PC-10A board differs from the original Dynaco PC-10 PCB in that it is configured to use either a 6GH8A or 6U8A driver tube in place of the 7199. However, the PC-10A is not just a tube swap with some pin rewiring. Additional components are included to insure stability and low distortion when 6GH8A or 6U8A tubes are employed in place of the 7199. Advantage is easily available Driver tubes and not very expensive like 7199.
The PC-11 PCB is intended as a restoration board, and thus, the circuit configuration, and mounting hole locations, are consistent with the original Dynaco PC-11 circuit
board.
The SCA-35 Capacitor EFB™ Board replaces the original multi section power supply filter capacitors as well as all the associated resistors and high voltage rectifier diodes. Besides larger overall capacitance, additional metalized polypropylene bypass capacitors have also been included. The original cathode bias resistor has been replaced with an innovative Enhanced Fixed Bias feature that allows your SCA-35 to perform to its full potential with both channels driven. Although rated at 17.5W per channel output power, this is really only true if only a single channel is driven. With both channels driven, however, power output is typically closer to 14W per channel (for the original SCA-35), and distortion is significantly higher as well. This is largely due to various compromises related to the use of the simple, but economical, cathode bias system in the original SCA 35 design. Check Tronola.com site