Studies On Residential Power Line Noise - Part 9 - PS Audio P5 AC Regenerator
The PS Audio Power Plant Premier (PPP) AC regenerator in my two channel system was replaced with a PS Audio PerfectWave P5 AC regenerator. Like many PPP owners, I was on the fence about "upgrading" from the PPP to the P5 because I wasn't sure the benefit, if any, would justify the expense. The P5 retails for $1305 more than the PPP ($3000 vs. $1695) and there are only minor differences in most of their performance specifications. Plus, the P5 has two less outlets than the PPP and the P5's continuous output power is 1/3 less than the PPP. It would seem like you are paying more for less. However, the P5 offers important upgrades in energy storage and energy delivery over the PPP which translate to a much better stereophonic presentation. After the first day, I could hear that the cost premium was justified. There was significant improvement in stereophonic performance parameters: more image weight, more depth, more bass weight and articulation and more fine detail.
The significantly lowered output impedance is important because it directly affects transient performance. Music signals have many peak power demands (transients) that last for only a small fraction of a second. The ability to cleanly and accurately reproduce such transients, particularly low frequency transients, contributes to the realism of sterophonic music reproduction.
Figure 1. The P5 is shipped double-boxed. The inner box contains an upper and
lower corrugated cardboard frame that surrounds and suspends the P5 in a tough
Figure 2. Sleek and elegant! The fit and finish of the P5 was excellent.
The PPP's case rang like a church bell. The P5's case is much better damped. Knocking on the P5's case in every location except for the upper side panels produced a solid dull thud. Knocking on the upper side panels produced a hollow sound.
Figure 3. P5 Rear. I didn't like the sideways turned outlets. Having to reach behind the unit and twist the
connectors of thick, stiff (1" diameter) power cables sideways was not fun.
The P5's user interfaces are the remote control, the front panel touch-screen and the online GlobalNet interface. The touch-screen provides a variety of menus for status reporting and control. I like the oscilloscope function that shows the input waveform, output waveform and the noise difference between the two.
Figure 4. P5's Home Screen.
Figure 5. P5's Status screen.
Figure 6. P5 Voltage Out Waveform screen.
There were two errors in the P5 manual (which must be downloaded from the PS Audio website):
Page 7: "Naming output receptacle #1, Zone A: By selecting the green "setup" button next to that zone, the screen will change to a keyboard interface upon which letters and numbers can be touched to name that zone. Generally, users of the Power Plant 5 will name said output receptacle by that which is connected. For example "DAC" or "Power Amp" or "Turntable"."
CORRECTION: Output receptacles can only be named through the online GlobalNet interface. PS Audio said the keyboard interface will be activated in a future firmware update.
Page 10: "After its activation, but before the P5 fully initializes and enters the HOME SCREEN, the unit?s front-panel touch-screen can be touched anywhere on its face. This will bring the user to the SYSTEM SETUP SCREEN where the following parameters are displayed:
1. Unit ID
4. Power Meter
CORRECTION: The System Setup Screen can only be accessed by touching the PS Audio logo in the center of the touch-screen as the P5 is initializing.
Figure 7. P5 and the PPP it replaced.
My initial plan was to move the PPP to my test rig. Apparently, the PPP did not appreciate being demoted to test rig duty. Immediately after turning on the PPP in its new location, it went into protection mode (as evidenced by a slow clicking sound). I rebooted the PPP and it went right back into protection mode. It was sent back to PS Audio for repair, which they did free of charge even though the unit was out of warranty. I had not had any trouble with it during the over three years it had been in my two channel system.
Three of the four PPP's I own have had to go back to PS Audio for repair. In each case there was a component failure in the regenerator circuit.
Figure 8. P5 installation in two channel equipment cabinet.
Figure 9. P5 installation in two channel equipment cabinet.
Online GlobalNet Interface
After a P5 is registered on the PS Audio website, the owner is able to monitor status and control certain functions through a web page interface. Individual power zones, as well as the entire unit, can be turned on and off remotely over the web interface. I (and other P5 owners) questioned the frequent voltage surges that appeared in the output voltage measurements. PS Audio confirmed that the voltage spikes shown in figure 10 are due to a bug in the P5's firmware. A firmware update to correct the bug is in progress.
Figure 10. P5 voltage vs. time report from web interface.
Subjective and Quantitative Discussion
Break In Procedure
At the time of this review, my two channel system consisted of:
Pass Labs X0.2 Line Level Preamp,
Pass Labs Xono Phono Preamp,
Cary Audio CD 306 Pro SACD Player,
Teres Audio Model 255 Turntable,
Graham Phantom B44 Tonearm,
Ortofon MC Windfeld Phono Cartridge,
Parasound Halo JC 1 Monoblock Power Amps,
Polk Audio SDA SRS 1.2TL speakers (4 Ohms Nominal Impedance, Highly Modified),
AudioQuest Sky XLR Interconnects,
AudioQuest Everest Speaker Cables,
AudioQuest LeoPard Tonearm Cable,
Salamander Synergy Triple 30 Audio Cabinet,
PS Audio AC-12 Power Amp and P5 Power Cables,
PS Audio Premier SC Source Component Power Cables.
The JC 1's are on separate dedicated 20 amp AC circuits terminated with PS Audio Soloist Premier SE in-wall conditioners. The P5 is also on its own dedicated 20 amp circuit terminated with a PS Audio Soloist Premier SE.
Only the preamps and source components are connected to the P5. The P5 cannot handle the current demands of even one JC 1 power amp. Plugging in the right side JC 1 caused the sound stage to collapse with a loss of speed, detail and articulation in the bass. Plugging in the left side JC 1 caused the P5 to go into protection mode and shut down.
I let the P5 warm up for 24 hours prior to installation. During warm-up time, I checked all functions and measured the input and output voltages with an oscilloscope and a multimeter.
The sonic improvements with the Power Plant Premier were evident immediately after installation. In contrast, the initial sound of the P5 was ugly and veiled. Sound stage width shrank to the vertical midpoint of each speaker. The rhythm and pace of music was slower. Bass was less defined and less articulate ("wooly" but not "muddy"). After five hours, the P5 "loosened up" and the sound became the equal of the PPP. After eight hours, I began hearing more image weight and ambient information compared to the PPP. There was also more depth and image definition, especially on orchestral recordings.
After an additional 30 hours under load, I began hearing more bass slam, bass articulation and more overall detail.
The two channel system's preamps and source components only offered a 14% load to the P5 (1.2 Amps, 108 watts). I ran the P5 at 14% load for the first 39 hours. For a more thorough and efficient break in process, I added secondary components to increase the reactive load as follows:
Yamaha C-80 Preamp
Sony ST-S730ES Tuner
Adcom GFA-5500 Power Amp
Polk Audio CRS+ Speakers (4 Ohms Nominal Impedance, Highly Modified)
The additional components increased the load to 41% (3.46 Amps, 289 watts). After 95 hours at 41% load, I added a second Adcom GFA-5500 Power Amp, which was left idling. This increased the load to 60% (4.95 Amps, 400 watts). During normal listening hours I would listen to music through the two channel system. Overnight and while at work, I let the tuner play through the secondary system.
I use a home made simple test and conditioning rig for power cables and AC receptacles (the Juice Cyclone). It consists of a long board with three incandescent light bulb receptacles connected in parallel. The receptacles are independently switched. More details on the Juice Cyclone can be found here: JuiceCyclone Power Cable Conditioner
Connecting the Juice Cyclone to the P5 with two 200 watt bulbs increased the load to 89% (7.5 Amps, 788 watts). This was with all audio components idling. If I played music, the load increased to 90% and the yellow (not orange as the manual states) warning symbol came on at the top of the Home Screen. Adding an additional 100 watt bulb increased the load to 98% (8.21 Amps, 888 watts).
I was impressed with the stability of the P5's power quality and with the stability of sound quality as the load increased. I heard no change in sound quality among the 14%, 40%, 60% and 90% load conditions. This was while the speakers were outputting an average 90 dB-C for hours. After 1 hour at 98%, I heard an overall loss of detail and smearing of bass. Reducing the load to 90% immediately returned the sound to normal.
The output total harmonic distortion was stable, between 0.2% and 0.3% as the load ranged from 14% to 98%. Most of the time it was 0.2%, even under the 98% load condition.
The P5 displayed excellent thermal stability. At a load of 40% or below, the P5 ran cooler than my Pass Labs X0.2 line level preamp. After 2 hours at 40% load playing music at an average 90 dB-C, the case top temperature of the X0.2 preamp was 92.7 degrees F. The P5's temperature (measured with a digital thermometer laid on the amplifier circuit vents) was 88.7 degrees F. After 4 hours at 60% load, the P5's temperature was 94 degrees F. After 12 hours at 90% load, the temperature was 102 degrees F. After 1 hour at 98% load, the temperature was 105 degrees F.
The fan is whisper quiet. Even from 6" away I only heard a faint hum rather than the familiar "whoosh". I could not hear the fan from 3 feet away.
The sonic changes throughout the burn in process are summarized in table 2.
Summary of Audible Improvements [Note: I listen mostly to instrumental jazz recordings.]
1. The P5 is as big a difference in sound quality over the PPP as the PPP was over the wall.
2. Sound stage depth increased, but not width.
3. More image weight and clarity, especially at the sound stage sides.
4. Much higher quality bass reproduction: more slam, detail, clarity, articulation and speed.
5. More of a sense of holographic 3-dimensionality.
6. More fluidity in mid-range and high frequencies.
7. More fine details, particularly ambient noises reflected from the recording space walls.
8. More tactile sensation against my body and more bass vibrations coming through the floor, armrests and seat.
The P5 uses a small size (5mm x 20mm) 5 amp slow blow fuse. After 125 hours, I replaced the P5's fuse with a HiFi Tuning Supreme fuse and I heard more fine details such as singer breathing noises, reed and mouthpiece noises, ambient room reflections and piano and bass note overtones and decay.
Under no load conditions, the output total harmonic distortion went from a steady 0.2% to fluctuating between 0.1% and 0.2% after the Supreme fuse was installed.
Curiously, the P5's fuse sounded best when oriented in the "wrong" direction (fuse arrow pointing against the direction of current flow). Other P5 and P10 owners have had the same results.
AC waveform and noise spectrum (Fast Fourier Transform) measurements were taken with a Tektronix 2012 digital oscilloscope after the 324 hour burn in process. The P5 plots in figures 13 and 16 are with a HiFi Tuning Supreme fuse installed. The time domain (sine wave) plots of the PPP and P5 are identical. It is easier to see the difference between the regenerator and wall sine waves and the differences between the regenerator and wall FFT plots if the plots are downloaded and viewed in succession.
The noise amplitude and density in the outputs of both regenerators was significantly less than the wall. The P5 demonstrated a moderate reduction in noise amplitude and density compared to the PPP. The P5's output also had less DC content (2 dB less).
Figure 11. AC sine wave from end of PerfectWave AC power cable plugged into a Soloist SE Premier
in-wall conditioner on a dedicated 20 amp AC circuit.
Figure 12. AC sine wave from output of Power Plant Premier.
Figure 13. AC sine wave from P5.
Figure 14. FFT plot from end of PerfectWave AC power cable plugged into a Soloist SE Premier
in-wall conditioner on a dedicated 20 amp AC circuit.
Figure 15. FFT plot from output of Power Plant Premier.
Figure 16. FFT plot from output of P5.
The next two plots show the difference in P5 output noise spectrum with the stock and HiFi Tuning Fuses installed. There was a moderate reduction in noise amplitude and density with the HiFi Tuning fuse. The DC content in the output also dropped by 2 dB with the HiFi tuning fuse.
Figure 17. Post burn in P5 output FFT plot with stock fuse.
Figure 18. Post burn in P5 output FFT plot with HiFi Tuning Supreme fuse.