DISCLAIMER: Vacuum tube circuits work with dangerously high voltages. Do not attempt to build circuits presented on this site if you do not have the required experience and skills to work with such voltages. I assume no responsibility whatsoever for any damage caused by the usage of my circuits.

All rights of photos and text reserved. Usage of photos or text from my blog on other websites or for any other purpose only with prior permission. If you want to use any material from my blog please contact me by email.

Tuesday, November 8, 2016

News from the ELROG tube factory 2


Here another update from the tube factory. Last month was busy with some renovation of the work places ongoing. Now tube production is in full swing.

Above the new packaging for the 300B tubes which just arrived. The packaging reflects the change on the company while it retains the Elrog as brand name for the tubes.

There are also some changes made to the tubes themselves. We are now using new bases which are custom made for us by Reinhöfer Electronic:

These are beautifully made with massive pins which provide more stability. We also did some changes to the glass bulbs. While in the past the top of the glass was shaped in house by hand, we now get these done by a professional glass blower for laboratory glass ware:

While the glass itself remains the same special glass made in Germany by Schott, we now deliver the raw glass tubes to Schmidt Laborglasgeräte where they receive the final shape. This gives a more uniform look from tube to tube. However for those who prefer the traditional hand made look, we are still also doing these. With these changes each part of the tubes and each manufacturing step is entirely done in Germany.

Here a peek into the factory floor, showing the vacuum pump stands:

Assembled 300B tubes waiting to be put on the vacuum pump:

The tubes on the pump:

I am planning a series of posts 'Making of a vacuum tube' which will show each step in detail. Here a brief preview what will be shown in upcoming posts:

Here we see Olena preparing filament assemblies for 300Bs. Also captured on video:

Tiny 50 micron thick thoriated tungsten wire:

Which gets spot welded into the filament assembly frame:

Here we see a close up of an assembled 300B on the vacuum pump ready to get outgassed:

Each plate carries the initials of the person who assembled it. In this case it was made by Olena. The internals get heated up by RF induction through the coil. This drives gasses out. During the entire process the tube is exhausted:

The plate glows bright red during this step.

The surface of the plate turns to the characteristic grey :

I hope you enjoyed this glimpse into the tube factory. Stay tuned for more detailed posts about the making of a vacuum tube!

Here we see a matched pair in it's packaging with the measurement protocol. Each pair gets selected to within less than one mA in two op points. We now typically reach extremely low grid currents in the range 30-40 nano Ampere!

Inquiries about the Elrog tubes have been tremendous. November production is already pre ordered. If you are interested in 300B, 211 or 845 tubes, please pre order soon since we expect December production to be sold out quite quickly as well.

Here a quote from a customer who received his ER300B tubes recently:

I recieved my Elrog 300b's today. My amp, Alieno, revealed the shocking truth to me of how extreemly good thes tubes really are. I have been using the Takatzuki 300B's ( a great tube ) but this was something else. All the desireable parameters that we lace our conversations with in the highend eg.space,air,timberal accuracy,speed,tonal balance etc etc became manifest in the expression of this tube.....simply amazing. Congratulations!

Best regards



  1. Looks like ELROG and the new company are doing very well! It is good to see that you didn't stop with R&D and just carry on with the usual business, you actually improved upon an already remarkable design. Now, what's next? Maybe a "new" model for the lineup, the 10Y or a 45...? So many great tubes to choose from! ;-)

    1. Thanks,
      New types and variants are in the works. We are planning some exciting new stuff for next year...

  2. Guten Morgen Thomas, 2 Fragen:
    Was kosten die Elrog 300B und wo gibt es diese Tassen???
    Übrigens, sehr interessante Einblicke...
    Viele Grüße, Peter

    1. Hallo Peter,
      Das Paar ER300B kostet in D 1050 Euro. Die Tassen gibt es natürlich nur bei uns. Mehr zu Preisen auch hier:

  3. Danke für die Info!
    ...und die Tassen? :)

    1. Kriegst Du gratis dazu wenn Du bald Röhren bestellst. Es sind noch einige wenige Tassen da. Aber ich werde neue machen lassen. Bitte bei der Bestellung angeben, dass Du gerne eine Tasse haben möchtest

  4. A free cup with every euro 1.000 order! :-)

    1. Yes :-)
      At least for the next 10 orders....

  5. W-Th, not a NOS? Worlds 1st these days.