Sophie Electric

Sophia Electric™ S.E.T. Princess™ 300B 2.5V Mesh Plate Valves for 2A3 Amplifiers

Introducing the latest Sophia Electric "S.E.T.Princess 300B 2.5V" valves. This Princess 300B 2.5V mesh plate valve is the upper class model of the current 300B 2.5V line (globe shape is still in production). This new valve is using the same 300B 2.5V plate (as the globe 300B 2.5V) with stronger plate structure learned from making the original Princess valves. It will work with all 2A3 amplifiers.

The glass enclosure was from the Princess valve for its unmatched sonic beauty. The shape of glass enclosure does make a major difference. Just thinking of violin's shape, if it gets changed to triangle, the sound character of violin will change for sure.

The Princess 300B 2.5V mesh plate valve has more volume and more curved than the old ST. It is not the old ST came back rather it is a carefully crafted, researched new 300B 2.5V model. The result is it has super clarity, low distortion and out of this world mid range fullness and liquidity. High frequency extension and sweetness is the first thing you would hear.


  • Nominal operating conditions and parameters:
  • Filament voltage

    2,5 V *

  • Nominal filament current

    2,5 A

  • Plate voltage


  • 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 direct-current 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.

Sophia Electric™ S.E.T. Princess™ 300B 2.5V mesh tube plate curves


Option 1: Premium matched pair with one year warranty.

Option 2: Premium matched pair with 30 days warranty.

All prices include VAT.

Orders and warranty