ECL805 push pull integrated amplifier

Here I show you my most recent build, a compact 12 watts per channel stereo push pull amplifier which features 3 line inputs for direct connection of a line source. Full power when a typical USB DAC is connected can be obtained with the volume knob set to the 1 o'clock position.

It operates in ultra linear mode without any feedback. The tubes are grid biased and adjusted to 27mA for each tube separately. When tubes are swapped, the amp needs to be adjusted again. This can be done on the inside, terminals for measurements are provided and adjustment is done with a potentiometer for each tube. The schematic I did design myself, it is a straightforward design which is kept simple and safe, nothing fancy but it performs very well.
The power transformer is custom made for this little amplifier.
It uses a cathodyne phase inverter and a sensitive driver. Heaters are grounded using a voltage divider from the B+, which is 280V.
The ECL805 (6GV8) is very robust and capable tube which is surprisingly suited for audio: sensitive triode section and small pentode which lets current flow at lower voltages with a slightly higher power rating compared to the one inside an ECL82, I love it.