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


Vacuum tube GM70

Equipped with vacuum tube 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 graphite plate and copper plate.


Two-stage 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.


Dual and bridge mode

It can be used as a bi-amp to drive high and low frequencies in dual mono mode with one additional unit, or in bridge mode to drive the output at 1.5 to 2x.

・These modes are available only with XLR balanced input.

Dual mono mode

Two GM70PAs drive the mid-high and low of the speakers

Bridge mode

Two GM70PAs drive the Lch and Rch of the speakers





Class-A Vacuum tube stereo power amplifier

Output Power

Normal, Dual mono

30 W+30 W (4 Ω, THD5%)

20 W+20 W (8 Ω, THD5%)


60 W (8 Ω, THD5%)

40 W (4 Ω, THD5%)

Frequency Response

20 Hz-30k Hz -2 dB/10 W


Normal, Dual mono

0.7%/10 W

0.2%/1 W


0.5%/10 W

0.1%/1 W



Signal to Noise Ratio

90 dB/1 W (20 Hz-20k Hz)


40 dB/1 W (20 Hz-20k Hz)

Input Sensitivity

Normal, Dual mono

1 V/30 W (4 Ω)

1 V/20 W (8 Ω)


1 V/60 W (8 Ω)

1 V/40 W (4 Ω)


21 dB

Input Terminal

Unbalanced x1, Balanced x1

Input Impedance

2.5k Ω/1k Hz

Mode Switching

By the rear rotary switch

Volume Adjustment


Damping Factor

2.8 (4 Ω)

5.6 (8 Ω)

Power Supply

AC100/120/200/240 V, 50/60 Hz

Power Consumption

400 W


470W×201H×430D mm


27 kg


Anodised aluminium


AC cords

Warranty Period

5 years

  • The input impedance of this unit is 2.5k Ω. 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.
  • Dimensions do not include legs, knobs, or terminals.
  • The descriptions are current as of March 31, 2023.
  • The appearance and specifications are subject to change without notice.
  • Actual colors may differ from those in the photographs due to photography, lighting, etc.

A2-0.jpg A2-6.jpg A2-D.jpg