{"type_number":"12E1","canonical_url":"https://tubeofile.com/tubes/12E1","manufacturer":"Mazda","tube_type_key":"beam_tetrode","tube_type_display_name":"Beam Tetrode","base_name":"Octal","description":"Beam tetrode, indirectly heated, designed for use as a series or shunt control valve in stabilised power supplies. Also used as an audio output tube in triode-strapped configuration.","is_directly_heated":false,"completeness":"medium","notes":["Anode connects to a top cap (American miniature type), not to a base pin. Requires a top-cap clip lead or adapter.","Originally designed as a voltage regulator series-pass tube for stabilised power supplies, intended for parallel operation of multiple tubes. The datasheet typical operating conditions (Va=Vg2=150V, Ia=200mA) reflect regulator service, not audio use.","Screen grid is limited to 300V maximum — considerably lower than many audio beam tetrodes. In audio circuits, B+ voltages must be chosen carefully to avoid exceeding this rating, especially in cathode-biased designs where screen voltage can rise.","Triode-strapped mu is only 5.5, requiring significant drive voltage. At higher anode voltages (above 300V) the plate curves compress severely and bias voltage becomes very large, making the tube impractical above ~300V in triode mode.","A ruggedised variant, the 12E1R, was also produced.","The 12E1C is listed as an improved successor variant."],"references":["https://frank.pocnet.net/sheets/196/1/12E1.pdf","https://tdsl.duncanamps.com/show.php?des=12E1","http://vinylsavor.blogspot.com/2022/10/tube-of-month-12e1.html"],"source_urls":{"r_type":"https://www.r-type.org/exhib/abn0133.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=12E1","radiomuseum":"https://www.radiomuseum.org/tubes/tube_12e1.html"},"raw_equivalents":["CV345","CV8025","5B/351D","VX6044"],"equivalents":[],"similar":[{"type_number":"S11E12","reason":"Indirectly heated regulator beam tetrode with near-identical operating characteristics (gm 14 vs 13.5 mA/V, Pa_max 35 vs 28W), but S11E12 has anode on base pin 3 (IO socket) rather than top cap — not pin-compatible without rewiring.","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":"Screen Grid","function_code":"g2","notes":null},{"pin_number":"5","function":"Control Grid","function_code":"g1","notes":null},{"pin_number":"6","function":"No Connection","function_code":"nc","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Cathode","function_code":"k","notes":null},{"pin_number":"TC","function":"Anode (Top Cap)","function_code":"a","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"6.3","numeric_value":"6.3","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"1.6","numeric_value":"1.6","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Beam Tetrode","tube_type_key":"beam_tetrode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"800","numeric_value":"800","unit":"V","param_group":"absolute_max"},{"key":"Vs_max","display_name":"Screen Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"35","numeric_value":"35","unit":"W","param_group":"absolute_max"},{"key":"Ps_max","display_name":"Screen Dissipation (max)","value":"5","numeric_value":"5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"300","numeric_value":"300","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"150","numeric_value":"150","unit":"V","param_group":"typical_operating"},{"key":"Vs","display_name":"Screen Voltage (typical)","value":"150","numeric_value":"150","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-10","numeric_value":"-10","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"200","numeric_value":"200","unit":"mA","param_group":"typical_operating"},{"key":"mAs","display_name":"Screen Current","value":"10","numeric_value":"10","unit":"mA","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"14","numeric_value":"14","unit":"mA/V","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.3","numeric_value":"1.3","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"23","numeric_value":"23","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"8.5","numeric_value":"8.5","unit":"pF","param_group":"capacitances"},{"key":null,"display_name":"Maximum Control Grid Voltage","value":"-100","numeric_value":"-100","unit":"V","param_group":null},{"key":null,"display_name":"Maximum Voltage between g1 and g2","value":"400","numeric_value":"400","unit":"V","param_group":null}]},{"section_number":2,"section_label":"Triode Strapped","tube_type_key":"power_triode","specs":[{"key":"Va_max","display_name":"Anode Voltage (max)","value":"300","numeric_value":"300","unit":"V","param_group":"absolute_max"},{"key":"Pa_max","display_name":"Anode Dissipation (max)","value":"37","numeric_value":"37","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"300","numeric_value":"300","unit":"mA","param_group":"absolute_max"},{"key":"ra","display_name":"Anode Resistance","value":"600","numeric_value":"600","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"9.5","numeric_value":"9.5","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"5.5","numeric_value":"5.5","unit":"—","param_group":"typical_operating"}]}],"synced_at":"2026-04-23T00:37:21.660Z"}