Sovtek ECC83 / 12AX7LPS
This is an entirely new 12AX7 design from Sovtek and a great step up in sound quality. They have very large ribbed plates and great sound reproduction. They are very smooth and well balanced in terms of bass, mids and treble response. The large plates make them more prone to microphonics in combo amps, so they can be a problem if you like to run things wide open.