This is a chart showing the specifications for 5 volt rectifier tubes that can be used in guitar amps. By having this information on a chart you can choose a rectifier tube that will best suit your playing style. The more of a voltage drop (DCV Drop) you have the more sag or compression you will have. The starting volatge is 425 volts from a diode rectifier and each tube’s specs drop from there. Also shown is the current available (DC mA) from the rectifier and the filament current draw (Fil Amps). It is important to pay attention to the filament current draw. Your power transformer may not have enough current supply on the 5 volt winding for the rectifier tube. All specifications were taken from the General Electric Essential Characteristcs book. Your actual voltages may vary.