Audio Database

Stereo power amplifier with high power design of 400W + 400W.

All stages of complimentary service circuit is adopted for circuit structure.
The first stage is a differential-amplified dual complimentary service circuit, and the pre-driver stage is a push-pull amplified full complimentary service circuit. Up to this point, the amplification is class A. The driver stage is divided into Pch and Nch, amplified by a push-pull amplified complimentary service circuit with separate transistors, and connected to the complimentary service stage of the full output circuit. This characteristic circuit is called a PSO (Parallel-Series-Output) circuit.
In general power amplifier designs, the circuit system from a single-configuration driver stage to a differential amplifier output stage cannot avoid low-frequency modulation noise for a large output and causes a decrease in SN ratio. However, by adopting a PSO circuit, a low distortion factor is realized over a wide band.

Various considerations have been added to the transformer used in the power supply section to cope with high power.
For example, the winding is designed to have a square cut surface, and the mixture ratio of copper and iron in the material is carefully examined. This realizes an efficient transformer with low heat generation. A pair of capacity of this transformer is equivalent to four computers storing 175 joules of energy, and the change from load 0 to saturation is limited to 10%.
In addition, by installing an independent regulator for each channel of the differential input stage, accidents that may occur in each circuit can be prevented.

In order to dissipate the enormous heat generated by 8 driver transistors and 16 output transistors, a heat sink car with a long protrusion is adopted. This heat sink allows air for cooling to flow in and out easily. Moreover, the total surface area exceeds 1000 square inches and has a high cooling capacity.
In addition, stability is improved by feeding open air with a high-speed fan.

Carefully selected parts are also used, such as Mil-Spec glass epoxy board and metal / carbon film resistance.

Model Rating
Type Stereo power amplifier
Effective power 600W + 600W (4 Ω)
400W + 400W (8 Ω, 20 Hz to 20 kHz, double-channel drive, 0.05% distortion factor)
Total harmonic distortion factor 0.05% (20 Hz to 20 kHz, 8 Ω, 250 mW to 400W)
Cross modulation distortion factor 0.05% (250 mW to 400W, 8 Ω, 4 : 1 mixture of any two frequencies between 20 Hz and 20 kHz)
Frequency characteristic 20 Hz ~ 20 kHz ± 0.25 dB (at Rated Output)
Signal-to-noise ratio 100 dB (at rated output)
Damping factor 150(100Hz)
Input terminal Route 1
Input Sensitivity / Impedance 2.12V/50k Ω
Input level adjustment Left / Right Independent PushButton Type 4-Step Gain Switching
(0, -3, -6, -12dB)
Meter sensitivity Left-Right Interlocking Push-Button Type 4-Step Switching
(0, -6, -12, -24dB)
Attachment Cooling fan
Pwer 100 VAC, 50Hz/60Hz
Power consumption 1,500W (at rated output)
External dimensions Width 483x Height 178x Depth 461 mm (including terminals and handles)
Weight 29.5kg