"...the lineage of that amp goes back to a lunch at some crummy Chinese restaurant in Vegas in 1997, during CES. JT and I had been looking over some of the competition, and while waiting for our chow mein we put together a design on a napkin that we felt improved upon one or two of the more radical designs we had encountered that day. I think JT still has that napkin." - Doc Bottlehead "I remember hearing them at the very first VSAC-- and I was mesmerized with just how darn dynamic and unflappable the amp was--- I was stuned (sic) at the time. Kudos to John." - Mike LeFevre, Magnequest
Steve Brown (well-known Tube Head) and I each built one of these in 2006 after finding the Positive Feedback article that talked up it's virtues.
I decided to join my woodworking and amp building hobbies to create casework that complemented the "old time radio" tubes. The case is Padauk, finished with 12 individually hand rubbed coats of amber shellac. The Padauk has aged to a decidedly 'antiquey' rich red/brown.
This 1.8 Watt amp was my mainstay until a few years ago, paired with a very high quality Passive pre-amp; just an excellent volume control and switch that filled a 15'x18' room with sound from 97dB speakers. Various active pre-amps by CAT, DeHavilland, my own hand and others also satisfied and were more dynamic but I kept coming back to the purity of the Passive.
Construction details include Gabon Ebony feet, Edison Price Music Post terminals, Teflon Tube Sockets, Audio Note silver RCAs, and a combination of annealed silver, Vampire copper magnet, and copper XLO wires arrived at after extensive listening and tinkering.
Electronics include Audio Note Tantalum and Kiwame resistors, Film By-pass caps, Obbligato Oil Parafeed Caps, and the active Constant Current Source based on a Gary Pimm design with a large heatsink.
The Magnetics begin with the well-tried and quiet Hammond 373BX Classic Series power transformer, separate Hammond chokes for each side, separate output tube filament transformer then finish up with Magnequest BCP-15 Plate Chokes and Robin Hood Nickel Pin-striped Parafeed output transformers.
After the single power transformers the Power Supply design is entirely dual mono for exceptional channel separation.
To help ensure that your enjoyment will equal mine I am including my entire tube complement used during the last two years it was in service: late 1930s National Union and RCA Cunningham UX-45s, Bugle Boy 5AR4 rectifier, and Sylvania 5965 driver tubes
Here's Steve Brown commenting in an Audio Asylum thread soon after the completion: "I'll chime in and 2nd Bill's comments. Very nice amp. Amazing how much definition there is around the individual notes. We did make a couple of slight alterations, but the character is the same. The one significant change was adding some B+ bias to the heater on the driver to kill some hum. To do that we added a 39k 1w in series w/the 270k bleeder, and paralleled the 39k w/22uf, then ran that to pin 9 of the driver. That made this the quietest SET I've ever auditioned. The other change is that Bill made this a stereo amp, but built in dual-mono power supplies."
What all this results in is an amplifier with exceptional purity of tone and timbre that truly places small voice and instrumental soloists and ensembles in the room. Within the limitations of it's power output it also does a surprising job of presenting larger forces. The Parafeed output configuration ensures powerful and accurate bass.
Two years ago I completed a pair of 60 Watt mono blocks that I confess have taken over my listening and the 45 has become a lovely piece of furniture (see last pic) that I continue to enjoy solely for it's appearance. It seems a shame that it should sit like that when it could be bringing some one else the pleasure I've had from it. Acquire it, place it where you can see it and play the great music of your taste.