Sophie Electric

Sophia Electric™ S.E.T Princess™ 206 Mesh Valves

Introduced at CES Show in Las Vegas on January 9, 2003, S.E.T.Princess™ Tube of Sophia Electric™ in Washington, DC could be the world's best sounding tube ever. It 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).

The story:
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, and made the filament voltage of 5V instead of 4.5V that made it possible to use this tube in a 300b amplifier circuit with minimum of modification. Thus the S.E.T. Princess tube is created. (note: this new tube is a lot of easier to drive than 300b).

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. It offers 5-6 watts of Single ended power or 15-20 watts in Push and pull design.

Typical single ended operating point: 5V/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™ tube.

Interested party should read the specification, Please consult with your amplifier maker for needed upgrades to use S.E.T.Princess™ tubes.

New design ST shape glass enclosure. Four-pin socket(like 300b base), Direct Heating oxide coated filamentary triode.

Audio amplifier Class A service
Radio amplifier Class B service
Oscillator Class C service


  • Nominal operating conditions and parameters:
  • Filament voltage

    4,0 V

  • Nominal filament current

    1,2 A

  • Plate voltage

    400 V

  • Grid voltage

    -24 V

  • Plate current

    50 mA

  • Plate resistance

    2500 Ω

  • Amplification factor



Option 1: Premium matched pair with one year warranty.

Option 2: Premium matched pair with 30 days warranty.

Option 3: Standard matched pair with 30 days warranty.


Orders and warranty