Correct, it is a "one-off" we built here a few years ago.
It has a regulated high voltage power supply board squeezed in instead of our standard big R/C passive supply used in this unit.
We wanted to see if this would be a cost effective improvement. We did not have the physical room or voltage head room for the best possible regulated power supply, one with eight active regulators. This unit has a single high voltage active B+ supply regulator, shared by all the tubes.
It certainly did make a useful musical improvement, but not enough in our judgement to justify the engineering time and tooling cost to offer it as a production improvement to our PAS preamp rebuild kit. It would have taken a new PC card design and a complete re-write of the rebuild kit manual.
20 years earlier, when there was a large pool of stock PAS units around to improve, the redesign cost might have been justified. But now it probably is not for us.
The unit offered on e-bay should be a really nice performing unit, a true AVA one off piece.
Regards,
Frank Van Alstine
