Audio Database


High-quality monaural power amplifier with UHC single push-pull circuit.

UHC-MOS (Ultra High Current-MOS) is used for audio circuits for the first time.
This device has an improved gm (amplification factor) compared to bipolar transistors, enabling current linearity equivalent to 35 MOS-FETs and 3 bipolar transistors, which are commonly used, with a single device.
As a result, we have completed a single push-pull circuit that can handle low impedance loads and withstand large currents.

Cascode bootstrap connection is used for the circuit configuration.
By keeping the voltage applied to the UHC-MOS constant, we solve the problem of large junction capacitance, and by realizing high temperature stability, we take advantage of the acoustic characteristics of the UHC-MOS even under severe operating conditions.
In addition, this circuit achieves a simple and straight configuration of two voltage amplification stages and one power amplification stage without burdening the voltage amplification stage.

Stable operation is realized by the UHC single push-pull circuit.
In addition, by eliminating the source resistor and output circuit coil, more high-purity transmission is possible.

The BTL circuit provides high output power at low power supply voltage, making it possible to use an excellent acoustic device.
In addition, by completely separating the output voltage of the speaker from the ground circuit that serves as the operating reference, adverse effects on the music signal are eliminated.

The power supply is equipped with two large toroidal transformers, which are connected in parallel to reduce the impedance of the transformer itself by half and improve the power supply capability.
We have also developed and adopted an open-type toroidal transformer that removes the upper case to completely eliminate internal resonance.

UHC-MOS is also used in the power supply circuit to greatly reduce power loss.
The current loss of the UHC-MOS is equivalent to approximately 40% of that of a Schottky barrier diode and approximately 20% of that of a general silicon diode (at 10A), enabling a current supply of as much as 240A.

In addition to the weight of the chassis structure, a direct mechanical ground structure is adopted to reduce the vibration from the large toroidal transformer and power radiator used in the output stage.
In this structure, the two large toroidal transformers and the heat sink are fixed directly to the leg, and there is no common vibration path with other peripheral circuits, so the influence on other parts of the set is eliminated.
As for peripheral circuits, the mounting base has sufficient weight to eliminate mutual interference.

Non-magnetic sand castings are used for the chassis and radiator.
In addition to the quick damping of vibration, sand castings have the effect of suppressing the generation of electro-magnetostriction caused by transformers and capacitors.

Model Rating
Type Monaural power amplifier
Rated output 1,400W (1 Ω, 1 kHz, 0.5% THD)
1,000W (2 Ω, 1 kHz, 0.5% THD)
500W (4 Ω, 1 kHz, 0.5% THD)
250W (8 Ω, 20 Hz to 20 kHz, THD 0.05%)
Total harmonic distortion factor 0.008% (20 Hz to 20 kHz, 8 Ω, Rated Output -3dB)
Cross modulation distortion factor 0.003% or Less (7 kHz : 60 Hz = 1 : 4, 8 Ω, Rated Output -3dB)
Output bandwidth 5 Hz ~ 50 kHz (THD 0.05%, 8 Ω, Rated Output -3dB)
Frequency characteristic 1 Hz ~ 300 kHz (8 Ω, 1W Output)
Input sensitivity Normal:1V
Input impedance Normal : 47k Ω
Balanced : 47k Ω
Output impedance 0.05 Ω (1 kHz)
Signal-to-noise ratio (A-curve weighting) Normal:110dB
Speaker output terminal 1 Ω or more
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 1,100W
External dimensions Width 483x Height 273.5x Depth 683.5 mm
Weight 79.0kg