Knoppson Williamson Amplifier, KWA-91D
Power Tubes: JJ-Electronic KT88
Amplifying Tubes: Russian NOS 6H8C (~6SN7)
Feeddback (BF+1): 14dB
Input Sensitivity: 1,5V/1MOhm
Maximum Power Output: 2X20W
Nominal Speaker Impedance: 6Ohm (4-8Ohm feasable)
While the amplifier is most suited for 6Ohm speakers,
these amps work for 4-8 Ohms too due to special OPT
transformers (moving into Class AB region at high levels)
The amplifier is a plug-n-play for KT66, EL34, 6L6GC and 6550
This is my fourth attempt in building a commersial Williamson Amplifier. I have made as many as 10 of these
four of which wounded up as pure coated pine versions while the rest had to be painted due to storing flaws.
These amplifiers incorporate a minimum of feedback while keeping the output levels for each channel the same
as the tubes ages. A slight feedback is also good for the damping factor. But in my opinion more feedback than
14dB is not neccesary.