Audio Database

SU-MA10
Commentary

Digital straight amplifier with twin monaural configuration using D. D. D. D.

Uses D. D. D. (Digital Direct Drive) system.
In this method, unlike conventional amplifiers with only a DAC mounted on them, the output signal of the DAC is increased to the voltage of the required sound level, and it is directly connected to a power amplifier with an amplification degree of 1 (0 dB) without going through the amplification path of the analog source. As a result, the output voltage of the DAC part is equal to the voltage of the speaker terminal, and excellent transmission characteristics are achieved.
In addition, in order to operate the 0 db power amplifier stably, it uses a combination of Technics original classAA and floating power supply to realize an S/N ratio of 140 db in the power amplifier section.
The D. D. D. cannot perform normal volume control, so a high voltage I/V converter is mounted on the DAC output as a voltage variable means. By changing the conversion ratio, the output voltage can be varied to adjust the volume.

MASH1-bit DAC is used for the D/A conversion part.
Mash reduces re-quantization noise in the audible frequency band by over-sampling 16-bit input data with a digital filter and then noise-shaping it. In addition, the PWM method, which in principle does not generate non-linear distortion such as 0 cross distortion, enables D/A conversion with extremely high accuracy, and enhances the reproduction capability of small signals, which tend to be buried in distortion components of high-level signals.

In order to reduce the jitter distortion in the digital transmission path, which is a problem in the amplifier with built-in DAC, a unique digital interface receiver is installed. This circuit reduces the jitter distortion by adopting the VCXO method using quartz with extremely high oscillation accuracy.
It is also equipped with a 2-PLL system with two VCoS to provide a 2-mode / 2-PLL system. The VCXO system is automatically selected for sources with high oscillation precision such as CD players, and the 2-PLL system is automatically selected for sources with low oscillation precision.

The power supply section is equipped with a 300 VA high-capacity transformer independently on the left and right sides. This transformer is used with a magnetic flux density approximately 30% lower than usual, minimizing mechanical vibration and magnetic radiation.
A newly developed X-Pro twin capacitor is used for the electrolytic capacitor. Two electrolytic capacitors for the positive and negative power supply are enclosed in a resin case with a copper cap. The capacitor is filled with vibration absorbing material to reduce mechanical vibration and electromagnetic radiation.

The power amplifier section has a twin monaural configuration in which the left and right sides are independent. In addition, the preamplifier section and digital section have a T-shaped configuration with a tight shield. This minimizes interference between the left and right channels caused by electromagnetic waves from the large current of the power amplifier section, and prevents noise from entering the final 0 db amplifier.

In addition to digital inputs of two optical and two coaxial systems, four analog inputs are installed.

Model Rating
Type Digital straight amplifier
Power Amplifier Unit
Effective power 100W + 100W (6 Ω, 20 Hz to 20 kHz, T. H. D 0.007%)
Total harmonic distortion factor 0.003% (20 Hz to 20 kHz -3dB, 8 Ω)
Damping factor 110 (8 Ω)
55 (4 Ω)
Preamplifier Section
Frequency characteristic Tuner, aux1/2, tape, DAT : 0.8 Hz to 120 kHz + 0 to 3 dB
20 Hz ~ 20 kHz + 0 -0.2 dB
Input Sensitivity / Impedance Tuner, aux1, tape, DAT : 150mV/100k Ω
aux2 : 150mV/22k Ω
Signal-to-noise ratio Tuner, aux1/2, tape, DAT : 105 dB (IHF' 66)
Digital Part
Total harmonic distortion factor 0.005% or less (EIAJ)
Frequency characteristic 2 Hz to 20 kHz ± 0.3 dB
<General>
Pwer 100 VAC, 50Hz/60Hz
Power consumption 250W
External dimensions Width 430x Height 186x Depth 433 mm
Weight 25.0kg