12ax7 Preamp Vacuum Tube, Able to Replace Ecc83/5751/ecc803s/7025, for Guitar/amplifier High performance vacuum tube.Glass enclosuredirect thermalfull-wave rectifier. Low noise and low microphonics - Hand selected and tested. Great tone and break-up characteristics for guitar, hi-fi tube amps and microphone. Rugged construction for longest life. Anode is made of pure graphite. Able to replace ECC83/5751/ECC803S/7025. Available in matched Pairs.