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 Stradi RS242 is NOT 100% compatible with Telefunken RS242.
Be sure to consult a professional before use.

 This model has been improved to reduce microphonics, which is the most problematic in pre-amps using DHT tubes.

 We have developed and tuned this product for over 5 years. We hope listeners can fully focus on the music without microphonics, especially in pre-amps using DHT tubes.
All vacuum tubes we provide are improved for audio purposes, but this model especially has been made to enjoy music with wonderful sound.

The RS242 tube is a low-output transmitting tube developed by Telefunken.
Telefunken's RS242 has almost similar characteristics to Telefunken's RS241 except for the different types of filament.

  The different types of filament
RS241 : Azide Process filament
RS242 : Oxide-coated filament

However, as oxide-coated filament was used to manufacture Stradi RS241, the difference with Stradi RS242 disappeared.
So, we changed the electrical characteristics of our RS242 to the amplification factor of 21, not Telefunken RS242’s amplification factor -17-.

The Stradi RS242 tube is suitable to be used as a drive tube.
If the RS242 is used as a drive tube, the tube's amplification factor is important, but the amount of filament heat is more important when it comes to the sound quality.

If the amount of filament heat is insufficient, the bass sounds weak, and if the amount of filament heat is excessive, the sound is harsh.

The Stradi RS242 tube has an appropriate amount of filament heat to bring out good sound, and has a higher amplification factor than RS241.
Therefore, it is suitable for some driving output tubes (eg: DA30) that uses a high supply voltage with a low amplification factor.
These are things that RS241 cannot do because it is difficult to get enough drive voltage.

The Stradi RS242 tube is extremely suppressed in generating microphonic, which is the biggest problem when using a direct heating tube.
If you use the Stradi RS242 tube, you can focus on music without thinking of microphonics in DHT Phono Amp or DHT PreAmp, which was previously considered impossible to use.

Available in matched pairs, quad sets, and singles.

  • Availability In Stock
  • Lead Time 3 ~ 14 days
  • Price$390.00

  • Note: Higher amplification factor than original Telefunken RS242
  • Ladder type Frame Grid
  • Material of minimizing filament end-loss
  • Anti-microphonic structure
  • Electrophoresis filament coating
  • Dual Getters
  • Eco-friendly paper packaging


  • Filament Voltage : 4 Volt (AC or DC)
  • Tolerance on filament voltage : +-2.5 %
  • Filament Current : 0.77 Ampere


  • Maximum Anode Voltage : 400V
  • Maximum Anode Dissipation : 12Watt
  • Maximum Anode Current : 40mA


  • Anode Supply Voltage : 300V
  • Grid Voltage : -7V
  • Anode Current : 8mA
  • Transconductance : 3000 µmhos
  • Anode Resistance : 7000 Ω
  • Amplification factor : 21