●AC voltage stabilizer based on waveform shaping technology ● Supplies up to 510 VA of extremely clean energy ● Low-distortion reference waveformgenerator ● Highly effective waveform compensation ● Outstanding current
capability ● Superb interference rejection ● Built-in meter for monitoring vital
parameters: output power, input/output voltage, input/output distortion● Sophisticated protection features ● Large, high-efficiency toroidal transformer

The photograph shows the 230 V version.

Solve power supply problems once and for all — Revolutionary waveform
shaping technology made even more precise, to create a pure energy
source of up to 510 VA, rated for 120 V ±1.5 V/230 V ±3 V with max. 0.1%
THD. Connect audio or video equipment for a drastic improvement insound and picture quality. Visually monitor the quality and efficiency ofthe power source using the built-in meter with AUTO-MONITOR function.

AC Voltage Stabilizer Based on Waveform Shaping Technology
The PS-520 accepts AC power on the input side, processes it withinternal control circuitry, and supplies it as clean AC power on the
output side. Mostof the AC energy
Load: purely resistive
from the input is
Efficiency
carried over to the
output. The introduced loss consists
Input/output power
only of the power
required for waveform compensation.
0
100
200
300
400
500
As shown in Figure
1, the signal from
Output power/input power (efficiency) characteristics
the secondary windLoad: purely resistive
0.8
ing S1 of the transformer reaches the
0.6
adding/subtracting
circuit and appears
0.4
at the output as
0.2
outputvoltagee0. The second0
100
200
300
400
500
ary winding S2
Output power/THD characteristics
signal from thePS-520 Load Characteristics
transformer goesto the reference
waveform generating circuit where it becomes a high-precision sine
waveform ei synchronized to the input frequency of 50/60 Hz. Thisreference sine wave ei is then used as reference signal to be compared to the output voltage. The differential component is extracted
and used by the adding/subtracting circuit to provide exactly therequired amount of compensation for turning the output into a highprecision waveform.
Efficiency Input power
[%]
[VA]

Output power [VA]

THD
[%]

Output power [VA]

Superb Interference Rejection
The input side of the PS-520 is equipped with a line
filter, an isolation transformer with shielding between

Function buttons and LED indicators

The diagram shows the 230 V AC version
Meter
Measurement circuit transformer

Meter switching circuit
Measurement circuit

Waveform
after filtering

Before waveform shaping
Output waveform

Large filtering
capacitors

Secondary
RectifierS2〜AC IN

Before waveform shaping

Figure 1 PS-520 Operation Block Diagram
the primary and secondary side, and a high-speed
adding and subtracting circuit. This thorough,three-stage approach reliably removes any
high-frequency noise components present in the
power line, such as generated by digital equipment.
The output impedance of the amplifier section isextremely low, which minimizes the risk of mutualinterference between components connected to the
outputs of the PS-520.

OUTPUTS

Adding/subtracting
circuit

Reference
signalgenerator

Hum blocker

Inrush current
protection

PrimaryeoProtection
circuitS1

DC/AC detection
Temperature detection
Current detection

Input waveform withnoise and distortion

Isolationtransformer

Circuitprotector

Line filter

The Clean Power Supply components from Accuphase are
the result of intensive research into every aspect of powering
demanding equipment from the AC grid. They are designed toensure ideal conditions without compromise. Noise andimpurities are removed from the AC power line and signal
quality is improved by continually monitoring and shaping thepower supply waveform in real time. Revolutionary high-speed
circuitry adds or subtracts exactly the required amount ofcompensation, thereby minimizing distortion and creating aperfect waveform. The result is a drastic improvement in thesound and picture quality of audio and video equipment.
The PS-520 features a differential push-pull arrangement of
power MOS-FETs for the waveform compensation amplifier,which further improves the precision of the reference signal
and thereby the sound quality and performance of the power
supply. Balanced transmission is used for the link to the power
section, resulting in a cleaner output waveform with minimal
distortion. The use of high-quality AC outlets meeting exacting
standards with regard to electrical safety, and impedance
matching of all outlets means greatly improved reliability. All
circuitry in the PS-520 is analog. The power source waveform
containing noise and distortion is compared to a highly
accurate and stable reference waveform. Based on thiscomparison, the PS-520 then adds or subtracts exactly therequired amount of correction to create a clean power supply.
The required compensation typically is only a fraction of
overall power, which allows the PS-520 to operate with highefficiency while producing little heat. Since there are no
oscillators or switches, the PS-520 itself does not act as asource of spurious high-frequency noise.

