Briefly, mostly photos (reloaded in good quality). I must say right away that there was little experience and knowledge in radio engineering, I made many mistakes. Not being a fanatical lover of warm tube sound, the assembly process itself was interesting to me.
The hardest part is finding the output transformers. I bought myself TU-100Ms, which were already ready from the amplifier (I did not choose for a long time, I took which ones). The frame was made from an aluminum profile and overdid it a bit in strength. The upper part of the body made of 3mm steel. The holes for the transformers and lamps were laser cut. The bottom was also cut out of 2mm steel with ventilation holes: The front panel is made of a piece of aluminum:
The terminal amplifier is assembled in a push-pull circuit on two G-807 lamps. The preamplifier contains two amplification stages assembled on a 6N9C double triode (foreign analog 6SL7).
Advantages of 6Н9С:
1) The lamp was originally designed for sound use;
2) Two triodes in a cylinder;
3) High linearity;
4) Widespread, low price.
1) High internal resistance.
The terminal amplifier (an intermediate link between single-cycle and push-pull amplifiers) is assembled according to a phase-inverse circuit using a 6Н9С double triode, the main purpose is to form two mutually antiphase signals of equal amplitude in the input signal. In the TU-100M circuit, the lamp amplifies the input signal and the voltage amplified by it enters the lamp grid of the first arm of the push-pull amplifier.
Part of the output voltage of the first lamp of the phase-inverting amplifier is supplied to the input of the second lamp of this amplifier. The voltage amplified by the second lamp of the phase-inverted amplifier is supplied to the lamp grid of the second arm of the push-pull
amplifier. Thus, for the first arm of a push-pull amplifier, the signal passes through one lamp, and for the second through two.
It would be better if the voltage supplied to the input of the first arm is equal to the voltage to the input of the second arm. Made a slightly different circuit, with a modified phase-inverse cascade.
Trial scheme: Advantages: 1) Reduced requirements for filtering the supply voltage; 2) Extremely low noise level; 3) Equal output voltage of the shoulders. I found one more option on the forums: 6N9C lamp socket: A DAC with USB connectivity is assembled in the amplifier housing: Setup option: Transformer screens, first sketches on paper: Cut out of 2mm steel: After file adjustment and grinding: A few more photos : I cleaned a little:
Price: unreasonably expensive.
It’s easier to buy ready for 4-5 thousand rubles. But if anyone needs it, I can throw off the files for cutting and for printed circuit boards.