It is a Single-Ended tube amplifier 2xEL84 + ECC83 in aluminum and steel housing.

First step is etching and tin-plating the PCB made in thermal transfer method. Then the system need to be soldered. 1% metallized resistors were sued in this project.

The main assumption of the housing was that it should be as small as possible. Sides were made of 50mm aluminum flat bar and combined with aluminum brackets and rivets. Cut long (1m) flat bar for walls and make holes in them, then prepare brackets mounting up and down. After making mounting holes, rivet them to the sides. Then add pieces of brackets mounting the front and rear wall. After that, rivet all pieces together. The housing should be stable and symmetric. Base can be cut of 1mm steel sheet.

After that, it is time to place the components. The PCB of amplifier should be placed on appropriate supports, so the tubes could be the most exposed to the outside. Make another PCB of power supply – rectifier, filtering electrolytes and power resistors, additionally anode voltage delayed switching system, so high voltage is not applied to the cold anode, but after about 20 seconds of glow. The whole power supply is screwed from the bottom using four M3 screws. There is also a 100W 250V/6.3V flooded toroid, special for audio applications.

At the end, you need to make a „cover” for your device. It should be also cut of a 1mm steel sheet. You can polish, then it would look better. When you make holes for tubes and cables, glue speakers transformers. To cover them, you can use cans (for example tea cans). It looks like that:

The amplifier is switched by turning the volume regulator potentiometer. The second potentiometer is used for regulation of feedback depth – it slightly changes the nature of bass. Switch on the back is used for switching between pentode/tride tubes of the power amplifier.

Final effect:

Link to original thread - Wzmacniacz lampowy SE 2xEL84 + ECC83 v2 by DaKKi