{"type_number":"ECC31","canonical_url":"https://tubeofile.com/tubes/ECC31","manufacturer":"Mullard","tube_type_key":"small_signal_triode","tube_type_display_name":"Small Signal Triode","base_name":"Octal","description":"Medium-mu double triode with common cathode. Designed as a voltage amplifying triode and low-power output valve, suitable for RC-coupled amplifier and Class A push-pull driver stages.","is_directly_heated":false,"completeness":"high","notes":["Common cathode — both triode sections share a single cathode (pin 8). Individual cathode biasing per section is not possible.","6N7G is often listed as equivalent but has different characteristics: lower heater current (0.8A vs 0.95A), higher mu (35 vs 32), and lower ra (11 kOhm vs 14 kOhm). Not a drop-in replacement in critical applications.","Half-screened envelope distinguishes it visually from the ECC32, which has a fully screened envelope and separate cathodes."],"references":["https://www.worldradiohistory.com/Archive-Catalogs/Suppliers/MNO/Mullard-Valve-data-book-1951-248-pages.pdf","https://www.r-type.org/exhib/aaa1556.htm"],"source_urls":{"r_type":"https://www.r-type.org/exhib/aaa1556.htm","tdsl":"https://tdsl.duncanamps.com/show.php?des=ECC31","radiomuseum":"https://www.radiomuseum.org/tubes/tube_ecc31.html"},"raw_equivalents":["CV1285","NR73"],"equivalents":[],"similar":[{"type_number":"6N7G","reason":"Similar type but different specs — mu 35 vs 32, ra 11k vs 14k ohms, heater current 0.8A vs 0.95A. Not a drop-in in critical applications","has_detail_page":false}],"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":"Anode 2","function_code":"a2","notes":null},{"pin_number":"4","function":"Control Grid 2","function_code":"g1_2","notes":null},{"pin_number":"5","function":"Control Grid 1","function_code":"g1_1","notes":null},{"pin_number":"6","function":"Anode 1","function_code":"a1","notes":null},{"pin_number":"7","function":"Heater","function_code":"h","notes":null},{"pin_number":"8","function":"Cathode (common)","function_code":"k","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":"0.95","numeric_value":"0.95","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":"5","numeric_value":"5","unit":"W","param_group":"absolute_max"},{"key":"Ik_max","display_name":"Cathode Current (max)","value":"25","numeric_value":"25","unit":"mA","param_group":"absolute_max"},{"key":"Vhk_max","display_name":"Heater-to-Cathode Voltage (max)","value":"50","numeric_value":"50","unit":"V","param_group":"absolute_max"},{"key":"Rg_max","display_name":"Max Grid Resistor","value":"1.5","numeric_value":"1.5","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":"-4.6","numeric_value":"-4.6","unit":"V","param_group":"typical_operating"},{"key":"mAa","display_name":"Anode Current","value":"6.0","numeric_value":"6","unit":"mA","param_group":"typical_operating"},{"key":"ra","display_name":"Anode Resistance","value":"14000","numeric_value":"14000","unit":"Ω","param_group":"typical_operating"},{"key":"gm","display_name":"Transconductance","value":"2.3","numeric_value":"2.3","unit":"mA/V","param_group":"typical_operating"},{"key":"mu","display_name":"Amplification Factor (μ)","value":"32","numeric_value":"32","unit":"—","param_group":"typical_operating"},{"key":"Cgp","display_name":"Grid-to-Plate Capacitance","value":"3.4","numeric_value":"3.4","unit":"pF","param_group":"capacitances"},{"key":"Cgk","display_name":"Grid-to-Cathode Capacitance","value":"4.0","numeric_value":"4","unit":"pF","param_group":"capacitances"},{"key":"Cak","display_name":"Anode-to-Cathode Capacitance","value":"1.9","numeric_value":"1.9","unit":"pF","param_group":"capacitances"}]}],"synced_at":"2026-04-07T12:38:38.559Z"}