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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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Tuesday, February 14, 2017

Integrated SE Amplifier with the 46

Hi!

Here is another single ended amp based on the 46. This time an integrated with input selector and volume control.




It is basically the same circuit as the recently shown 46 power amp.




A DACT stepped attenuator serves as volume control directly after the input selector which in this case only selects between two inputs. One RCA and one XLR. The latter goes through a pair of input transformers before it is routed to the input sect switch.





The parts on the top needed some rearrangement to make room for the input selector and volume control.



Since this the power transformer does not really need a large cover as on the previous amp this helped to free up enough space.




When tested with the volume control at maximum and with a line stage this amp sounds just like the last one. The 46 is absolute musical ecstasy.



Extremely rich tone colours almost to the point of exaggeration. Bass is surprisingly solid and well defined with the right speakers.




Not as much resolution as a thoriated tungsten output tube. But sheer fun to listen to.




This will certainly not be the last 46 amp built be me. Stay tuned!

Best regards


Thomas





Thursday, February 9, 2017

The Ultimate 300B Amplifier - Part 1

Hi!

After the excellent results from the fully differential 300B amp an ultimate version with all silver transformers and plate chokes was the logical next step.




It shares the same circuit and chassis design of the previous one. All relevant transformers and chokes are upgraded to silver.




These are all the silver goodies which go into one channel. Like the copper version the amp will have 4 chassis. Two mono blocks and each with it's separate power supply.




The sub assembly with all signal relevant transformers and chokes, except the input transformer which is directly mounted to the top plate near the input stage:





These mono amps are meant to complement the ultimate phono and line stage for a fully differential system without caps in the signal path. A set of these power amps together with the phono and line will be demoed at the High End fair in Munich this year.

Stay tuned for updates as the amps get completed.

Best regards

Thomas

Wednesday, January 25, 2017

News from the ELROG tube factory 3

Hi!

Time to give some update about whats going on with the ELROG tubes! We had been tremendously busy in the recent months. Many things to take care of. We are working hard to keep up with the demand.





We had been overwhelmed with the interest in the newly announced ER242C. More requests had been received than we plan to make in the first production run. Sorry to all those whom I had to turn down. We will make sure to set up a second production run later this year. The first run will be next month with deliveries expected in March.




We'd like to thank all customers who put their trust in the newly founded Deutsche Elektronenröhren Manufaktur GmbH. We are happy about the tremendously positive feedback received for the tubes delivered from the new company. We are also very proud about the extremely low failure rate. So far there had been zero returns of 300B tubes produced under the new company. There had been very few 211 and 845 fails which were caused by mechanical defects during shipping and which of course got replaced on warranty. So far the total failure rate is a tremendously low 1-2%. Of course 0% would be ideal. But to be realistic, any technical product can fail and the type of failures we saw were caused by shipping and had been immediately apparent upon receipt. We will work hard to keep the quality up.




We are very happy to announce a new distributor for ELROG tubes. Amtrans joined the family and will distribute our tubes exclusively in Japan. LiveAcoustics, our distributor for Singapore will also cover Malaysia and plans to set up a shop there as well. Emmanuel Lebreton, who covers China, Hong Kong and Taiwan has been quite active to promote the tubes in his area and is in the process of setting up his website Baoling Audio. And of course George Lenz of TubesUSA.com continues to distribute the tubes in USA and Canada. All other regions and the European Union are covered by us directly.  Send an email or call if you want to order tubes or if you are interested to become distributor for your country. The elrog.com website will also be set up soon and regularly updated with distributor and order information.






Above a picture to show you some of the faces behind the tubes. George Lenz (left). Matthias Klepper (right) and myself. The photo was taken at the ETF where we also donated a pair of ELROG ER300B for the auction. Anders who auctioned the tubes sent this photo of his amp with the Elrogs installed:






I am getting many questions about new tube developments. Besides the ER242C another new type is in the pipe and we plan to launch it at the High End fair in Munich.






Yes, Deutsche Elektronenröhren Manufaktur GmbH will be exhibiting at the High End fair in Munich. Visit us in room F231e to see and hear the ELROG tubes. In addition ELROG tubes will also play in room F231c in a joint set up with PrimaryControl, Wolf von Langa and VinylSavor.

Looking forward to meet in Munich!

Best regards

Thomas

Sunday, January 22, 2017

Music : Klaus Schulze, Timewind

Hi!

From time to time I go through my record collection and pull out some vinyls which I haven't listened to for a long time.  I recently played a record which I bought as teenager. Timewind by Klaus Schulze.




