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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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Thursday, December 31, 2015

Happy New Year!

Hi!

It is Sylvester and time again to recap what was going on during 2015 and what is planned for 2016.






2015 was the best year for VinylSavor so far. Many exciting projects and some significant improvements in sound quality.






First there was the new generation of LCR phono stages with a new improved biasing scheme introduced in a EC8020 phono stage and later also used in new builds of D3a phono stages in both landscape and portrait chassis styles.






The 211 had a significant come back for me with 4 newly build amplifiers. A new incarnation of the 6HS5/211 amps, two new versions of the 801A/211 concept with Tango transformers. Both in square chassis, one of them with less height and more floorspace and the other introducing the new tower style chassis.





While the former were commissioned by a customer, I built the tower style version as demo amps which I plan to show at next years High End fair. And then there were the totally over the top 211/211 amps with all silver transformers.






Silver was a big topic this year, even more than 2014. Besides the silver 211/211 amps there were the all silver 300B amps with power supplies using mercury vapour tubes. Those two amps represent the best sounding power amplifiers I have built so far.




On the preamp side there was also another build of the single ended 10Y line stage with silver finemet OPTVCs.





And then there was the silver version of the differential line stage. This project was the biggest surprise for me in 2015 and held the biggest step in sound quality I achieved in a component so far. It deserves the title 'ultimate line preamplifier'. A special thanks to those who commissioned these over the top projects and helped to push the envelope!






Although the 10Y and especially it's specially selected variant 1602 remain my favourite line stage tube, there are other interesting candidates as well. For example the 26 as used in a 26 line stage built this year. There was an interesting project going on this year about which I have not written anything yet. This involved building a test setup which enabled the use of a whole variety of different tubes in a line stage and culminated in the build of two new preamps. The tale of these two preamps will be told in 2016. Thanks a lot to the originator of this project which enabled new insights into different sound worlds.





So what is planned for 2016? The ultimate line preamplifier definitely needs a companion phono stage. I finally need to proceed with the all differential EC8020 phono which I already mentioned in last years Sylvester post.  Initially as a copper version and hopefully there will also be a chance to build it all silver in similar fashion to the ultimate line preamp.





The topic of push pull power amps is also not forgotten yet and maybe 2016 will be the time for a VinylSavor PP amp.




And finally I decided to look into digital playback. Although vinyl will remain my preferred source, I understand that there are a lot of people who simply prefer the convenience of digital and the possibility of downloading music. And finally not everything is available on vinyl.





All the best for 2016 for all of you and your families!

Thomas

Monday, December 28, 2015

Music : Freddy Quinn, Auf hoher See

Hi!

At events like the ETF or the High End fair I occasionally like to play some fun records. It is interesting to watch the reactions. While some seem to take things too serious, others really enjoy them. This is one of those records. 'Auf hoher See' by Freddy Quinn.






Freddy Quinn was very popular in Germany during the 50ies and 60ies and produced a lot of records during that time and also played in some movies.

Most of his songs are about the sea and sailors. This is also the theme of this record as is evident from the title and cover. The album was released in 1962 on Polydor. Like most of the Polydor albums of this era, the recording quality is exceptional. Also the vinyl quality of these early Polydor discs leaves nothing to wish for. They can be recognised by the orange label with the stars at the top. Later releases have a red label and are of lesser quality but still mostly very good. The first song on the album is probably the best and also the one which often leaves people with their mouths open if they haven't heard such a record before. It starts with water waves which almost give the feeling as if the water is splashing over your feet. Then a choir slowly sets in which is unbelievably realistic. And finally Freddy starts to sing. His particular accent and the way he rolls the 'rrrrr' together with the hilarious lyrics is really funny. Freddy Quinn probably didn't take himself too serious when he recorded this.





And this is how to listen to such a record. Don't expect anything serious or artistically challenging. Just have fun listening to it and be amazed by the truly exceptional recording quality.

Best regards

Thomas

Saturday, December 19, 2015

Tube of the Month : The EC8010

Hi!

During the last half year or so, all tubes which got presented in this series had been quite old developments from the 1920ies to 1930ies. So I decided to pick a more modern one for the last Tube of the Month post in 2015. A small high frequency triode, developed in the 1960ies by Telefunken. Meet the EC8010.





