Accuphase PS-550 Clean Power Supply

Amazingly pure energy source

Every audio component draws all of its energy from the power supply which in turn is connected to the AC power grid. The Clean Power Supply components from Accuphase are products that remove noise and impurities from the AC power line through a groundbreaking new approach, resulting in a drastic improvement of the sound and picture quality of connected audio and video equipment. Without relying on an oscillator, the reference waveform is created with further improved accuracy and is linked to the power section by a balanced connection to ensure incredibly low distortion in the output waveform. 

Low-distortion reference waveform generator

To generate the 230 V (120 V) sine wave reference signal, the zero-cross point at the secondary winding of a measurement circuit transformer is detected by a comparator and used by the high-precision power supply to generate a square waveform. The square wave then is routed through a newly developed 50/60 Hz band pass filter and a six-stage band elimination filter (BEF). The filter frequency is switched in sync with the input frequency, for automatic 50 Hz and 60 Hz support. By routing the signal through another band pass filter, a low-distortion sine wave (reference signal) is created that is not dependent on the input voltage.

Outstanding waveform compensation power

Figure (a) shows a severely distorted waveform such as commonly encountered in ordinary AC outlets at home. Simple filtering will never be able to bring this waveform back to the intended shape. Figure (b) shows the condition where noise is affecting the AC power. Filtering will be able to remove some of the higher frequency noise components but low frequency components are very difficult to remove. The PS-530 incorporates power waveform shaping technology that uses a clean reference waveform and works in real time to provide exactly the required compensation and remove any unwanted components. Distortion is reliably eliminated and the result is a perfectly clean source of energy.

Power supply waveform and clean PS-530 output waveform

Almost all electrical devices used in a household convert the AC supplied by the outlet into a DC current for powering internal circuits. This task is performed by a rectifier. The rectifier load current has a pulse waveform with a large current flowing momentarily in the vicinity of the voltage peak. This causes a voltage drop, resulting in clipping of the voltage waveform. A clipped waveform with a high amount of distortion contains many unwanted frequency components, or harmonics, as shown in the left-side graph below. When entering the audio circuitry of an amplifier through the power supply, such harmonic components can interfere with the audio signal and cause intermodulation distortion which greatly affects sound quality. When passing through the PS-530, harmonics within the audible range are largely removed, and the result is a clean sine waveform

Strong power supply with high-efficiency toroidal transformer and large filtering capacitors

The PS-530 uses a massive toroidal type power transformer with high output capability. Rectification and smoothing is performed by two large aluminium electrolytic capacitors rated for 22,000 μF and built for high sound quality applications. This provides ample leeway.

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