Sophie Electric

Sophia Electric™ Royal Princess™ 300B Valves for 300B Amplifiers

Sophia Electric applied all expertise learned from the past to this new flagship Royal Princess 300B model. It has the best virtues of both Princess Mesh Plate and Princess Carbon Plate 300B valves and sound light-years ahead of any 300B tubes made in the history including both Sophia Electric Princess Carbon Plate 300B and Princess Mesh plate 300B valves that won worldwide praises.

From the outside, the Royal Princess 300B valve looks similar to Carbon Plate Princess 300B (share the same glassware enclosure), however, the design philosophy is quite different and the internal design and material is different as well. You have to listen to it to hear the dramatic sonic upgrade. I am confident that you will report the positive outcome once you have tried the Royal Princess 300B valves.

SPECIAL OFFER for UK customers!

For all orders placed by end of December 2012, Royal Princess 300B valves are available in a special price:

£ 950 - matched pair with one year warranty

The special price will be ended by the end of December 2012.
Act now before the price goes up!

  • Nominal operating conditions and parameters:
  • Filament voltage

    5,0 V *

  • Nominal filament current

    1,2 A

  • Plate voltage

    300 V

  • Grid voltage (AC filament)

    61 V **

  • Grid voltage (DC filament)

    58 V ***

  • Plate current (AC filament)

    60 mA

  • Plate current (DC filament)

    62,5 mA

  • Grid to plate transconductance

    5700 Ω

  • Amplification factor


  • Grid current

    0.05 µA

  • Plate resistance

    700 Ω

  • Limiting Operation conditions for safe operation-nor simultaneous ratings:
  • Maximum plate voltage

    450 V

  • Maximum plate dissipation

    40 W

  • Maximum plate current of average tube for fixed grid bias

    70 mA

  • Maximum plate current for manually adjusted grid or self-biasing circuit

    100 mA

* - AC filament supply or DC filament supply.
** - AC filament supply is used. The grid and plate returns should be connected to a center tap on the secondary of the filament transformer.
*** - DC filament supply is used. The grid and platter returns are connected to the negative end of the filament.


Option 1: Premium matched pair with one year warranty.


All prices include VAT.

Orders and warranty