I converted this movie theater/PA amp into a guitar amp. Dual GZ34 rectified with four cathode biased KT66s. All octal preamps running on a DC filament supply.
Input 1 uses a 6SN7 cascode input followed by a defeat-able single knob tone control and volume with a pull-boost feature. The following stage is a 6SF5 anode follower. Input 2 is Marshall-y with a couple 6SL7 stages. After the inputs are mixed, a 6SN7 dc-coupled cathode follower drives the tone stack. The amp also has a global negative feedback loop.
