This is a lower gain 12AX7 tube type. Stevie Ray Vaughn used
these to change his front end distortion to back end distortion ratio to have
more of the touch sensitive output tube distortion.
These test as per 5751 spec with the proper transconductance and current
output.
The slightly lower gain quiets many amps down and these are a very smooth
front end tube but are also quite amazing in the phase inverter position.
In the Fender Hot Rod series these are really the rage these days with many
of GT's folks that use these amps.
