Double Takes! PS Audio P300 Power Plant

Double Takes!
PS Audio P300 Power Plant
Frank (Ace) Alles & Noel (Too-Keen) Keen
25 August 1999


PS Audio Power Plant P300
Price: $995 US plus shipping ($1,245, 230 volt model, plus shipping and duties)
Manufacturer: PS Audio Service Center, 8793 F. Plata Lane, Atascadero, CA. 93422
Tel: 877-772-8340; fax: 303-543-7200
Dimensions: 5.5 inches × 8.85 inches × 19 inches (H×W×D)
Weight: 30 pounds (40 pounds 230 volt model)

DoubleTakes! is a new column that will attempt to apply a Siskel & Ebert twist to audio reviewing. In this inaugural chapter, my partner, Too-Keen and I will examine an intriguing, reportedly ground-breaking new product in the area of AC power line purification. Will the PS Audio P300 Power Plant live up to the laudable goals that its venerable designer, Paul McGowan, has claimed for it? We shall see...

In keeping with the spirit of the whole S&E bucket of worms, I’ve established a new rating system based on 0 to 5 GOOSEBUMPS. The system may be interpreted as follows:

GooseEgg = Omelet Time, an underdeveloped concept!
One GooseBump = Gosling, largely sophomoric performance
Two GooseBumps = Blue Collar Goose, good mean-level performance
Three GooseBumps = White Collar Goose, above average, by a neck
Four GooseBumps = Goose hierarchy, among the best in its class
Five GooseBumps = Midas territory, the top of the heap!

In this episode of DoubleTakes, my esteemed colleague, Too-Keen, will have the first quack--er, word--and I (Ace) will ride shotgun. Let the festivities commence!

NTK Comments

"My listening notes cite things like greater resolution of detail, a greater sense of air around instruments/singers and tighter bass. Traces of digititis observed on some CD tracks without the P300 were reduced or eliminated with the power regenerator present."

The Power Plant P300 is a regenerative AC synthesizer. It removes various types of interference from common AC household power and is claimed to avoid some of the downsides of power line conditioners, such as increased output impedance and suppression of audio system dynamics. It protects against surges/spikes and solves the problem of excessively low or high line voltages, by providing a preset, fully regulated output voltage. The P300 (300 watts maximum output) is the first of four power plants to be released by PS Audio. Soon to be introduced are the P600, P1200 and P2000 (see the PS Audio Web page noted above for more information). PS Audio has recently been re-acquired by famed designer Paul McGowan, and the Power Plants are the first of a series of new products from the revitalized company. The Power Plants are being direct marketed and sold through dealers. Audiophiles may sign up on the PS Audio Web page to receive one of the direct marketed products.

Briefly, this is how it works: it transforms the incoming 120 volt (USA) or 220 (Europe) volt input to 143 volts, rectifies this to DC, filters this voltage and then amplifies it with class AB stages, using DSP controlled oscillators to reconstruct the AC sine wave to a precise 120 volt or 220 volt AC power source. Four high quality AC outlets are provided on the back of the P300 for your components. Claimed advantages of the Power Plants are:

  • Outputs a near perfect AC sine wave, free of the spikes and garbage inherent in household AC circuits, including radio frequency interference (RFI) and electro-magnetic induction (EMI).

  • Supplies stable fully regulated AC, immune to power line fluctuations.

  • Has essentially zero output impedance, unlike the case with any PLC.

  • Balanced power, with 57.5 volts each from two power amplifiers.

  • Permits varying the frequency of the output AC voltage from 50-120 Hz.

  • Provides spike and surge protection via multiple redundant 4500V MOV’s.

"The P300 arrived triple boxed and well packaged; the strongest UPS gorilla would have difficulty damaging it."

While the idea of AC power regeneration is not new (it is used in the Mark Levinson No. 33 amplifier, for instance), the PS Audio Power Plants are breakthrough stand-alone products and a promising approach to the conundrum of getting pure AC power to audio components. I used the P300 mainly with a Krell KPS 20-iL CD player and with a variety of power cords into and out of it. Overload protection shuts the P300 down if power draw exceeds 300 watts, so the device cannot be used with medium or high powered amplifiers.