Balancedtransmission

Error
detectorei
Waveformcomparator

Reference waveform

Waveformcompensation amplifier differential component

Waveform control circuit

Reference waveform

Assembly with input voltage/distortion monitoring circuitry Meter scale of 230 V AC version

The meter also lets the user see at a glance how much
power (VA) the connected equipment is consuming at any
given time, which is especially helpful for components
such as power amplifiers whose power consumption
differs considerably depending on the actual volume.
An AUTO-MONITOR function that automatically switches
the meter indication is also provided.

Built-in Meter Allows Easy Monitoring of
Output Power (VA), Input/Output Voltage (V),
Input/Output Distortion (%). Excessive Load
Indicated by Flashing LEDs.
The constantly fluctuating voltage and distortion at aregular household AC outlet can be monitored in real time.

Power Supply Waveform and Clean PS-520 Output Waveform
Almost all electrical devices used in a household convert the AC supplied by theoutlet into a DC current for powering internal circuits. This task is performed by arectifier consisting of a combination of diodes and capacitors. The rectifier load
current has a pulse characteristic with a large current flowing momentarily in thevicinity of the peak of the voltage waveform (sine waveform). The resistance ofelectrical in-wall wiring and power cords affects the waveform and leads to a drop involtage, which is seen as clipped waveform with higher amounts of distortion. The
clipped waveform results in less power being available, so that connected equipment Photo (a) Current waveform of rectified load
does not receive enough energy to develop its full potential. The distorted waveform
also contains many unwanted frequency components, or harmonics. When entering
the audio circuitry of an amplifier through the power supply, such harmoniccomponents can interfere with the audio signal and cause intermodulation distortion
which has a highly detrimental effect on sound quality. The AC power therefore not
only is subject to noise and distortion while being delivered to the load, it is thenfurther degraded in the equipment itself through the process of power consumption.
When passing through the PS-520, practically all unwanted harmonics components
in the audible range are removed (see frequency spectrum in the graph below), andthe waveform is restored to its original sine wave pattern as shown in photograph (c). Photo (b) Voltage waveform of AC line
(distortion approx. 3%)

〔dB〕
0.0

〔dB〕
0.0

AC Line Power Spectrum 1
50Hz

−20.0

−20.0

−40.0

−40.0

−60.0

−60.0

−80.0

−80.0

−100.0−100.0−120.0
0

10k

20k
〔Hz〕

Frequency spectrum of power line (photo b)

PS-520 Output Power Spectrum 1
50Hz−120.0
0

10k

20k
〔Hz〕

Frequency spectrum of PS-520 output (photo c)Frequency spectrum of power line

Photo (c) PS-520 output waveform(distortion approx. 0.06%)

The photograph shows
the 230 V version.

▲

Clean internallayout designed
for optimal
power andsignal flow▲

Distortion scale(%)

Assembly with 10 parallelpush-pull power MOS-FETs
mounted to large heat sink,waveform compensation amplifier
for addition/subtraction, etc.

Volt-Ampere scale(VA)
Voltage scale (V)Outstanding Current Capability
The power amplifier which performs addition/subtraction for waveform compensation uses thepure complementary push-pull differential principle for high gain, excellent precision, andcomplete operation stability. In the output stage, a 10-parallel complementary arrangement (10P channel pairs, 10 N channel pairs) of power MOS-FETs rated for max. 30 A is used. This
reduces the load of the preceding stage and reliably absorbs even rapid load fluctuations,providing a rated output current of 2.2 A (4.2 A), with an instantaneous peak current (inrush
current) rating of 30 A (60 A). This demonstrates the excellent current capability of the PS-520.

Compensation Amplifier Based on High-Precision Reference Signal Creates Pure 230 V (or 120 V) AC Source■Superior Waveform Compensating Power■Low-Distortion Reference Signal Generator
In the PS-520, the power supply output frequency is matched to the input frequency
without the use of an oscillator that can become a source of noise and interference.
The zero-cross point of the signal at the S2 winding of the power transformer (see Fig.
1) is detected and used as AC voltage sine wave reference to generate a highly
accurate square waveform. A newly developed 50/60 Hz band-pass filter andband-stop filter is then applied to
the waveform. 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, alow-distortion sine wave (reference
signal) is created that is notdependent on the input voltage.

