Knoppson Guitar Amplifier, KGA-92B
Data [drawings]:
Rectifying Tube: EZ81 (Full-Wave Rectifier)
Input Amplifying Tube: EF86 (AF Pentode)
Phase Splitting Tube: ECC83 (Twin AF Triode)
Output Push-Pull Power Tube: EL84 (Power Pentode)
Input Resistance: 10k
Amplifier Options: Solid State/Electronic Tubes
Volume Option: None
Distorsion Option: Combined Volume and Distorsion Knob
Filter Options: High-Pass (400Hz) and Low-Pass (4,2kHz)
Output Power: 3W@Tubes, 8W@SS
This Guitar Amplifier incorporates two very different amplifiers, one is a solid state (SS) amplifier which I
have designed by myself, it is in fact a Power OP. The other amplifier is the core of KGA and thus a tube
amplifier which is not fully my own design but a design by John Schroeder. I have however not copied the
hole design, all biasing and my favorite Edison Bias is my own design. After careful consideration I
incorporated a series connection of two 9V batteries to enable a power output to be of real use. The
batteries thus supplies the KTA only and not the tube part of KGA, which by the way would be quite
impossible with regard to battery lifetime and Class A operation. I have also incorporated a very special
kind of distorsion adjust feature. The potentiometer actually regulates the voltage supplied to the
output push-pull tubes thus making it possible to set distorsion to a certain level which is conserved
for all volume settings with the same knob.