The P300 arrived triple boxed and well packaged; the strongest UPS gorilla would have difficulty damaging it. Although relatively small in size, the P300 is surprisingly heavy, about 30 pounds, mainly due to two large power transformers inside. A comprehensive and well-written owner’s manual accompanied the unit. The P300 has an internal switch for converting from 115 to 220 volts input. Also, an internal ground jumper can be disconnected if the user decides to use an external earth ground, as strongly recommended by PS Audio (if you haven’t done this, do it!). Notwithstanding a rather thin and flimsy removable lower cover plate, the rest of the P300 is solidly built and the internal components appear to be of high quality. The P300 has a switchable front panel display that indicates the total wattage being consumed, or the frequency of the AC power being passed to its outlets. Two push buttons allow changing the frequency up or down between 50 and 120 Hz, in 5 Hz increments.

The P300 fired up immediately and worked perfectly in my system without glitches. Being the mischievous sort, I had to test the power maximum by plugging one of the KR Enterprise monoblock amps into the P300. The output wattage quickly ramped up to a displayed 310 watts and then, as advertised, the device promptly shut down. Upon unplugging the amp, the P300 immediately re-powered and worked perfectly. A consideration when using the Power Plants (more-so if you are contemplating the larger models with power amps) is the fact that the power regenerator consumes about 2 watts of AC power for every watt it passes on to your components. The difference, of course, heats your house and pays your power utility’s bonds. In my case, the Krell KPS 20-iL CD player consumed 80 watts at rest and 110 watts when playing. The P300 became warm when the CD player was running, but not excessively so, such that a hand could comfortably be placed on its top.


"Initially I had guessed that the P300 would do the same things some of the better power cords did, and predicted that the P300 might tend to bring all of the power cords (including the cheap stock cord to the CD player) up to the level of the best cords… they all just performed at a higher level when run from the P300"

After allowing the P300 to warm up for about 30 hours with the CD player plugged in, I made my initial listening observations. I did not notice significant changes in system sound with the P300 as a function of time, suggesting that it does not require substantial break in. Whether the CD player was plugged into a dedicated 20 amp wall circuit or into the Magnan Signature power cord/strip, it was immediately clear that the P300 provided improved sound. My listening notes cite things like greater resolution of detail, a greater sense of air around instruments/singers and tighter bass. Traces of digititis observed on some CD tracks without the P300 were reduced or eliminated with the power regenerator present. For instance, on track 6 of Muddy Waters’ Folk Singer CD (Mobile Fidelity UDCD 593), the P300 provided better resolution of strings and voice, better bass resolution, and improved the "air" or presence of the music by a substantial degree, as compared to plugging the player into a wall outlet. With Emmy Lou Harris’ Spyboy, track 9 (Eminent, EM-25001-2), the P300 eliminated a harshness on the cymbals, and tightened and better differentiated the bass. With the excellent Villa Lobos’ Everest track "Little Train of the Caipira" (EVC 9007), the P300 made a clear improvement in resolution, fidelity, three dimensionality and in the air surrounding instruments. While the improvements varied with the software, I concluded that the P300 improved all types of music.

Changing Power Cords

PS Audio strongly discourages using a PLC before or after their Power Plants, or using power cords that contain built-in filters. However, they do note that changing the power cords feeding the P300 may affect its sound character. In this, PS Audio is correct. I experimented with various combinations of the after-market power cords I had on hand and found that all of them improved system sound relative to the stock Belden type cord supplied with the P300. The Sahuaro SlipStream cord made a noticeable improvement, but the best of the lot was the Shunyata PowerSnakes King Cobra, a cord that performed so well on digital in my recent power cord trials. This cord did not affect total system dynamics appreciably, but it wove the same magic as when used as a power cord from the P300 to the CD player--namely, greater depth, presence, and life to the music with an enhanced sense of air around instruments and more realistic soundstaging.

Initially I had guessed that the P300 would do the same things some of the better power cords did, and predicted that the P300 might tend to bring all of the power cords (including the cheap stock cord to the CD player) up to the level of the best cords. While the performance of all cords was elevated to some degree, I was surprised that power cords generally exhibited the same sonic characteristics as they did when plugged directly into the wall--they all just performed at a higher level when run from the P300.