It is interesting how some of those records which one liked as a kid aged very well and still sound fresh and relevant while others don't.

Schulze's timewind definitely is one of the first category. Klaus Schulze was among the pioneers of electronic music and heavily influenced generations after him. He experimented a lot with synthesisers and sequencers. Timewind was released in 1975 on Brain. My particular copy was pressed in France and distributed by Virgin. This was his 5th record and can be considered as his break through. The first track which gave the album it's name is a mesmerising and pulsating flow of the typical analog synth sounds of the 1970ies which gained a lot of popularity again most notably in the revival of the Moog Modular Synthesizers. These analog sounds are still unmatched by digital instruments.
Klaus Schulze was among the creators of the 'Berlin School' style. Nowadays it would be called Ambient. The name Berlin School was given since most musicians who experimented with this were working in West Berlin during that time.




The surrealistic cover art perfectly matches the music which Schulze dedicated to Richard Wagner. Klaus was active and successful over a long time and gave concerts up to 2010. More information can be found on his website.




If you are into electronic music and don't have this album get the vinyl and savor it!

Best regards

Thomas

Saturday, January 14, 2017

Tube of the Month : The 83

Hi!

Let's start 2017 with a tube presentation. I picked a rectifier for this month, not just an ordinary one but a full wave mercury vapour rectifier: The 83.




As a Full wave rectifier it has two plates and a common cathode. It is meant to be used with a power transformer with a center tap on the secondary.

The 83 is directly heated, which means the filament is identical to the cathode and thus it only needs four pins as shown on the left. The two plates get connected to the high voltage secondary. The center tap of the high voltage secondary severs as ground. Rectified voltage output can be taken from either side of the filament or from a center tap on the filament winding. The filament of the 83 needs 5V and a hefty 3A. The 83 was developed for higher current demands. It can deliver up to 250mA. Besides the increased current handling capability the mercury vapour enables a low voltage drop of only 15V which is mostly constant and not impacted by current draw. This is beneficial in applications with varying current draw as for example in Class AB amplifiers. Maximum peak inverse voltage is 1400V. For all technical parameters see the RCA data sheet. The tube comes in a ST16 size glass bottle which is the same envelope as seen on a 2A3. As far as I am aware the 83 was never made in
globe shape glass, only ST shape. Unlike other mercury vapour tubes like the 866A or 816, the 83 can be mounted vertically as well as horizontally. It also does not need a pre heating of the filaments to vaporise the mercury before high voltage gets applied. But of course it will not hurt to treat it gently. One of the most well known uses of 83 rectifiers was in the TV-7 tube tester. This tube tester is also an example in which the tube is operated while mounted in horizontal position and no means of pre heating are applied. 83s were quite popular with amplifier builders during the 1990ies but seem to went out of fashion. I haven't seen any in an amp since a long time and I never used it myself. That's why I only have a limited stock of tubes to show. But maybe one day a 93 will find it's way on top of one of my amplifiers. Let's start with a 83 made by RCA:







The small droplets of mercury are visible on the inside of the glass:






Here we see the little pouch which contained the mercury during manufacturing of the tube








Almost no getter visible in the tube





When filament voltage is applied without high voltage the mercury evaporates and condenses on the glass:




When high voltage is applied to the plates the ionised mercury gives of a blue glow




And the mercury completely evaporates and re condenses only at the base.





The blue glow is mainly visible inside the plates. It is not a constant glow but it flickers with the mains frequency (50Hz here in Europe). The glow lights up in each plate alternatively which can be seen in this short video clip:





The beating between the frame rate and mains frequency causes a visible flicker. In real life the flicker is too fast for the eye to notice.




Next we have some PhilipsECG JAN83 made for the military.




These were made in the 1980ies. Contrary to the RCA shown above they have a large getter deposit.




In my test set up which I built to show the glow these have a much fainter blue inside the plates:




Measurements showed that they exhibit a larger voltage drop than usual 83s. As with other late tube productions these also seemed to have suffered from poorer quality compared to tubes from the golden era.




Here are my most beautiful 83 tubes.




Made in Italy by Fivre.





Each of them carries a tax sticker




The top of the tube:




Base:




These boxes prove again that the Italians know a thing or two about style:




Nicely sealed boxes:





As in the RCA 83 they have a little pouch which held the mercury:




Close ups:






The Fivre 83 in operation:




The higher the current draw the more intense the blue glow:




Here we see how the mercury condenses mostly at the base, leaving the glass clear.









I hope you enjoyed this first Tube of the Month presentation of 2017!

Best regards

Thomas