- Stereo Power Amplifier
GM70PA
- Vacuum tube type stereo power amplifier with direct heating triode GM70. Plate voltage 1,050 V, output 30 W+30 W. It creates a sense of three-dimensionality and realism with non-feedback, and expresses clear sound.
- Direct-heating triode GM70
- Large output transformers
- Doubly regulated power supply
Features
- Direct-heating triode GM70
- Equipped with direct-heat triode GM70 tube with Pp=125W, which is larger than 845 (Pp=100W) and has low impedance. Output power is 30W + 30W (4Ω load) and 20W + 20W (8Ω load), driving even low-frequency speakers that have become mainstream in recent years.《There are two models: graphite plate and copper plate.》
It also has dual -mono mode and bridge mode functions.
○ Dual-Mono: Drives the mid-high and low frequencies of the speaker by preparing two GM70PAs.
○ Bridge: Drives the Lch and Rch of the speaker from 1.5 to 2 times the output by preparing two GM70PAs.
* Effective when Lch/XLR input is used.
- Two-stage with C3g
- Equipped with the ultra-reliable C3g, developed by Deutsche Telekom. The thin grid lines and large distance between electrodes enable high linearity amplification. Using only two tubes of amplification with the GM70, harmonics and mixed-modulation distortions are suppressed though no-feedback.
- Large output transformers
- Multilayer sandwich winding provides wide bandwidth drive from small to large signals. Large damping factor of 5 or more for a non-feedback amplifier, Low winding resistance ensures reliable low-frequency drive.
- Doubly regulated power supply
- Rectifiers used in general power supplies and contacts are noise sources. These are sharp-rising noises that span from 50 Hz to several hundred MHz and muddy the sound. To solve this problem, a switching power supply has been optimized for audio applications based on our half-century of knowledge in power supply development. The high voltage of 1,050V supplied to the GM70 is doubly regulated by the switching power supply and analog power supply, enabling quiet output with no distortion.
Specification
Model GM70PA-G / GM70PA-C
Type 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%)
○ Bridge
60 W (8 Ω, THD5%) 40 W (4 Ω, THD5%)
Frequency Response 20 Hz-30k Hz -2 dB/10 W
THD
○ Normal, Dual mono
0.7%/10 W 0.2%/1 W
○ Bridge
0.5%/10 W 0.1%/1 W
NFB None
Signal to Noise Ratio 90 dB/1 W (20 Hz-20k Hz)
Crosstalk 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)
○ Bridge
1 V/60 W (8 Ω) 1 V/40 W (4 Ω)
Gain 21 dB
Input Terminal Unbalanced x1 Balanced x1
Input Impedance 2.5k Ω/1k Hz
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 Anodised aluminium
Accessories 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 January 2025.
○ The appearance and specifications are subject to change without notice.
○ Actual colors may differ from those in the photographs due to photography, lighting, etc.