In fact with the exception of the cord run from the P300 to the Krell CD player, the other cords I tried yielded immediately perceptible differences as compared to the same cords plugged into a wall outlet. For instance, with the King Cobra cord, track 1 on Harvey Reid’s Chestnuts CD (Woodpecker, WP109CD), plugging the cord directly into a 20 amp dedicated wall outlet led to a tinny, less ambient sound on the 12 string guitar, imparting a more twangy character to the instrument. Running the CD player with a PowerSnakes King Cobra cord plugged into the P300 restored greater resolution, air and tonality to the strings on this track, and eliminated the twanginess and tinniness. Similarly the First Impression Music Reference II disc, track 15 (FIMCD 007) revealed that, when the CD player was plugged directly into the wall, the system showed reduced dynamics, with less air and ambience around instruments and poorer soundstaging. The excellent drum and cymbal work on this track lacked palpability and realism as compared to running the CD player with the PowerSnakes King Cobra plugged into the Power Plant P300. These differences were not subtle. They added up to a presentation that was eminently more musical with the P300 in the chain.

While fiscally silly to use $4000 retail worth of power cords into and out of a $1000 component, two PowerSnakes King Cobras used with the P300 was a magical combination. My experience reinforces the view of many audiophiles that high quality power cords should in fact be viewed as components. Indeed upgrading power cords may improve system sound more than spending $10,000 on a new CD player. Accordingly, purchasers of the P300 are advised to experiment with alternative power cords into and out of the P300. PS Audio sells an optional high performance AC cord designed specifically for use with the Power Plant, but alas, I did not test it here.

I use an Adcom GCD-600 CD player (5 disc carousel) when entertaining and connect its digital out to the Krell CD player’s DACs. For fun, I ran the Adcom CD player with its own DACs and connected it directly to the KR power amps. Then I could compare the sound quality with the CD player run from the wall or plugged into the P300 (the Adcom has a permanent power cord). While the sound quality was, of course, below that of the Krell CD player, I can say that the improvement with the P300 powering the Adcom player, relative to wall plugging, was greater than with the Krell. This is perhaps to be expected in view of the higher quality power supplies of the Krell product. Accordingly, I’d speculate that the P300 may provide greater relative benefits with lower priced components.

"I ended up liking 70-80 Hz the best since that pumped just a trace more life into most software. Certainly, the provision for changing output frequency is a real advantage."

On the Krell CD player, the effects of changing frequency output from the P300 were subtle but evident. When ramping the frequency up from the standard 60 Hz, the system became somewhat more dynamic and lively on most material. However, at the maximum 120 Hz output, things became thinner, with a bit of a tinny character on some software. On the other hand, reducing the output to 50 Hz (lowest allowable) seemed to produce a more mellow, damped system sound. So, what have we got here? Another tone control, that’s what--to be added to the repertoire of Black Diamond Racing Cones and Vibrapods, room treatments, power cords, speaker cables, etc. I ended up liking 70-80 Hz the best since that pumped just a trace more life into most software. Certainly, the provision for changing output frequency is a real advantage.


Since the ElectraGlide power cords woke many of us up some two years ago, audiophiles have generally come to appreciate that the quality of the AC power delivered to one’s system is a major factor in its sound quality. Certainly, the gremlins that infest residential power lines make a hostile environment for audio components. The PS Audio Power Plants are a clean and clever approach to removing most if not all of the incoming AC line garbage. They provide a closely regulated 120 watt (220 in Europe and some other places) output to components, as well as the added benefits of frequency adjustment and surge/spike protection. All of this would be for naught if the P300 did not improve sound—I am pleased to say, "Yes it does!" The PS Audio P300 offers several advantages over PLCs. Improved examples of its breed may appear, but for the moment the P300 can be viewed as a breakthrough product.

As to the coveted GooseBump rating, I give the P300 FOUR BIG GOOSEBUMPS on the grounds that there is room for improvement in even the best of products. This leaves a bit of latitude for rating competing products of this genre whenever they may emerge.


"Ace" Alles Comments

"The P300 performed flawlessly in my system with the exception that it emitted a slight mechanical hum. This is normal for this unit and was not particularly noticeable from my listening seat."

I thank my colleague, Too-Keen, for his informative prose and his considered observations of this first in a new breed of power line purification devices. Paul McGowan is to be congratulated for recognizing a void in the current marketplace and for designing a well conceptualized product line to fill that void.

The great thing about all the PS Power Plants is that unlike most power line conditioners which are most effective at filtering select frequency ranges, many of them outside the audio bandwidth, the Power Plants work to banish grunge and noise from the entire audio frequency spectrum and beyond.

Some P300 users have discovered that these devices are a splendid source of pure AC for running their AC synchronous turntable motors. Indeed, the more expensive Walker motor-drive, designed by Dan Fanny of AHT, works on the same principle though it has a lower power output and it can’t be used for powering multiple components.

For the 33.3 RPM speed the Power Factor (line frequency) must be set to the 60 Hz default setting. Some turntable manufacturers such as Walker, Basis, VPI and Rega make turntables with AC synchronous motors that are stable when used at a higher line frequency. This means that dialing in 80 Hz, or 81 Hz to be more precise, will result in an increase to the 45 RPM speed. However other turntables with synchronous motors that use a certain type of speed control circuitry could be damaged by prolonged operation above 80 Hz. Among these are Roksan, Merrill and others, which can still be operated safely at the 60 Hz setting. Of course turntables using DC and non-synchronous motors won’t be affected (and the speed won’t change) by altering the line frequency. Likewise CD players and transports should not be affected. When in doubt, ALWAYS consult the manufacturer.

In current P300 units, there is no way to set the Power Factor to exactly 81 Hz. Some users have found the 80 Hz setting to be close enough to suit them. The good news is that all Power Plants manufactured after October ‘99 will be programmable to 81 Hz, for exact 45 RPM turntable speed, though it won’t be fine-tunable like the Walker unit.

The P300 performed flawlessly in my system with the exception that it emitted a slight mechanical hum. This is normal for this unit and was not particularly noticeable from my listening seat.

Initially I tried using the P300 to power my Parasound 2000 series DAC and transport. Later I added my AHT tube line stage preamp. Even though the AHT has a robust, highly regulated power supply, the P300 still made a gratifying improvement.

With regard to changing the Power Factor I found myself rather amused by the results I obtained. With some settings the sound seemed a bit more etched than with others and I found that the images in the soundstage would climb the vertical plane of my InnerSound Eros speakers at some frequency settings. Curiously, at the 80 Hz position I, like Too-Keen, got very good results. The image settled closer to the ground and the precision of its focus was extraordinary.

The Sound

"Gershwin would have liked the PS P300 too, because it rendered the sprightly piano work on his Rhapsody In Blue from Dayful Of Song (Delos DE 3216) sharper with less rounding. Yet there was no hardness or stridency."

I am largely in agreement with my partner’s assessment of the sonic merits of the P300, but I would like to offer a slightly different perspective to you readers (natch!). On the subject of power cords, I also observed that the various cords I tried between the wall outlet and the P300 all sounded different. In addition to the stock cord I tried a Harmonic Technology cord, a Clayton Audio cord, a heavy-duty Belden cord and the stock black cord supplied by PS Audio.

I found that they did in fact all sound different and I dare say that I could hear the same respective character in these cords as I hear when they are plugged directly into the wall. Of course the P300 cleaned up the sound but their intrinsic sonic signature remained. Because each cord has its own set of inductive/capacitive and resonant characteristics, this was to be expected. It does not in any way invalidate the positive attributes of the Power Plant.

My initial impression of the P300 was that individual instruments and vocalists were more precisely focused within the soundstage. This was easily verified in listening to the muppet’s version of "On Broadway" from kermit unpigged (Jim Henson Records/BMG 78400 10004-2). On this track I could discern (more clearly than ever before) the background antics and unique vocal stylings of Rizzo and the rest of "The Rhythm Rats," as they endeavored to master the various instruments used for this selection. I learned that it takes three rats to play the drums and further, that one rat hits the chords at the top of the guitar while another strums from the bottom--exciting stuff!!! By the way, this is a marvelous recording with mostly acoustic instruments and cameos by the likes of George Benson, Vince Gill, Don Henley, Linda Ronstadt and more--plus your kids will love it!

