yes, the circuit design was by private consulting with R Waters
who has great experience using computer design to optimize tube audio circuits, in order to get the highest performance possible with the least amount of added distortion due to the necessary additional gain needed to overcome the high losses in a tone
control circuit. He did an original design for the PAS3 upgrade about a year ago and then
I asked him to let me license the design to my specific needs. Then the PCB layout was done by myself optimizing the traces, layout,
and ground planes, and integrating my tube preamp power supply.
The 16" chassis is available completely undrilled, or finished and ready to install all components, just like all of my preamp designs.
There is also a 12" version available if you don't need room for a phono preamp.Tubes4HiFi preamps link