Assembly with reference signal generator and other circuitry

Power supply
input waveform

Reference sine
waveform

Square wave

〔50Hz〕

Band-passfilter

Band-stop
filterSquare wave

From secondary generator
winding of powertransformer

Band-passfilter
Band-passfilter〔60Hz〕

Band-stop
filter

Reference Signal Generator Block Diagram

Reference output
waveform

The waveform compensation capability of the PS-520 not only eliminates noise and distortion, it
also deals with sudden and rapid voltage fluctuations in real time. When the input voltage is
110/220 V, the voltage at the secondary side of the transformer will also be 110/220 V. To bringthis to 120/230 V, 10 volts
must be added, as shown
PS-520 120/230 V AC
output waveform
14.1V
in Figure (a). Conversely, ＋170V/＋170V/
14.1 V
130/240 V AC input
325V
325V
if the input is 130/240 V,
waveform
10 volts must be subPS-520
110/220 V AC
110/220 V AC
tracted to yield 120/230 V.
input waveform
output waveform
00tt(As the figures show, in
actual operation, the peakvoltage of 120/230 V is
14.1V
−170V/
170/325 V, and the peak −170V/
14.1V
325V
325V
value of 10 V, namely
14.1 V, is added or subCompensation
Compensation
tracted.) The sine wave
waveform
waveform＋14.1V＋14.1V(ei) synchronized to the00tt−14.1V−14.1V
input frequency and theoutput voltage (e0) arecompared, and for any(a) If power source voltage is lower than(b) If power source voltage is higher than
120 V/230 V, addition is performed
120 V/230 V, subtraction is performed
excessive or missing
component, a compensaWaveform Shaping Principle of PS-520
tion waveform up to a
maximum of ±10 V (peakvalue ±14.1 V) is generated and imposed on the output voltage. Consequently, for an input voltage range of 108 V - 132 V/207 V - 253 V at the rated load of 510 VA , the output voltage is kept
constant at 120 V ±1.5 V/230 V ±3 V, with a maximum distortion ratio of 0.1% . These values
demonstrate the outstanding waveform compensation ability of the PS-520.

Sophisticated Protection Features

Strong Power Supply With Massive High-Efficiency Toroidal Transformer and Large Filtering Capacitors

All operation factors including voltage, current, power, DC
components, temperature etc. are constantly monitored, forreliable protection in case of any problem.

The power transformer, a crucial component, is amassive toroidal type. Toroidal power transformers
employ large-gauge copper wiring on a donut-shaped
core, which creates a smooth and closed magnetic
path with minimal external leakage. The result is
extremely low impedance and high efficiency. Two
specially designed high-quality 22,000 μF filtering
capacitors selected for outstanding sound provide
ample smoothing capacity.

z When the combined
load of connected
equipment exceeds the
maximum rated output
power of 510 VA, theindicator LEDs of themeter selector buttons
flash as a warning
indication.
x When input current
Assembly with protection circuitry
overload occurs, thecircuit protector shuts off the power. Reduce the connected load andturn power on again.
c In case of momentary power overload such as caused byinrush current when a component is switched on or when apower amplifier reproduces a peak passage in the music, a30/60 A current limiter becomes active to ensure safe use.
v Internal operation is monitored constantly. When a problem
such as DC voltage in the output or output voltage exceeding
the maximum rating is detected, the output is switched off
instantly to protect connected components.
b When the temperature of the internal heat sink or powertransformer is very high for an extended period, the circuitry is
automatically shut down.

The six (for 230 V) or eight (for 120 V) AC outlets of the PS-520 are high-quality types. Internal
circuitry makes ample use of gold-plated parts and customized parts. The circuit protectors are
quality devices that react with higher speed than conventional circuit breakers. Vibration-damping
rubber parts are used for mounting. This attention to detail is evident throughout the PS-520.

