Now the total parts kit of Nutube headphone amplifier is prepared as above picture. Here I would explain some adjustment point for completion.
I put 2.0 mm pitch 17 pin connector but this connector is quite tight and a bit hard to insert all pin of Nutube (in addition, pins are very soft). After inserting before power-on, please confirm all pin connection by tester.
A barrel connector for AC adaptor connection is prepared on board. BUT general AC adaptor generates lots of HAM noise. If you cannot prepare high-quality 9V power supply, please use 006P (9V) battery as power supply. Battery driven state is quite good from viewpoint of noise.
One caution is,,,, A silk on board says "12V centre +" but adding 12V will break 3.3 V regulator (NJM2884), which maximum input is 10V. Please never add more than 10 V as a power supply.
Again I can say, 006P is the best (or 6-seriesed AA or AAA). I recommend battery drive.
After completion, please prepare your favourite music and add to the amp, also prepare headphone. In the initial power-on, you may be surprised unusual noise but this amplifier requires adjustment because it is "fragile" vacuum tube circuit. Adjust right and left grid voltage by wiper and set them for the best sound state. You may notice Nutube will have some light. It seems, both brightness are the same, R and L channel will be balanced.
Once proper grid voltages are set, you don't need any adjustment except for volume control. Enjoy Nutube amplifier!!!
(As noticed, I will sell this kit just for 4-unit. Preparation for 4-unit costs a lots (more than $200 just for four Nutube), and I cannot prepare more than one because I need to avoid financial loss in the worse case, no one will order....!!)