{"type_number":"GZ34","canonical_url":"https://tubeofile.com/tubes/GZ34","manufacturer":"Mullard","tube_type_key":"rectifier","tube_type_display_name":"Rectifier","base_name":"Octal","description":"High-vacuum full-wave rectifier with indirectly heated cathode (unipotential). Designed by Mullard/Philips for high-current power supply applications in audio amplifiers and electronic equipment. Notable for low voltage drop and high current capability compared to directly-heated rectifiers of similar ratings.","is_directly_heated":false,"completeness":"high","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."],"references":["https://frank.pocnet.net/sheets/030/g/GZ34.pdf","https://frank.pocnet.net/sheets/035/5/5AR4.pdf","https://frank.pocnet.net/sheets/093/5/5AR4.pdf"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa0013.htm","tdsl":"http://tdsl.duncanamps.com/show.php?des=GZ34","radiomuseum":"https://www.radiomuseum.org/tubes/tube_gz34.html"},"raw_equivalents":["5AR4","U77","CV1377","R52","596","GZ37","U54"],"equivalents":[{"type_number":"GZ37","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"GZ33","reason":"Electrically similar Octal rectifier but different pinout (centre-tapped heater on GZ33) — check circuit compatibility","has_detail_page":true}],"pins":[{"pin_number":"1","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"2","function":"Heater","function_code":"h","notes":null},{"pin_number":"3","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"4","function":"Anode 2 (Plate 2)","function_code":"a2","notes":null},{"pin_number":"5","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"6","function":"Anode 1 (Plate 1)","function_code":"a1","notes":null},{"pin_number":"7","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"8","function":"Heater / Cathode","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"5.0","numeric_value":"5","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"1.9","numeric_value":"1.9","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Rectifier","tube_type_key":"rectifier","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"550","numeric_value":"550","unit":"V","param_group":"absolute_max"},{"key":"PIV","display_name":"Peak Inverse Voltage","value":"1500","numeric_value":"1500","unit":"V","param_group":"rectifier"},{"key":"Vdrop","display_name":"Voltage Drop (typical)","value":"17","numeric_value":"17","unit":"V","param_group":"rectifier"},{"key":"C_max","display_name":"Max C-input Filter Capacitor","value":"60","numeric_value":"60","unit":"µF","param_group":"rectifier"},{"key":"Ia_peak","display_name":"Peak Anode Current (surge)","value":"750","numeric_value":"750","unit":"mA","param_group":"rectifier"},{"key":"Idc_max","display_name":"Max DC Output Current (total, not per-anode)","value":"250","numeric_value":"250","unit":"mA","param_group":"rectifier"},{"key":"Rs_min","display_name":"Min Series Resistance (C-input)","value":"75","numeric_value":"75","unit":"Ω","param_group":"rectifier"},{"key":"ri","display_name":"Internal Resistance","value":"50","numeric_value":"50","unit":"Ω","param_group":"rectifier"}]}],"synced_at":"2026-04-08T07:56:15.210Z"}