Readers of my blog are aware of my fondness for the EC8020, which got covered twice already as Tube of the month. The EC8010 is the small sister of the EC8020 and was most likely developed first.


Both tubes share the same 9 pin noval base and pinout. They have similar amplification factors. The EC8010 is a bit higher with 60 vs the 55 of the EC8020. The big difference is in the transconductance which is about double in the EC8020. Still the EC8010 comes with an impressive gm of 28mS. Due to that the EC8010 is often referred to as 'half a EC8020'. In fact a EC8020 could be emulated by using two EC8010 in parallel. Maximum plate dissipation is about 4W which is again half of the EC8020s. In terms of dimensions, the EC8010 has about half the diameter  at about the same height. Due to the extreme scarcity of the EC8020 using two EC8010s could indeed be an approach if the transconductance of the former is needed.
The EC8010 is much easier to find at lower prices. Two of them would only need more heater current than a single EC8020. For all technical details of the tube see the Telefunken data sheet. I never compared two EC8010s in parallel to a EC8020 in an actual circuit so can't comment about any degradation in sound with such an approach. If paralleling is attempted the tubes should be carefully matched. Such high transconductance tubes often vary a lot from sample to sample. And in case of the EC8010 the data sheet gives the amplification factor as 'about 60'. While in the EC8020 data sheet it is listed as '= 55'. This was certainly done for a reason and I would expect some variation in amplification factor between tubes. Since I have more stock of EC8020s than EC8010, I never was tempted to use the EC8010 as substitute and also do not have enough samples to verify considerable differences between samples. I have one same which differs from the others a bit. More about that below. Let's first have a look at the plate curves:




A nice set of curves with good linearity for such a high transconductance tube. Here the measurement of a tube on the curve tracer:





Here two sets of plate curves of the two tubes from my stock which differ the most between each other. As can bee seen there is not only a difference in transconductance but also in the amplification factor:




As far as I am aware, EC8010s were made by Telefunken, Siemens and Valvo. I have also seen some with the National brand name which is owned By Richardson Electronics. Not sure if they manufactured these themselves or rebranded them. Interestingly those National tubes carried both tube designations, EC8010 and EC8020. From the physical appearance and measurements however they had been EC8010. In the 1970ies and 1980ies it was common practice to sell one tube with several designations of types which are similar. However in this case this was going a bit too far.
The EC8010 also has an american 4 digit designation, 8556.




Above some Siemens EC8010 tubes in the characteristic blue/orange packaging.




Close up to the tube:






The boxes:




A few more photos of the Siemens tube:







Valvo EC8010:







Some close ups:






Siemens and Valvo in comparison. Very similar construction with only subtle differences:






The EC8010 has a very unique construction characteristic which I have not seen in any other tube. While the cathode and grid assembly is usually completely surrounded by the plate, only one side of the cathode and grid face the plate in this tube:





A close up shows the fine grid wires:




Unfortunately I don't have any Telefubnken EC8010 to show. So let's proceed with detail photos of the internals. For this I cracked open a dead tube:




Removing the glass envelope gives a much better view to the internals:





Here we can see the cathode and grid which are facing towards the top into empty space:





A close up to the grid:




The top showing the ring which held the getter material before flashing:




Some more views:




The silver cage like structure around the outside was probably only there for mechanical stabilisation.




A view from the side opposite to the grid, with cooling fins of the plate:





Another view to the grid and close up:







The top mica disc and getter holder removed:




Cathode extending out of the second mica disc:






Removing the heater wire:






Removing the outer 'cage' gives yet a better view to the cathode grid and plate:




This is taken from the side so that the gap between grid and plate is nicely visible.




Shot from the grid side:






Here the entire plate structure is nicely visible:






Grid and cathode detached from the rest:




Close up:






The plate:



For size comparison with a finger in the picture:




Close up:




Some more views of the grid and cathode:






Some photos with a match for size comparison:










What a marvellous piece of engineering! Now some photos of a tube in operation.




As expected the entire cathode can be seen from one side.







Close up with the grid wires visible:





I hope you enjoyed this last Tube of the Month post for 2015. Stay tuned for more tubes to be shown in 2016!

Best regards

Thomas