Accuphase PS-1220 User Manual
● AC voltage stabilizer based on waveform shaping technology ● Acts as a
source 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 pure
energy 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 in
sound and picture quality. Monitor output power (VA), input/output
voltage (V), and input/output distortion (%) on the built-in meter.
The Clean Power Supply components from
Accuphase are revolutionary products that
remove noise and impurities from the AC power
line and improve signal quality by continually
monitoring and shaping the power supply
waveform. 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 amplifier section. The reference
signal generator features further improved
accuracy and is linked to the power section by a
balanced connection to assure the lowest
possible distortion in the output waveform.
Furthermore, the matched output impedance
assures 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 of 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 turn
the power from a regular AC outlet into a highly
pure sine waveform for use as a stable and
uncontaminated energy source for A/V
components. To achieve this, the PS-1220 takes
the power source waveform and compares it to a
highly accurate and stable reference waveform.
Based on this comparison, it then adds or
subtracts exactly the required amount of
correction to create a clean output waveform.
The compensation required by this innovative
technique typically is only a fraction of overall
power. The PS-1220 therefore operates with
high efficiency and produces only a low amount
of heat. Since there are no oscillators or switches
in the signal lines, the PS-1220 itself does not
act as a source of spurious high-frequency noise.
Power Supply Waveform and Clean PS-1220 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. As shown
in photograph a, 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, 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 can
interfere with the audio signal and cause intermodulation
distortion which has a highly detrimental effect on sound
quality. When passing through the PS-1220, the deformed
waveform is restored to its original sine wave pattern (see
frequency spectrum in the graph below). The result is a clean
sine waveform as shown in photograph c.
PS-1220 OUTPUT POWER SPEC1
〔Hz〕
〔dB〕
0.0
50Hz
−
25.0
−
50.0
−
75.0
−
100.0
0 10k 20k
FrequencyspectrumofPS-1220output(photoc)
Meter selector/
meter control switch
S1
S2
Rectifier
Reference
signal generator
〔dB〕
AC LINE POWER SPEC1
0.0
50Hz
−
25.0
−
50.0
−
75.0
−
100.0
0 10k 20k
Frequencyspectrumofpowerline(photob)
〜AC IN
Frequencyspectrumofpowerline
Line
filter
Photo a Curre nt wav eform of rec tified load
PhotobVoltagewaveformofACline
(distortionapprox.3%)
〔Hz〕
PhotocPS-1220outputwaveform
(distortionapprox.0.06%)
Alarm
circuit
indication
circuit
Adding/
subtracting
Error
Waveform
comparator
detector
Voltagecontrolcircuitry
e
i
Meter
Switch position/
overload warning LEDs
e
o
Outputs
Waveform
compensation amplifier
AC Voltage Stabilizer Based on Waveform Shaping Technology
The PS-1220 accepts AC power on the input side,
processes it using internal control circuitry, and supplies it
as clean AC power on the output side. Most of the AC
energy from the input is carried over to the output. The
loss introduced by the PS-1220 is very small, since it
consists only of the power required for waveform
compensation.
As shown in Figure 1, the signal from the secondary winding S1 of the transformer reaches the adding/subtracting
circuit and appears at the output as output
voltage (e0).
The
secondary winding S2 signal
goes to the reference waveform
generating circuit
where it becomes
a high-precision
sine waveform
(ei) synchronized to the in put
frequency of
50/60 Hz. This
reference sine
wave (ei) is then
used as a reference signal to be
compared to the
output voltage.
The differential
component is ex-
Input power
Efficiency
[VA]
[%]
1800
80
1600
1400
60
1200
1000
40
800
600
20
400
200
0
Output power/efficiency (input power) characteristics
THD[%]
0.8
0.6
0.4
0.2
Output power/THD characteristics
Fig. 2 PS-1220 Load Characteristics
400 600200
400 6002000
Load: pure resistance
Efficiency
Input/output power
Load: pure resistance
800 1000 1200
Output power [VA]
800 1000 1200
Output power [VA]
tracted 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
The input side of the PS-1220 is equipped with a
line filter for removing any high-frequency noise
components present in the power line, such as
generated by digital equipment. The primary and
secondary windings of the power transformer are
kept totally separate, and the fully shielded design
shuts out any externally induced noise. Since the
amplifier uses the feedback principle, output
impedance is extremely low. This prevents any
possibility of mutual interference between
components connected to the outputs of the
PS-1220.
Built-in Meter Allows Easy Monitoring of
Output 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 a
glance how much power (VA) the connected
equipment is consuming at any given time. This is
especially helpful for components such as power
amplifiers whose power consumption differs
considerably depending on the volume. When the
maximum 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.
Fig. 1 Operation Block Diagram of PS-1220
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