SET EL84 tube amp DIY project

category: 

se el84 tube amp

A Decware EL84 Zen Amp clone

Making a low power single ended amplifier has always been in my designing plans. Obviously such a construction requires the appropriate speakers, particularly horn type designs, so that the output of the amp can reach an efficiency satisfying level.
Once at a certain point, I came across the designs of the Decware SE EL84 Zen amp, which had quite good reviews among the tube amps DIY and Single Ended tube amp builders.

se-el84-1
This simple and clever design was exactly what i had in mind. The most convenient way to develop my idea was to use an already existing design.

Tube amp diy

Chassis are made of wood, and i build the whole construction in an aluminum plate (3mm thick). All parts are mounted on the aluminum plate. Finally i coated the aluminum plate with plexiglass (acrylic sheet colored dark gold)
I ordered the output transformers in a local workshop, (Greece / Thessaloniki). All tube sockets are porcelain, and all the critical paths wired using silver-teflon cables. I also used metal film resistors, and WIMA capacitors.

se-el84-3

The whole circuit is very simple. It is a common cathode design with the 6922 tube driving the power stage with el84. I changed only the two cathode resistors (150Ω /8 watt) with heavy duty type for heating resistance. In the Power supply I used the 5U tube for rectifier according to Decware manual.
You can find EL84 and svetlana SV84 tube data in tube data pages.

el84-schematic

How it sounds this tube amp ?

(back in 2002...)
This simple EL84 tube amp meet his first "crash test" when we put it in the same rack with the GRAAF GM20. We connected it with George's Valmas Coherence II Jeff Rowland pre amp, and we used George's Amati Homage loudspeakers.
Clear voices incredible solo's unbelievable mid and high - frequencies ! absolute separation and purity not expected! But .... we needed POWER !

If you have horn loudspeakers in your living room then its time to build this EL84 tube amp... "monster" because ... sound does matters !

costas sarris

acknowledgements :

  • Decware Zen EL84 Amp
  • George Valmas for his effort

Tags: