● AC voltage stabilizer based on waveform shaping technology ● Acts as asource of extremely clean energy ● Low-distortion reference waveform generator● Highly effective waveform compensation ● Outstanding current capability● Superb interference rejection ● Built-in meter for monitoring vital parameters
including output power, input/output voltage, and input/output distortion ● Advanced
protection features ● Large high-efficiency toroidal transformer ● Eight AC outlets

The photograph shows the 230 V version.

Tap into a totally clean source of AC energy — Revolutionary waveform
shaping technology enables highly precise compensation, creating a pureenergy source of 230 V AC ±3 V (or 120 V AC ±1.5 V) with max. 0.1%
THD. Connect audio or video equipment for a drastic improvement insound and picture quality. Monitor output power (VA), input/output
voltage (V), and input/output distortion (%) on the built-in meter.
almost any high-quality A/V system currently on
the market.
All signal circuits of the PS-1220 are analog,
employing waveform shaping technology to turnthe power from a regular AC outlet into a highly
pure sine waveform for use as a stable anduncontaminated energy source for A/Vcomponents. To achieve this, the PS-1220 takes
the power source waveform and compares it to ahighly accurate and stable reference waveform.
Based on this comparison, it then adds orsubtracts exactly the required amount ofcorrection to create a clean output waveform. The
compensation required by this innovativetechnique typically is only a fraction of overall
power. The PS-1220 therefore operates with highefficiency and produces only a low amount ofheat. Since there are no oscillators or switches inthe signal lines, the PS-1220 itself does not act
as a source of spurious high-frequency noise.

The Clean Power Supply components fromAccuphase are revolutionary products thatremove noise and impurities from the AC powerline and improve signal quality by continuallymonitoring and shaping the power supplywaveform. They have been widely acclaimed for
drastically improving the sound and picture
quality of audio and video equipment. The
PS-1220 is an upgraded version that incorporates
latest MOS-FET push-pull differential drive
topology in the waveform compensation amplifiersection. The reference signal generator features
further improved accuracy and is linked to thepower section by a balanced connection toassure the lowest possible distortion in the output
waveform. The use of hospital grade AC outlets
and matched output impedance assure optimum
reliability. Because the PS-1220 can deliver as
much as 1200 VA (230 V AC version) or 1000 VA(120 V AC version), it covers the requirements ofPower Supply Waveform and Clean PS-1220 Output Waveform
Almost all electrical devices used in a household convert theAC supplied by the outlet into a DC current for poweringinternal circuits. This task is performed by a rectifier. As shownin photograph a, the rectifier load current has a pulse
waveform with a large current flowing momentarily in the vicinityof the voltage peak. This causes a voltage drop, resulting inclipping of the voltage waveform, as shown in photograph b. A
clipped waveform with a high amount of distortion contains
many unwanted frequency components, or harmonics, as
shown below. When entering the audio circuitry of an amplifier
through the power supply, such harmonic components caninterfere with the audio signal and cause intermodulation
distortion which has a highly detrimental effect on soundquality. When passing through the PS-1220, the deformed
waveform is restored to its original sine wave pattern (seefrequency spectrum in the graph below). The result is a cleansine waveform as shown in photograph c.
AC LINE POWER SPEC1〔dB〕
0.0
50Hz

−25.0

−50.0

−50.0

−75.0

−75.0

10k

20k〔Hz〕−100.00

10k

20k
〔Hz〕

Frequency spectrum of PS-1220 output (photo c)Frequency spectrum of power line (photo b)

Frequency spectrum of power line

Photo c PS-1220 output waveform(distortion approx. 0.06%)

MeterAlarm
indication
circuitMeter selector/
meter control switch

Switch position/
overload warning LEDs

Adding/subtracting
circuiteo
S1〜AC IN

S2

RectifierLinefilterOutputs

Error
detector
Waveformcomparator

Waveformcompensation amplifier

Voltage control circuitry
Reference
signal generator

Fig. 1 Operation Block Diagram of PS-1220

eiThe PS-1220 accepts AC power on the input side,processes it using internal control circuitry, and supplies itas clean AC power on the output side. Most of the ACenergy from the input is carried over to the output. The
loss introduced by the PS-1220 is very small, since itconsists only of the power required for waveformcompensation.
As shown in Figure 1, the signal from the secondary winding S1 of the transformer reaches the adding/subtracting
circuit and ap- Efficiency Input power
Load: pure resistancepears at the out- [%] 1800[VA]
put as output 80 1600
Efficiency
1400
voltage (e0). The
secondary wind- 60 1200
1000
ing S2 signal
40 800
Input/output power
goes to the refer600
ence waveform 20 400
generating circuit
200
where it becomes
0800
1000
1200
200
400600
Output power [VA]a high-precision
Output power/efficiency (input power) characteristics
sine waveform
Load: pure resistance
THD [%](ei) synchroni0.8
zed to the input
0.6
frequencyof
50/60 Hz. This
0.4
reference sine
wave (ei) is then
0.2
used as a reference signal to be
0200
400
600
800
1000
1200
Output power [VA]
compared to theOutput
power/THD
characteristics
output voltage.
The differentialFig. 2 PS-1220 Load Characteristics
component is extracted and used by the adding/subtracting circuit to provide exactly the required amount of compensation for turning the output into a high-precision sine waveform.

