This project shows a tube amplifier with the tube 20B from Emission Labs (EML), the rectifier tube 5Z3 is also from this manufacturer. The circuit is inspired by suggestions that I found on the Emission Labs page - combined with some changes that mainly affect the power supply. If you pay attention to the quality of the (very few) components, you can build a device that plays on a very high level.

For the DC heating voltage power supply (EML20B) and the anode voltage power supply I have designed printed circuit boards, which I also use in other projects. The device has a switch-on delay, which suppresses the inrush current of the toroidal transformer, the regulated heating voltage is applied immediately after switching and the anode voltage (CLC-filtered) will switch on after 45sec (adjustable). In addition, I have placed the few components around the 20B on a specially developed circuit board, which I have milled with my rapid prototyping system. The transformer and the output transformer (Lundahl) are housed in the wooden cylinder on the top of the device. The wood elements are made of clear finished multiplex, the aluminum plates are black powder coated. I put special attention on the fact that from the outside screws are invisible, only on the back and on the bottom could not be avoided ... but I can live with that :)

The output power is specified by the manufacturer with a maximum of 8 watts. To operate with my EMS-12EXB that is much more than sufficient!

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