Have you checked the DC voltage at the grid of the output tube to ensure your bias with the VT231 is correct? Proper bidding makes a positive...
I chose a different LED than the one specified in the BH thread. I used a HLMP-KB45-A0000 which is only 30 mcd versus 9600 mcd for the...
The harmonic distortion measurement might give some indication of warmth. Tubes tend to have strong second order distortion which is typically...
Separate names with a comma.