Tube Amp Doctor 12AY7 Highgrade Vacuum Tube

High grade tube. Tweed Up Your Amp! Vintage tone for original vintage Fender tweed amps. The original tube for all those Fender® tweed amps from the 50s. Brings back the original sound to your tweed amp. The HIGHGRADE Selection is the tip-of-the-top quality at the lowest noise (microphony, hum, hiss) level. Typically only 0.5-2% out of the whole production of this tube meet the HIGHGRADE requirements. Q: When does a preamp tube become a Premium Selected tube? A: All preamp tubes labeled Premium Selected have passed the following tests: - Low Noise Test - Microphonic Test - Gain Test - Sonic Tests - Shock Tests - Listening Tests - Balanced Output Test