Line filter, vibration-damping rubber, circuit protector

Meter of 120 V AC version■ Front panel(The photograph shows the 230 V version.)q

Filtering capacitors

High-Performance Parts Selected for Sound Quality

Parts selected for high sound quality and high reliability

PS-520 Meter (Power) Indication and Load★

The power consumption of electrical equipment, as indicated on the equipment itself and in catalogs
and other documentation according to legal requirements, is usually given in watts (W). This figure
represents the so-called effective power. However, the actual power drawn by the equipment islarger than the effective power. This is called the apparent power which is calculated by multiplying
the applied voltage (230 V or 120 V) with the actual current. The unit for apparent power is VA(Volt-Ampere). Since the value shown by the meter of the PS-520 is the apparent power, thereading will be higher than the power consumption (W) given in catalogs and specification sheets.
● The rated power limit of the PS-520 is 510 VA. When deciding on equipment to beew

Output connectors of 120 V AC version■ Rear panel(The photograph shows the 230 V version.)r★

connected, select components so that the total remains within this limit, and check
actual power consumption using the meter.
● High-output class-A power amplifiers, such as the A-65, which constantly draw a highidling current when switched on cannot be connected to the PS-520.
● In case of overload, the indicator LEDs of the meter operation selector buttons flash. Reduce the load by
reducing the number of connected components until the indicator LEDs stop flashing and stay constantly lit.
● The power consumption of integrated amplifiers and power amplifiers varies considerably depending on theactual audio output. After connecting such equipment, perform playback and verify that the meter indication
does not exceed 510 VA also at the highest volume level setting.

PS-520 GUARANTEED SPECIFICATIONS
120 V version
Rated output capacity
Rated output voltage
Rated output current
Output frequency
Instantaneous peak current capacity

The usable power supply
voltage is indicated here.

t★

r Output connectors
q Meter(AC outlets)★
(Output power, input/output voltage, input/output distortion)★
w Power switch/Circuit protectort AC power connector ★
e Meter operation selector buttons
VOLT-AMPERE (VA) VOLTAGE INPUT/OUTPUT (V)DISTORTION INPUT/OUTPUT (%) AUTO-MONITOR

Output waveform THD
Rated input voltage
Input frequency
No-load power consumption
Cooling principle
Meter
VOLT-AMPERE
VOLTAGE INPUT/OUTPUT(green zone of scale)
DISTORTION INPUT/OUTPUT
AUTO MONITOR
Maximum Dimensions

230 V version

510 VA (continuous)
120 V AC ±1.5 V
230 V AC ±3.0 V
4.2 A
2.2 A
50 Hz or 60 Hz (identical to input frequency)
60 A
30 A
0.1% or less
120 V AC
230 V AC
50 Hz or 60 Hz
50 W
Natural air cooling* In case of overload, the indicator LEDs of the meter selector buttons flash.
0-510 VA
120 V AC ±5%230 V AC ±5%

0-6%
Cycles through VOLT-AMPERE -- DISTORTIONDISTORTION OUTPUT indication in 4-second intervals
Width 465 mm (18-5/16")
Height 181 mm (7-1/8")
Depth 386 mm (15-3/16")

24.1 kg (53.1 lbs.) net
23.5 kg (51.8 lbs.) net
Mass
30.0 kg (66.1 lbs.) in shipping carton 30.0 kg (66.1 lbs.) in shipping carton
Remark★ The 230 V AC and 120 V AC versions of the PS-520 differ regarding meter voltage indication, AC output connector shape, supplied power cord, etc. Make sure that you have the correct version.

Caution＊The PS-520 is available in 230 V AC and 120 V AC versions. The actual allowable voltage is indicated next to the AC power connectors on the rear panel. Be sure to check thisindication before using the PS-520.
＊This product can be used only on a regular household AC circuit rated for 230 V or 120 V AC, 50/60 Hz. Using the product with portable AC generators, airplane or ship power
generators or other types of power sources is not possible.
＊This product is designed to improve the quality of AC power supplied to audio or video components. Do not use it to power industrial type equipment or common household electricalappliances.
＊Do not use this unit for powering equipment where failure incurs a risk of injury or fatal accidents (medical equipment, aviation equipment, traffic control equipment, furnace and heating
control equipment, safety devices, etc.). Accuphase will not be liable for any problem occurring due to use of the PS-520 with the above type of equipment.

Supplied accessories:• AC power cord 2 m• Specifications and design subject to change without notice for improvements.

http://www.accuphase.com/

D1205Y PRINTED IN JAPAN 851-0213-00 (B1)