Highly Effective Interference Rejection
Photo b Voltage waveform of AC line
(distortion approx. 3%)

50Hz

−25.0

−100.00PS-1220 OUTPUT POWER SPEC1〔dB〕
0.0

Photo a Current waveform of rectified load

AC Voltage Stabilizer Based on Waveform Shaping Technology

The input side of the PS-1220 is equipped with aline filter for removing any high-frequency noisecomponents present in the power line, such asgenerated by digital equipment. The primary andsecondary windings of the power transformer are
kept totally separate, and the fully shielded design
shuts out any externally induced noise. Since theamplifier uses the feedback principle, output
impedance is extremely low. This prevents any
possibility of mutual interference between
components connected to the outputs of thePS-1220.

Built-in Meter Allows Easy Monitoring ofOutput Power (VA), Input/Output Voltage (V),and Input/Output Distortion (%). Overload
Indicated by Flashing LEDs.
The meter of the PS-1220 lets the user see at aglance how much power (VA) the connected
equipment is consuming at any given time. This isespecially helpful for components such as power
amplifiers whose power consumption differs
considerably depending on the volume. When themaximum rated output power (1200 VA for 230 V
AC version or 1000 VA for 120 V AC version) is
exceeded, the meter function selector LEDs flash
as a warning indication.

Compensation Amplifier Based on High-Precision Reference Signal Creates Pure 230 V (or 120 V) AC Source■Low-Distortion Reference Signal Generator

To generate the sine wave reference signal, the zero-cross point of the signal at
the S2 winding of the power transformer (see Fig. 1) is detected by an OP amp
and used by a high-precision Zener diode to generate a square waveform. A
newly developed 50/60 Hz bandpass filter and band-stop filter are 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 thesignal through another bandpass
filter, a low-distortion sine wave
(reference signal) is created thatis not dependent on the inputvoltage.

Assembly with reference signal generator and other circuitry〔50 Hz〕

Squarewavegenerator
Fromsecondary windingof power transformer

Bandpass
filter

Band-stop
filter
Bandpass
filter

Bandpass
filter〔60 Hz〕

Band-stop
filter

Reference
outputwaveform

Reference Signal Generator Block Diagram■Superior Waveform Compensating Power

When the input voltage is 220 V (110 V), the voltage at the secondary side of thetransformer will also be 220 V (110 V). To bring this to 230 V (120 V), 10 volts must
be added, as shown in Figure 2 (a). Conversely, if the input is 240 V (130 V), 10 volts
must be subtracted to yield 230 V (120 V), as shown in Figure 2 (b). (In actual operation, the peak value of 10 V, namely 14.1 V is added or subtracted.) The sine wave(ei) synchronized to the input frequency and the output voltage (eo) are compared,and for any excessive orPS-1220
missing component, a(230/120 V AC)
output waveformcompensation waveform
14.1V＋141V＋141V
240/130 V
up to a maximum of ±10 V
14.1VAC input waveform(peak value ±14.1 V) isPS-1220
220/120 V
230/120 V
generated and imposed
AC input
AC output
waveform
waveformon the output voltage.
00tt
Consequently, for aninput voltage range of
200-253 V AC (108-132 V
14.1V−141V−141V
14.1VAC) at the rated load of1000 VA (1200 VA), theoutput voltage is kept
Compensation
Compensation
waveform
waveform
constant at 230 V ±3 V＋14.1V＋14.1V
00tt(120 V ±1.5 V), with a−14.1V
maximum distortion ratio −14.1Vof 0.1%. These values(a) If power source voltage is(b) If power source voltage is higher
demonstrate the outlower than 230 V (120 V),
than 230 V (120 V), subtraction isaddition is performed
performed
standing waveform compensation ability of theWaveform Shaping Principle of PS-1220
PS-1220.
Assembly with output stage using 20-parallel push-pull power MOS-FETs mounted to two large heatsinks, waveform compensation amplifier for addition/subtraction, etc.

Excellent Current Capability
The power amplifier which performs waveform compensation uses the purecomplementary push-pull differential amplification principle for high raw gain,
outstanding accuracy, and excellent operation stability. The final stage employs
power MOS-FETs to reduce the load on the preceding stage and absorb sudden
load fluctuations with ease. The result is constant and stable power, with highperformance and ideal operation characteristics.
The power section is divided into two symmetrical parts with dedicated left andright heat sinks. Efficient cooling ensures stable operation for extended periods athigh power.
The output stage uses 20 power MOS-FETs rated for a maximum current of 10amperes. These devices are connected in a parallel complementary push-pullarrangement which boasts a rated output current of 12 A (8.3 A) and an
instantaneous peak current (inrush current) rating of 60 A
(120 A). This demonstrates the excellent
current capability of thePS-1220.

