Is there a way to improve the transient response of tube guitar amps that have tube rectifiers?
Yes, you can do this mod to any tube amp, regardless of the type of rectifier. You need to add a 1N4007 diode in series with the V+ line coming off the second filter cap, feeding the splitter and preamp. The cathode (BAR) should face the preamp circuitry, and the anode is connected to the junction of the choke output and second filter cap. When the output tubes pull current from the main supply, the power supply sags. The diode turns off during this sag and isolates the splitter and preamp supply nodes from the reduced main supply. For a short sag, the preamp voltage does not change at all, but continuous heavy loading will eventually pull these voltages down too.
