{"type_number":"12AU7","canonical_url":"https://tubeofile.com/tubes/12AU7","manufacturer":null,"tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Noval","description":"Medium-mu twin triode. Two independent identical triode sections with individual cathode connections in Noval (B9A) miniature envelope. Widely used as phase inverter, driver, line stage, and combined oscillator-mixer in audio and television equipment.","is_directly_heated":false,"completeness":"high","notes":["One of the most widely used dual triodes, introduced in 1946. The 12AU7 family is the workhorse medium-mu type for audio phase inverters, cathode followers, and line stages.","The 5814A is the industrial/military premium version with controlled characteristics and tighter tolerances.","The 6189/12AU7WA is the ruggedized military version per MIL-HDBK-213A.","The E82CC (Telefunken/Siemens) and ECC802S (Tesla) are special-quality long-life European equivalents.","Can be operated with 6.3V or 12.6V heater supply using the pin 9 center tap.","Max grid resistor drops to 0.25 MΩ for fixed-bias operation (vs 2.2 MΩ for cathode bias).","At Va=100V, Vg=0V operating point: Ia=11.8mA, ra=6500Ω, gm=3.1mA/V, mu=20 — useful for low-voltage designs."],"references":["https://frank.pocnet.net/sheets/127/1/12AU7.pdf","https://tdsl.duncanamps.com/show.php?des=12AU7"],"source_urls":{"r_type":"https://www.radiomuseum.org/tubes/tube_12au7.html","tdsl":"https://tdsl.duncanamps.com/show.php?des=12AU7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_12au7.html"},"raw_equivalents":["ECC82","12AU7A","12AU7WA","B329","CV491","CV4003","CV10323","CV10666","CV8155","CV8221","M8136","5814","5814A","5963","6067","6189","6680","7489","7730","E2163","E82CC","B749","6AU7","ECC802S"],"equivalents":[{"type_number":"6AU7","equivalence_type":"direct","notes":null},{"type_number":"ECC802S","equivalence_type":"direct","notes":null},{"type_number":"ECC82","equivalence_type":"direct","notes":null}],"similar":[{"type_number":"12AT7","reason":"Same Noval dual triode pinout but higher mu (mu=60); lower plate current, higher ra — commonly used as phase inverter","has_detail_page":true},{"type_number":"12AX7","reason":"Same Noval dual triode pinout but high-mu (mu=100); much lower plate current, used as voltage amplifier","has_detail_page":true},{"type_number":"12AY7","reason":"Same Noval dual triode pinout, medium-mu (mu=44); popular in early Fender guitar amp preamps","has_detail_page":true},{"type_number":"5751","reason":"Same Noval dual triode pinout, medium-mu (mu=70); military grade, sometimes used as lower-gain 12AX7 substitute","has_detail_page":true},{"type_number":"6SN7","reason":"Medium-mu dual triode (mu=20) but Octal base; similar electrical characteristics, widely used in audio","has_detail_page":true}],"pins":[{"pin_number":"1","function":"Anode 2 (Triode section 2)","function_code":"a2","notes":null},{"pin_number":"2","function":"Control Grid 2 (Triode section 2)","function_code":"g1_2","notes":null},{"pin_number":"3","function":"Cathode 2 (Triode section 2)","function_code":"k2","notes":null},{"pin_number":"4","function":"Heater","function_code":"h","notes":null},{"pin_number":"5","function":"Heater","function_code":"h","notes":null},{"pin_number":"6","function":"Anode 1 (Triode section 1)","function_code":"a1","notes":null},{"pin_number":"7","function":"Control Grid 1 (Triode section 1)","function_code":"g1_1","notes":null},{"pin_number":"8","function":"Cathode 1 (Triode section 1)","function_code":"k1","notes":null},{"pin_number":"9","function":"Heater center tap","function_code":"h","notes":null}],"specs":[{"key":"Vh","display_name":"Heater Voltage","value":"6.3","numeric_value":"6.3","unit":"V","param_group":"heater"},{"key":"Vh","display_name":"Heater Voltage","value":"12.6","numeric_value":"12.6","unit":"V","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.3","numeric_value":"0.3","unit":"A","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.15","numeric_value":"0.15","unit":"A","param_group":"heater"}],"sections":[{"section_number":1,"section_label":"Triode","tube_type_key":"small_signal_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":"2.75","numeric_value":"2.75","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"20","numeric_value":"20","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"200","numeric_value":"200","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"2.2","numeric_value":"2.2","unit":"MΩ","param_group":"absolute_max"},{"key":"Va","display_name":"Anode Voltage (typical)","value":"250","numeric_value":"250","unit":"V","param_group":"typical_operating"},{"key":"Vg","display_name":"Grid 1 Bias Voltage","value":"-8.5","numeric_value":"-8.5","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"10.5","numeric_value":"10.5","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"7700","numeric_value":"7700","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"2.2","numeric_value":"2.2","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"17","numeric_value":"17","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.5","numeric_value":"1.5","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"1.8","numeric_value":"1.8","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"2.0","numeric_value":"2","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T19:00:36.321Z"}