Amazing sound and build quality. I spoke with Sophia Electric directly and very few of these were produced. The equivalent monoblocks now cost $18,000. No boxes so local pickup only. PRICED AS A PAIR together; my asking price is NOT for each unit. All tubes included.
In speaking directly with Sophia Electric, they advise the units were manufactured in 2005. The driver tubes are 206. The main tubes are 845. The amps are Single Ended (not push-pull). Is it quite powerful for the design. You rarely get this Single Ended design with a high watt output, thus the normal high cost for these type of amps.
Approximate dimensions are 16" x 12" x 10.5" height at the peak of the highest tube.
Regarding the tubes presently in the mono blocks:
#1 Sophia 206; #2 274B Shuguang; #1 845 Shuguang (also I'll include #4 more 274B's from the Tube Store in Canada)
The Sophia Princess 206 is a hybrid of 300b and 205D in electrical character and has a big open sound unheard of from any 300b/2A3/45 tube (much like 845 with smaller power).
Sophia Electric™ amplifier designers have successful used 205D tube in the amplifier design as driver tube, (such as 205D drive 845 amplifier currently available) and as output tube in single ended and push pull design in various proto type amplifiers. As output tube, 205D has 1-1.5W in single ended power, far less than needed for most speakers, except horn speakers above 100dB efficiency.
Rather than parallel the 205D in two or three units per channel, our engineers enlarged the plate size by three times. It offers 5-6 watts of Single ended power or 15-20 watts in Push and pull design.
Overall Sonic Character:
S.E.T. Princess™ tube has all the characters of 300b and 205D, and adds far more sonic beauty to music. Big, open sound like 845, Sweet like 300b, delicate like 45 and 205D.
Typical single ended operating point: 4V/1.25A filament, 350V - 400V plate voltage, -24V bias (50-60ma bias current), 2.5-3K output transformers, same as the ones in a typical 300b/2A3 amp. Current 300b/2A3 users can parallel a 1K/30W or 15Watts Caddock resistor to the existing 800 ohm to 1K cathode resistor to enjoy the beauty of S.E.T. Princess™ 206 tube.
274B from the Tube Store is a full-wave rectifier that is very similar to the classic 5U4G. This 274B tube's filament draws 2.5A of current. This current draw makes it acceptable for many amps originally designed for a 5AR4/GZ34 tube. Our PS-274B tube is a beautiful large coke bottle shaped rectifier tube with large black plates. The installed height is 5 inches. It's width is 2.5 inches at the widest point.
This tube is produced for us in China by the Shuguang factory. A new evacuator is utilized for a much longer time period increasing vacuum over 100 times more than their current 5U4G tube. A new cathode coating process provides a much smoother finish improving electron flow and they are burned in at high voltages for a much longer time for improved stability. The end result of utilizing these new production materials, techniques, and equipment is a premium rectifier tube at a much lower cost than the NOS Western Electric 274B.
Like the 211 tube, the Shuguang 845 tube is a transmitting triode tube that combines wall shaking power and great sound reproduction. The Shuguang 845 is fast and clean sounding, with good tonal balance with a slightly forward midrange. It has good detail and smoothness, but a little edge in the midrange. This tube is the choice of most OEM's requiring the 845 tube. Great amps such as the Cary CAD 805, Aries 845-G monoblocks, Unison S8, and many others use this 845 tube.
The Shuguang 845 tube has a thorium-tungsten filament.