MESA Engineering 12AX7 ECC83 Preamp Vacuum Tube - Strong B&K 747 Tested
$24.95
Genuine MESA Engineering branded 12AX7/ECC83 high-gain dual-triode preamplifier vacuum tube. The original MESA Engineering branding remains visible, although portions of the printed markings show normal age and handling wear.
This individual tube was bench tested on a B&K Model 747 Dynamic Mutual Conductance Tube Tester. Both triode sections tested strongly within the GOOD range. Triode Section 1 measured approximately 95, while Triode Section 2 measured approximately 85. The sections are both strong but are not represented as balanced.
The 12AX7 is a nine-pin high-mu dual triode commonly used in guitar amplifiers, bass amplifiers, hi-fi equipment, stereo systems, microphone preamplifiers, voltage-amplifier stages, driver stages, and phase-inverter circuits. The photographs show the actual tube and its individual test results.
Historical Note: MESA Engineering, commonly known through the MESA/Boogie amplifier brand, has supplied selected and branded preamplifier tubes for use in professional guitar and bass amplification equipment. MESA-branded 12AX7 tubes have been widely used as original equipment and replacement tubes in high-gain amplifier circuits.
Origin Tracker
Bench Stock
Pulled from RF Boneyard bench/service stock for practical repair and restoration use.
Pipeline quantities are informational and may change after arrival, inspection, sorting, testing, or donor teardown.
Compatible Radios / Boards
Compatible with equipment designed for 12AX7, 12AX7A, ECC83, 7025, and equivalent nine-pin high-gain dual-triode vacuum tubes where circuit requirements permit. Suitable for many MESA/Boogie and other compatible guitar amplifiers, bass amplifiers, hi-fi amplifiers, stereo equipment, tube preamplifiers, microphone preamps, driver stages, and phase-inverter circuits. Buyer should verify the required tube type before installation.
RF Boneyard Bench Notes
Tested on a B&K Model 747 Dynamic Mutual Conductance Tube Tester. Triode Section 1 tested at approximately 95 within the GOOD range. Triode Section 2 tested at approximately 85 within the GOOD range. Both sections tested strong but are not represented as balanced. Heater operation confirmed and no shorts indication was observed during testing. Noise and microphonics were not evaluated. Actual tube and test photographs are included.
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