DISCLAIMER

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.

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Sunday, August 28, 2016

Tube of the Month : The 30

Here is another small directly heated triode which probably deserves more attention than it gets. The 30:




The 30 was intended as detector or amplifier tube in portable radio receivers. It is a battery tube like the 31 which was the tube of the month in January.

It has the same UX4 base and pinout as the 31 and also the same size bottle, ST-12. Being intended for battery powered equipment it's oxide coated filament was designed to operate at as little power as possible. The filament voltage is only 2V and needs a measly 60mA to operate! That's only 120 milliwatts of filament power. The 30 is typically operated at 135V plate voltage (180V max) and at around 3mA bias current. It has a plate resistance of 10k Ohms which makes it still usable with an interstage or line out transformer if they have enough primary inductance. It is more easily usable with LC or RC coupling. The amplification factor is 9.3. I never used the 30 myself. It could be an ideal companion for the 31 in a nifty flea power SET amp to drive ultra efficient speakers, or as tweeter amp in active set ups, or maybe a nice little all DHT headphone amp. The plate curves show the typical excellent linearity of directly heated triodes:




Which look just as nice in real life:




Since I never used the 30 in any project, I do not have a lot of samples. It was made in globe shape as well as ST shape. Unfortunately I have no globe 30s which were named UX-230. But I do have some rather nice ST shaped tubes. Let's start with the most beautiful ones. Sylvania VT-67, a variant of the 30 made for the military.




These have beautiful white ceramic bases.




Some close up shots:







The base with leaf-logo:




The top:




The plate:





There had been two military variants of the 30 with different VT-numbers. Initially it was introduced as VT-27:




The VT-27 had a black phenolic base which was upgraded to low loss bases for the VT-67. The latter could be micanol or ceramic. Here a micanol base:




A phenolic base:




The base above is from a tube made by Tung-Sol:





The top:



Side view:




Another VT-27 made by Sylvania:




Top:




Side view:




Hytron type 30 / VT-67:





Another angle:




Side view:




Top:





And of course the 30 was also made by RCA:








And as last example a 30 from National Union:





A beautiful little tube with excellent linearity.

Best regards

Thomas

Sunday, August 7, 2016

The Future of ELROG Tubes

Hi!

It has been a bit quiet about Elrog during the recent months and I would like to give an update about the state of the company and the future. I have some bad and some good news. The bad news is that due to various reasons Elrog struggled financially and was forced to enter the insolvency process. The good news is that Elrog tubes will continue to be produced. I founded a new company which acquired all assets and machines of Elrog. This company will continue the manufacturing and distribution of Elrog branded tubes.




The name of the company is Deutsche Elektronenröhren Manufaktur GmbH. This translates to German Electron Tube Manufactory Ltd. The name of the company was chosen to represent the heritage and tradition of Elrog GmbH & Co Elektronenröhren KG. The bright yellow glow of thoriated tungsten filaments was selected as the company colour.

I am very happy to announce that two key people committed to come on board of the new company. Without those it would be impossible to continue the production. Matthias Klepper who was managing production and development at Elrog, will be the Chief Technology Officer of the new company. He will continue to overlook production and new tube development. I got to know Matthias very well during the recent months. He brings a vast knowledge and experience in different fields. He especially impressed me with his deep understanding of vacuum tube technology and production as well as his electronics expertise especially in audio amplification. Vacuum tubes require know how in electronics, physics and chemistry all of which Matthias masters in an impressive way. In addition to that I also found a close friend in him who shares my passion for music and audio technology. 

And I am very happy that Dr. Schaffernicht, the founder of Elrog, also committed to be part of the new operation in an advisory role. He brings in his vast experience in tube manufacturing which spans all the way back to the Telefunken era. The Elrog tubes are his life achievement which we will continue to carry into the future. This is both a great honour and a great responsibility.

300B, 211 and 845 tubes will be continued to be produced at the same premises in the city of Hagenow on the same equipment. During last week the production line has been refurbished. Production will be resumed in the coming week. The tubes will continue to carry the ELROG name.




Originally I planned to announce this news at the end of this month. But since I keep getting inquiries I decided to share this earlier. Especially since the elrog.com website is currently down and the Elrog email address is not reachable in the moment. It will take some days or even more than a week until the website is released and transferred to the new company. Until then please contact me under the VinylSavor address which can be found in the link Impressum / Contact on the upper left of this site. There is also a phone number. Please use this contact information for any inquiries or questions until the elrog.com site is accessible again.

Any emails sent to info (at) elrog (dot) com during the last week have not been read. Also access to the emails had been intermittent before that time. In case you sent a message to that address and did not get a reply, please contact me and I will follow up.

Please note that Deutsche Elektronenröhren Manufaktur GmbH is not the legal successor of Elrog GmbH & Co Elektronenröhren KG. We cannot assume any liabilities of the old company. Nevertheless we will do our best to resolve any open issues or warranty claims in an amicable way.

In case you are sending inquiries please allow for some time to respond since there is a lot of work in the beginning. All emails will be answered. We are also starting to take preorders. New tubes will be available in September. Some limited stock of tubes is already available now for serving urgent needs. It is expected that demand might be higher than production capacity throughout the rest of the year. One of the top priorities will be to resume production at the highest possible quality level rather than maximum output.

Inquiries from distributors and resellers are welcome. Please contact me if you are interested to represent The Elrog brand in your area and we will discuss details.

These are exciting times and I am hoping for your support to re-launch the brand and continue vacuum tube manufacturing in Germany. I would like to thank all the loyal customers of Elrog and would be happy to continue to serve you with german made vacuum tubes.

Best regards

Thomas

Tuesday, August 2, 2016

The Ultimate Phono Stage - Part 2

Hi!

Assembly of the all silver, fully balanced EC8020 LCR phono stage is complete.




The only part missing is the wooden frame, face plate and back plate with the connections. These will be added after initial testing.




Dark maroon red metallic transformer covers complement the gold coloured top plate nicely.




The array of 8 EC8020 triodes is always an impressive sight.






The power supply is finished as well:




The transformer cover will be added at the end after testing and fine adjustment of voltages.




Part 3 with the completed phono stage and some initial sound impressions will have to wait a bit due to some travelling. Please be patient and stay tuned.

Best regards

Thomas

Tuesday, July 26, 2016

D3a Differential Phono Preamplifier, Part 3

Hi!

In this last post about the fully differential phonostage with D3a tubes, I am sharing some more photos, also with the unit glowing in the dark and some assessment of it's sound.




Here a photo of the phono with the power supply:




As mentioned it shares pretty much the same circuit and parts quality with the differential EC8020 phono.




The D3a tubes glowing away:






8 D3a tubes playing in unison.





So the big question: How does it sound?




This unit shares the same strengths with the EC8020 version. The absence of capacitors in the gain stages shows it's advantage by removing the last bit of grain from the sound and giving extremely revealing timbre and details.




The result is surprisingly close to the EC8020 version. So the sound descriptions given for that one are mostly valid.




The EC8020 gives a tad more resolution, ambience and decay of tones. It is for those who only accept the best of the best.




The D3a however is a close runner up at significantly less tube costs. Let's see how the ultimate version with all silver transformers and plate chokes will do. Stay tuned!

Best regards

Thomas