Electrically similar Octal rectifier but different pinout (centre-tapped heater on GZ33) — check circuit compatibility
Electrical Specifications
Absolute Maximum
Anode Voltage (max)AC Voltage per Plate (max RMS)550V
Rectifier
Peak Inverse VoltagePeak Inverse Voltage1,500V
Voltage Drop (typical)Voltage Drop (at 225 mA DC)17V
Max C-input Filter CapacitorMax C-input Filter Capacitor60µF
Notes
Indirectly heated (unipotential cathode) — provides controlled warm-up and reduced stress on filter capacitors compared to directly-heated rectifiers like 5U4G.
Capacitor-input filter requires minimum total series resistance (Rt) per plate that varies with AC input voltage: 75 Ω at 2×300 V, 125 Ω at 2×400 V, 175 Ω at 2×500 V, 200 Ω at 2×550 V. Rt includes transformer secondary winding resistance.
Maximum DC output current depends on filter type and AC input voltage. Capacitor-input: 250 mA at 2×300 V, 250 mA at 2×400 V, 200 mA at 2×500 V, 160 mA at 2×550 V. Choke-input: up to 250 mA at 2×550 V.
Very low voltage drop (~17 V at 225 mA) compared to directly-heated rectifiers like 5U4G (~44 V) or 5R4 (~67 V). This means less 'sag' under load, which some guitar amplifier designers consider less desirable for clean-channel feel.
Pin 8 serves as both heater and cathode connection — the cathode is tied internally to one side of the heater.
Pin Layout — Octal
1No Connection
2Heater
3No Connection
4
Socket-Compatible Tubes ⚠ Not electrically compatible