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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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Sunday, April 19, 2015

45 / 2A3 Mono Amplifiers

Hi!

Here is a set of just finished Mono Blocks which can be used either with 45 or 2A3 as output tube. The driver is also selectable between 10Y and 45.




The amps share the same circuit and transformers as a previous set of similar amps. Just a different amplifier chassis layout as used in my most recent builds.




The wood is smoked eucalyptus which is a very dark brown, almost black. All transformer covers and oil capacitors are varnished in a graphite grey metallic tone.




The two amplifier chassis with 45 in the driver tube sockets:




Interstage and output transformers are Tango of which I still have some stock. The input transformer is the silver version of Lundahl LL7903 which I use in most of my all DHT amplifiers.





The power supply chassis:




Top view:




The amplifier chassis:




Top view:




These amplifiers reminded me again what a great tube the 45 is.




It simply is the queen of tone. Those who are blessed with efficient speakers should give this tube a listen. Especially in globe fashion.




I already described the sound of the different tube combinations here. So I won't go into that again.






The amp with a 10Y in the driver socket:




Besides the 10Y, a 801A can be used as driver as well.

2A3 as output tube:




45s are still available as NOS or good used tubes, despite many claims that the supply dries up. This tube has been produced in large quantities over decades and is still easy to find. Also in my experience they last quite long if run conservatively. The situation with 2A3 is a bit different. Bi-plate versions can be found rather easy, but the mono plates got very expensive and scarce.

So no excuse not to consider such an amp if speakers with a matching sensitivity are available.

Best regards

Thomas


Tuesday, April 14, 2015

VinylSavor at the Munich High End Fair 2015

Hi!

Time flies! The next High End show opens in a month in Munich, May 14 - 17. I will exhibit again with the same partners as last year, Wolf von Langa and PrimaryControl.






We will exhibit in the same room as last year: F231c / Atrium 4.

There will be different 300B amplifiers on demo using the Elrog ER300B tubes. Preamplifiers will be an updated version of the 10Y line stage and the latest LCR phono with EC8020 tubes.






See you in Munich!

Thomas

Thursday, April 9, 2015

Tube of the Month : The E55L (revisited)

Hi!

Since I used the E55L in a headphone amp recently, this is a good opportunity to have a closer look at the tube again. The first tube of the month post about the E55L did not show any photos of the internals, so it is time to revisit it.




Technical details of the tube have already been covered in the first post. So this one will just show photos.

Philips Miniwatt E55L:




Amperex:




Another Amperex:




Telefunken:




Mullard:




For closer inspection of the internals I picked the Amperex with green letters. A close up before it is getting destroyed:




The glass removed:





Peeking into the side opening of the pate already gives an idea of the fine structures of the grids:




The top with the getter ring:




Side view:




A close up showing the pins going through the glass:




The plate removed from the system:





This leaves the remaining assembly exposed, cathode, control and screen grids and beam forming plate:




A close up to the rod which holds the screen grid:





The heater wire inside the cathode:




Heater wire partially pulled out:




Close up:





The heater:




Cathode and control grid:




The control grid wires are extremely fine and barely visible:




A human hair in comparison:




A close up shows what a marvellous piece of engineering the control grid structure is:




Cathode and control grid separated:




More views of the grid:







And lastly a few photos of glowing EL55s:









Best regards

Thomas