{"type_number":"12AX7","canonical_url":"https://tubeofile.com/tubes/12AX7","manufacturer":null,"tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Noval","description":"High-mu twin triode. Two identical triode sections with individual cathode connections. Primarily used for audio.","is_directly_heated":false,"completeness":"high","notes":["One of the most widely used small-signal tubes in audio, introduced in 1947.","The 7025 is a low-noise, low-hum version intended for high-gain audio preamplifier service.","The 5721 (12AX7WA) is the ruggedized military version with controlled heater warm-up.","The M8137 is the Mullard/CV military equivalent, highly sought after by audiophiles.","The 6057 and 6681 are GE special-quality versions with tighter parameter tolerances.","Can be operated with 6.3V or 12.6V heater supply using the pin 9 center tap.","The 5751 is often used as a lower-gain substitute (mu=70 vs mu=100) for reduced distortion."],"references":["https://www.drtube.com/datasheets/12ax7-rca1962.pdf","http://www.tubezone.net/pdf/12ax7ecc83.pdf"],"source_urls":{"r_type":"https://www.radiomuseum.org/tubes/tube_12ax7.html","tdsl":"https://tdsl.duncanamps.com/show.php?des=12AX7","radiomuseum":"https://www.radiomuseum.org/tubes/tube_12ax7.html"},"raw_equivalents":["ECC83","ECC803","ECC803S","7025","12AX7A","12AX7WA","12AX7S","M8137","CV4004","CV492","B339","B759","5721","6057","6681","7729","12DF7","12DT7","E2164","6L13","8339","E83CC"],"equivalents":[],"similar":[{"type_number":"12AT7","reason":"Same Noval dual triode pinout but medium-mu (mu=60) vs high-mu (mu=100); higher plate current, lower ra","has_detail_page":true},{"type_number":"12AU7","reason":"Same Noval dual triode pinout but low-mu (mu=17); much higher plate current, used as driver/buffer","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, reduced mu (mu=70); military grade, common lower-gain substitute","has_detail_page":true},{"type_number":"6SL7","reason":"High-mu dual triode (mu=70) but Octal base; similar application as voltage amplifier","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":"12.6","numeric_value":"12.6","unit":"V","param_group":"heater"},{"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":"0.15","numeric_value":"0.15","unit":"A","param_group":"heater"},{"key":"Ah","display_name":"Heater Current","value":"0.3","numeric_value":"0.3","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":"1.0","numeric_value":"1","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"8","numeric_value":"8","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"180","numeric_value":"180","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"2","numeric_value":"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":"-2","numeric_value":"-2","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"1.2","numeric_value":"1.2","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"62500","numeric_value":"62500","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"1.6","numeric_value":"1.6","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"100","numeric_value":"100","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"1.7","numeric_value":"1.7","unit":"pF","param_group":"capacitances"},{"key":"Cin","display_name":"Input Capacitance","value":"1.6","numeric_value":"1.6","unit":"pF","param_group":"capacitances"},{"key":"Cout","display_name":"Output Capacitance","value":"0.46","numeric_value":"0.46","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:04:18.818Z"}