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.

Tube Type DC mA PIV FIL AMPS Max ACV DCV DCV DROP
Diode Rectifier 425
5AR4 / GZ-34 25015001.945041510
5V4-GA 1751400237540025
GZ37 35010002.845038837
5U4-GA 2501550345038144
5U4-G 2251550345038144
5U4-GB 2751550345037550
5Y3-G/GA 1251400235036560
5R4GYB 2503100290036263
5R4G/GY/GYA 2503100275035867