtainable from directly heated tubes which are inherently more linear than indirectly heated tubes. And among the directly heated tubes those with thoriated tungsten filaments are superior.
I hope this helps to understand why I will not go this direction and expand the production to indirectly heated tube types. I am the sole proprietor of the company and wish to stay independent. Getting investors on board to build up such a production would change the company and bring pressure for growth and more profit. And any potential investor would most likely not engage if he analyses the market and risk of not getting any ROI. And if there would be a wealthy audiophile willing to do this without the need for profit, there would be other much more interesting things to develop with directly heated tubes. There are still more ideas how to push the sound envelope further.
So if you want to get more of the Elrog sound signature it makes more sense to get an amp which uses only tube types we produce. And if you like the ER300B sound, maybe check out the tube which it is modelled after. Be it old production 801A types and their variants 10, 10Y, VT25, VT62 or of course the Elrog types which are available as ER801A, ER801A-Mo and TM801A. Of course the amp needs to be designed for the 801A.
Best regards
Thomas