Hi everyone!
I've been reading this forum for a while and finally decided to register and create my first topic. I would love to get some feedback from you, please be honest I can take the hit.
I finished my DIY amplifier project a while ago but wanted to get some feedback from people who know their stuff. I always wanted to design a tube amplifier but didn't have much time for it. This project took me about 6 months to finish. It has two power amplifiers inside: a solid state one based on STA540 and a class-A single-ended 6SN7+6V6 tube stereo amplifier. You can switch between 2 amplifiers using a knob on the front panel.
The reason of having 2 amplifiers is simple: the device is used as a computer audio amplifier. Most of the time I use it to watch videos or playing games. STA540 is a high-quality power amplifier and it will be more than enough for these purposes. But when you want to enjoy some music (e.g jazz) you can simply turn on the tube amp. Such system can significantly extend tube life.
I wanted to use a modern circuitry in the tube amp design. The operating point (cathode currents etc) is precisely controlled by the integrated circuits, while the audio signal only goes through the tubes and high-quality capacitors and resistors. I also used a switch mode power supply which is much smaller and more efficient than classic linear ones. In addition to that, it doesn't have this 50 Hz hum, as the operating frequency is higher than 100 kHz. I know that sometimes it can produce a high-frequency noise, so I used a comprehensive filtering of the output voltages. There is a "magic eye" tube (6E5C) on the front panel for indication, but it's just a nice looking gimmick :). I ordered PCBs in China and it took around 10 days for them to get delivered to my place.
And finally, a very important thing: the amp's appearance! I used brushed aluminium and jarrah wood as the main materials. The CNC routing was done here, in Australia. I gradually sanded the wood (the last sandpaper was 400 grit) and covered it with 4 layers of transparent lacquer to enhance the natural colour and to protect the wood. I also added copper pipes for steampunk appearance :). The labels on the rear panel were laser engraved.
Overall, I'm very happy with this amp and I'm glad that I found some time to finish it. Both amps sound great. I prefer to use the tube one to listen jazz or blues while the solid state one is better (IMHO) for more bassy genres.
I'm thinking about making more of these, potentially customised and set up a little startup. Do you think it's worth a try?
