Vacuum tube type stereo power amplifier with direct heating triode GM70. Plate voltage 1,050 V, output 30 W+30 W. No-feedback technology creates a three-dimensional effect and a sense of presence, and expresses a clear sound.

Stereo Power Amplifier GM70PA


Former Soviet triode GM70

Equipped with the former Soviet GM70 with Pp=125 W. With a plate voltage of 1,050 V, 30 W+30 W (4 Ω) and 20 W+20 W (8 Ω) output, it can drive low efficiency speakers. *Two models with graaphite plate and copper plate.


Two-stage configuration with C3g

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. The C3g is soldered directly onto the board to reduce noise at the contact point.


Large output transformers

The large output transformer developed exclusively for this product is installed. Multi-layer sandwich winding drives both small and large signals over a wide bandwidth. Low winding resistance and drive capability, so it has a damping factor of more than 5 despite being a no-feedback amplifier.


Normal, Dual, Bridge mode switching

One more unit can be used as a bi-amp to drive the high and low frequencies. In bridge mode, the output can be driven by 1.5 to 2 times.

*Except in normal mode, it is valid for Lch/XLR input.

GM70PA_LE2.png GM70PA_wave.png There are two front panels to choose from: one with a graceful design that complements the music, and the other with a wave pattern that expresses harmony with the music.


Model GM70PA-G / GM70PA-C
Type Class-A Vacuum tube stereo power amplifier
Output Power

[Normal, DualMono]

・30 W+30 W(4 Ω, THD 5%)

・20 W+20 W(8 Ω, THD 5%)


・60 W(8 Ω, THD 5%)

・40 W(4 Ω, THD 5%)

*The other than normal is valid for Lch/XLR input.

Frequency Response 20-30 kHz -2 dB/10 W

[Normal, DualMono]

・0.7%/10 W

・0.2%/1 W


・0.5%/10 W

・0.1%/1 W

NFB None
Signal to Noise Ratio 90 dB/1 W(20-20 kHz)
Crosstalk 40 dB/1 W(20-20 kHz)
Input Sensitivity

[Normal, DualMono]

・1 V/30 W(4 Ω)

・1 V/20 W(8 Ω)


・1 V/60 W(8 Ω)

・1 V/40 W(4 Ω)

Gain 21 dB
Input Terminal Unbalanced x1, Balanced x1
Input Impedance 2.5 kΩ 1 kHz
Mode Switching By the rear rotary switch
Volume Adjustment None
Damping Factor

2.8(4 Ω), 5.6(8 Ω)

Power Supply AC100/120/200/240 V, 50/60 Hz
Power Consumption 400 W
Dimensions 470W×201H×430D mm *
Weight 27 kg
Finishing Anodic oxide coating

Rhodium-plated AC cords

Warranty Period 5 years(Excluding consumables)

* Knobs and terminals are not included.

  • The input impedance of this unit is 2.5 kΩ. Please use a equipment with an output impedance of 500 Ω or less.
  • The standard model is equipped with the GM70 graphite plate. (Model: GM70PA-G). A model with a copper plate (Model: GM70PA-C) is available as an option.
  • 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.
  • ■Dimensions

  • ■Catalog