The photograph shows the230 V version.

t When the temperature of the internal heat sink or power

Multiple Protection Assures Total Operation Safety
If a problem should occur during operation, the circuit
breaker immediately shuts off the power to protect the unit
and any connected components from possible damage.
q When the combined load ofconnected equipment exceedsthe maximum rated output
power (1200 VA for 230 V AC
version or 1000 VA for 120 VAC version), the meter function
selector LEDs flash as awarning indication.

w When input current overload

Assembly with protection circuitry

occurs, the circuit protector
shuts off the power. Reduce the connected load and turn poweron again.

e 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, acurrent limiter becomes active to ensure safe use.

r When DC voltage is detected in the output due to anoperation problem or when the output voltage exceeds themaximum rating, the output is switched off to protect
connected components.

■ Front Panel

Strong Power Supply With High-Efficiency Toroidal
Transformer and Large Filtering Capacitors(47,000 μF ×2)
The power transformer plays a vital role in any power
supply. The PS-1220 uses a large toroidal type rated for1500 VA. Toroidal power transformers have large-gauge
copper wiring on a donut-shaped core, resulting in very
low impedance and high efficiency.

qToroidal transformer

Total of Eight AC Outlets
Eight AC outlets on the rear panel of the unit provide
ample capacity to connect for example a CD player,
preamplifier, power amplifier, and other A/V components,
up to the combined maximum rated power consumption(1200 VA for 230 V AC version or 1000 VA for 120 V ACversion). The low output impedance of each outlet meansthat all operate under the same conditions, so there will
be no difference in sound quality, regardless of which
outlet is chosen.
Meter of 120 VAC version★

(The photograph shows the 230 V version.)transformer becomes too high, the circuitry is automaticallyshut down.

Filtering capacitors

PS-1220 Meter (Power) Indication and LoadThe 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 is larger 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-1220 is the apparent power, the reading will behigher than the power consumption (W) given in catalogs and specification sheets.
● The rated power limit of the PS-1220 is 1200 VA for the 230 V AC version and 1000 VA forthe 120 V AC version. When deciding on equipment to be connected, select components
so that the total remains within these limits, and check actual power consumption using themeter.
● In case of overload, the meter function selector LEDs flash. Reduce the load by reducing
the number of connected components until the LEDs stop flashing and stay constantly lit.

ew

● The power consumption of integrated amplifiers and power amplifiers varies considerably
depending on the actual audio output. After connecting such equipment, perform playback
and verify that power consumption does not exceed the maximum rating when peaks in themusic are reproduced at high volume levels.

Output connectors of 120 V AC version■ Rear Panel★

(The photograph shows the 230 V version.) r

GUARANTEED SPECIFICATIONS
120 V version
Rated output capacity
Rated output voltage
Rated output current
Output frequency
Instantaneous peak current capacity
Output waveform THD
Rated input voltage
Input frequency
No-load power consumption
Cooling principle
Meter
VOLT-AMPERE

The usable power supply
voltage is indicated here.

qMeter (Output power, input/output voltage, input/output distortion)★
wPower switch/circuit protector
eMeter operation selector buttons
VOLT AMPERE (VA)★

t

AUTO MONITORr Output connectors (AC outlets)★
tAC power connector★

VOLTAGE INPUT/OUTPUT (V)DISTORTION INPUT/OUTPUT (%)

VOLTAGE INPUT/OUTPUT(green zone of scale)
DISTORTION INPUT/OUTPUT

AUTO-MONITOR

Maximum Dimensions
Mass

230 V version

1,000 VA (continuous)
1,200 VA (continuous)
120 V AC ±1.5 V
230 V AC ± 3 V
8.3 A
5.2 A
50 Hz or 60 Hz (identical to input frequency)
120 A
60 A
0.1% or less
120 V AC
230 V AC
50 Hz or 60 Hz60 W
Natural air cooling
0-1200 VA
The meter function selector LEDs flash when an overload occurs.
120 V AC ±5%230 V AC ± 5%0-6%Automatically switches meter from VOLT-AMPERE toDISTORTION OUTPUT in 4-second intervals
Width 465 mm(18-5/16")
Height 243.4 mm (9-9/16")
Depth 500.2 mm (19-11/16")
41.2 kg (90.8 lbs.) net
50.0 kg (110.2 lbs.) in shipping carton

Remark★ The 230 V AC and 120 V AC versions of the PS-1220 differ regarding meter voltage indication, AC output connector shape, supplied power cord, etc. Make sure that you have the correct version.

!
Caution＊The PS-1220 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-1220.
＊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-1220 with the above type of equipment.

Supplied accessories:• AC power cord

• Specifications and design subject to change without notice for improvements.

http://www.accuphase.com/

D1105Y PRINTED IN JAPAN 851-0203-00 (B1)