Monaural Power Amplifier 212PA

Vacuum tube type monaural power amplifier with large triode 212E. Plate voltage 1,400V, output 40W. No-feedback technology creates a three-dimensional and spontaneous sound.

Large triode 212E
The 212E is a transmitter and modulation tube with a plate loss of 275W, developed by Western Electric in the 1910s. Class-A single tube amplifier has difficulty driving a low efficiency speaker, but this unit has a plate voltage of 1,400V and an output of 40W. The damping factor of 5 or more is achieved by reducing the output power, so it can drive the low frequency range reliably.

*Two models are available: STC’s 4212E (1960-70s production) and Jinzhou Electronics’s 212E.

Two-stage configuration with C3g
It is equipped with the ultra-reliable C3g, developed by Deutsche Telekom for telephone repeaters. The thin grid lines and large distance between electrodes enable high linearity amplification. By using only two tubes of amplification with the 212E, harmonics and mixed-modulation distortions are suppressed though no-feedback.

High fidelity input transformer
The input transformer makes up for the lack of gain in the two-stage amplification. It is received by a high linearity transformer with a high permeability super permalloy core and does not add anything extra.

* The input impedance is 1.5kΩ, and should be driven by equipment with an output impedance of 300Ω or less.

Original design and development of dual regulated power supply
It employs a dual regulated power supply with a switching regulator in the first stage and an after-analog regulator in the second stage, which has been optimized for audio based on many years of knowledge in power supply development.


Model 212PA-ST / 212PA-JH
Type Class-A Vacuum Tube Monaural Power Amplifier
Output Power 40w(4Ω, 8Ω)
Frequency Response 20-40kHz -3dB/20W
THD 1%/40W 1kHz, 0.2%/10W 1kHz
NFB None
Signal to Noise Ratio 90dB/10W(8Ω)
Input Sensitivity 1V/40W
Gain 25dB(8Ω)
Input Terminal UNBALANCED x1
Input Impedance 1.5kΩ
Volume Adjustment By the front volume
Dumping Factor 5 or more
Power Supply AC100/120/200/240V, 50/60Hz
Power Consumption 400w
Dimensions 188W×385H×563Dmm *
Weight 24.5kg
Finishing Anodic Oxide Coating, Rosewood Plates
Accessories AC Cords
Warranty Period 5 years(Excluding consumables)

* Knobs and terminals are not included.

  • The input impedance of this unit is 1.5kΩ. Please use a equipment with an output impedance of 300Ω or less.
  • Two models are available: STC 4212E (model: 212PA-ST) and Jinzhou Electronics 212E (model: 212PA-JH).
  • The 4212E made by STC is a rare item, so please contact us for availability.
  • Do not touch the vacuum tube as it is hot and may cause burns.
  • Vacuum tubes are treated as consumables and are not covered by warranty.
  • Product appearance and specifications are subject to change without notice.