My feeling was that the greater clarity and focus I was hearing was the result of less interstitial noise rather than "air" being added to the sonic portrait. I use the term "interstitial," in reference to the noise component intertwined with the music signal. This noise, that rides on the signal, is passed on and amplified by all the various active gain stages throughout your audio system. The Power Plants are designed to remove this grunge at its source, the AC power line. Perhaps because of the marked decrease in this interstitial noise, mi’ amigo Senor Too-Sharp was able to hear more of the natural "air" surrounding the instruments. Because this noise was no longer competing with the music signal for my attention, all the instruments appeared to stand out more from their respective locations. This appeared to enhance left to right stereo effects and when the various sections of a symphony orchestra made their respective entrances in a classical piece, their arrival was all the more dramatic.

The bass was another area that appeared to benefit. On Madonna’s "Shanti/Ashtangi" from Ray Of Light (Maverick/Warner Bros. 9 46847-2) the complex bass lines were more distinct, more extended, and clearly easier to follow. But what really knocked me out was the almost surgical precision that the high frequency percussive instruments displayed. Each instrument sprang to life more vividly than I’d previously witnessed. In visual terms, it was almost as if I had paid a visit to my optician and let him snap progressively stronger lenses into position, until I could read that elusive bottom line with confidence and ease.

Gershwin would have liked the PS P300 too, because it rendered the sprightly piano work on his Rhapsody In Blue from Dayful Of Song (Delos DE 3216) sharper with less rounding. Yet there was no hardness or stridency. The initial transients were less blurred which made for a more engaging and expressive presentation of this wonderful composition. The piano has so many complex harmonics and the decay of the notes can overlap, and smear the subsequent progression of the polonaise. When a system starts to get that right then it’s really doing something special.


"Put it at the top of your short, must-audition list and YOU be the judge!"

Concerning the area of dynamic contrasts, I am somewhat at odds with my partner’s views. I will concede that given the diminished noise and the corresponding improvement in the palpability of the instruments, that one could argue for an enhanced perception of micro-dynamics. My system was already very dynamic to begin with and I don’t feel that I gained anything significant in that particular department. This was especially true of its macro-dynamic envelope. On the other hand, NTK thought there was a considerable improvement in his system’s dynamics.

Another point of contention is that Too-Keen felt that the overall presentation of his system with the Power Plant installed was more musical sounding. Contrarily, I thought my system had become slightly brighter and a bit more analytical with the P300 aboard. This is an apparent contradiction but it can be attributed to our respective differences in associated equipment and in our personal listening biases. Paul McGowan’s suggestion was to reposition my speakers, moving them a few inches closer together to flesh out the mid-bass of my system. I’m pleased to report that this did work to restore a warmer balance, while retaining the positive attributes of the Power Plant. Experiment!

That the imaging had improved was undeniable, because every sound within the soundstage was clearer. The noise component of the music, high frequency trash in particular was conspicuous in its absence allowing the instruments to emerge with greater distinction and presence. Lyrics and low-level details that had been previously smeared or obfuscated were rendered more recognizable and comprehensible using the Power Plant.

Regardless of the differences in our perceptions we can both agree, without hesitation, that the P300 is a remarkable product and that it does provide worthwhile performance gains. The benefits should be apparent in virtually every AC-powered audio system, no matter what its level of sophistication may be.

At its price of only $995 the P300 must be viewed as a bargain. It can be used to improve the performance of most source components--right where the improvements will be the most obvious. NTK has rated the Power Plant at FOUR GOOSEBUMPS so I will counter with THREE AND ¾ GOOSEBUMPS because although the results in my system were impressive, I deducted an extra ¼ GB for the trace of brightness I observed. BUT, the results in your system may vary. Put it at the top of your short, must-audition list and YOU be the judge!

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