Here's the schematic for the guts of a TS-808 or TS-9/TS-9R (click on the image to enlarge). This circuit omits the footswitch and its circuit and it omits the Half-Supply resistor divider. The nodes marked Vhs are connected to half-supply or 4.5V here. NOTE: The only difference in the TS-808 and TS-9 is in the output buffer circuit. These include two resistors in the output, R1 and R2 here.
MOD NOTES:
- The conversion to TS-808 involves swapping out the above resistors
- The TS-808 and original TS-9's used a JRC4885 Op-Amp - this needs to be changed out if it is not the same type to get back to TS-808/TS-9 reference
- The Distortion Mod involves switching in 3 diodes in series into one of the diode-feedback branches, resulting in asymmetric clipping and a brighter, more British sound
- The Bass Boost (aka Brown Sound) is done by modifying the 0.047uF capacitor on the inverting input which sets the low frequency rolloff of the distortion stage
- The Level Bypass shorts across the output (level) control giving a full-out setting. By using a second footswitch, this make a Solo-Boost footswitch - or allows two different output volume settings, footswitchable.
