Product Review - PS Audio Power Plant P300 AC Synthesizer - October, 1999

Stacey Spears



Power Plant P300 AC Synthesizer

300 Watt Capacity

Outputs: 4 AC Outlets (115 Volts Balanced Power)

Size: 8.85" W x 5.5" H x 19" D

Weight: 30 pounds

MSRP: $995 USA

PS Audio International, PO Box 2037, Avon, Colorado, 81620, USA;
Phone: 877-772-8340; Fax: 970-845-0914; E-Mail  [email protected]; Web


Drinking commercial bottled water is commonplace these days, but 20 years ago if you were to tell me that I would be paying for bottled water, I probably would have laughed.  We already pay for water coming from the tap, so why on earth would I, or anyone for that matter, ever pay to get it out of a bottle?  Actually, I can remember growing up and drinking water from the kitchen faucet.  At home it was fine, but I disliked the water at everyone else's house because it tasted funny.  Then of course there is that old saying, “if you are going to Mexico, don't drink the water.”

Back when I was in the US Army, my unit deployed to Saudi Arabia for Desert Shield/Storm.  Here we were given nothing but bottled water to drink.  Let me tell you, not all bottled water is created equal.  There were certain brands of bottled water that I could not stomach, because they had such a bad taste.  Then there were those who would always clamor on about how water has no taste.  It was funny to see them eat their words as they sipped on some of the nasty stuff.

What has the water story to do with hi-fi?  While water is what our body needs to live, electrical power, on the other hand, is what our AV products need to live.  And just like water, power comes in many flavors.  So now you are probably going to laugh at me because not only do you need to pay for power from the wall sockets, but you are going to have to pay more for “good' power because what is coming out of your wall may not be the best for your gear.  Just recently the water in one part of the country was found not to be drinkable. If you were to drink it you would probably not function very well, and the same holds true for your AV products being fed by a contaminated AC supply.

Who is PS Audio?

Paul McGowan and Stan Warren founded PS Audio in 1974.  Their first product was a $59.95 phono preamplifier.  From there they grew, making power amplifiers, many more preamplifiers, integrated amplifiers, and eventually digital products.

Stan left in the early 1980s, and Paul left in 1990 to Join Genesis Technologies.  In 1998, PS Audio Inc. ceased operations due to financial problems.  Shortly after that, Paul bought back the name PS Audio.  In January of 1999, Paul left Genesis to rebuild PS Audio.  The first new product from PS Audio is the Power Plant P300, which is a Power Line Conditioner (PLC).

DC Galvanic Isolation

What?!?  That is the technical term for what a UPS (Uninterruptible Power Source) and the Power Plant do.  It simply means turning AC into DC then back into AC.  It is the ultimate approach for cleaning up those nasty noise makers that might be on the AC.

Are all AC-DC-AC converters created equal?  No way!  A lot of UPS devices intended for PCs do a poor job at this.  They essentially lay many square waves on top of each other, even though, according to Fourier's theory, if you lay enough sine waves on top of each other, you create a square wave rather than the other way around. Also, many computer UPSs inject high frequency distortion into the new AC, and this comes from the device used to generate the sine wave itself.

Does that mean that all UPS are bad?  Again, of course not. Some industrial UPS devices costing lots of $$$ do an excellent job.  A nice Toshiba UPS will run you about $3,495.  That is just one model that I investigated before I had even heard of the Power Plant.

The P300 actually employs a pretty interesting technique to regenerate a sine wave. It uses a Microchip PIC chip (DSP) with a lookup table.  They plot 1,000 points, their sine wave, in the lookup table.  This lookup table is then fed into a power amplifier to generate new AC.

Under the Hood

To look inside the P300, you must remove the bottom.  Yes, the bottom!  It seems the guts of the P300 are actually mounted upside down.  That explains why the top front runs hotter than a 100,000 BTU jet burner.

A. The first thing that happens is the incoming AC passes through an EMI filter.  Typically in most PLCs, you can't plug your power amp into the same socket that contains an EMI filter because they cannot run that much current through them.  The P300 is relatively small; I am not sure how the bigger units will be wired.

B.  From there, the EMI filtered outputs are fed directly into two center-tapped balanced input transformers.  They had originally used one, but under load it buzzed, so they spread the load across two transformers.  The transformer is used to step up the voltage to 143 volts (headroom for voltage regulation). 

C.  They use multiple Metal Oxide Varistors (MOVs) across the primary for surge and spike protection. These things react in billionths of a second to shut off the power..

D.  The AC then passes through a diode bridge for rectification, and is subsequently filtered by a bank of capacitors (the DC power supply).  They have to be BIG.

E.  The DC is then applied to the two power amplification stages, which are class A/B power amplifiers.

F.  A Microchip PIC chip feeds the power amplification stage (DSP-based sine wave oscillator). The input frequency is microprocessor-controlled and is user adjustable via the front panel.

If you look inside most PLCs, you will notice that from the transformer, only one set of hot, neutral, and ground wires are connected to a single AC receptacle.  From there, all of the other receptacles are daisy chained.  However, if EMI filters are used, then they are isolated from the rest of the outlets.

In the P300, each outlet has its own set of wires coming directly from the amplifier.  This is true brick wall protection between your components.

In Your Face

The front panel of the P300 is neatly laid out.  It has a nice aluminum finish with an LED display and 4 buttons. The power button, which illuminates the front panel, provides juice to the AC receptacles on the rear. The front panel illumination is represented by the letters PS as in PS Audio.  This is a blue translucent material.  A pilot light illuminates it from inside.

Next you have a mode button.  The default mode is the frequency the P300 is outputting. If you press the mode button, it switches to a wattage-use display.  The mode button then toggles between frequency and watts used.

The other two buttons are to adjust the output frequency, what PS Audio calls power factor.  The default output is 60 Hz and is adjustable from 50 Hz up to 120 Hz in 5 Hz increments.

A future upgrade will also allow 81 Hz.  This is supposed to be the optimal frequency for turntables.  Going on the same theory, I have asked for a 72 Hz option for video.  A progressive PC DVD player can output 72 FPS at 72 Hz for a smooth, judder-less picture.  Why not have your projector's AC running at 72 Hz as well?

While power factor is a cool term, and I am sure it will be a big buzzword for their products, I believe it can and will confuse people.  In the EE world, power factor pertains to the quality of the power being provided.  Poor power factor is caused by reactive loads from such things as fluorescents lights, motors,  and your PC's switching power supply.  This will cause voltage and current to depart from the ideal 900 phase relationship.  Power factor can be anywhere from 0.1 to 1, with 1 being a perfect power factor.  If the power factor is 0.3, you are in trouble. In the PS Audio world, it refers to the ability to change the frequency that the P300 outputs.

Note from Editor: Even though PS Audio's use of the term "Power Factor" may not be in the classical EE sense, it is their belief that power supplies of equipment plugged into the P300 will have an improved performance when the AC frequency delivered by the P300 is increased from 60 Hz to, say, 120 Hz. Thus, they call it a Power Factor. However, our analysis using calculus shows that the power and average voltage remain the same between the different frequencies. The diagram at the right shows the area under the sinewave curves for 0 Volts through 30 Volts and 30 Volts through 60 Volts, for both frequencies. Although the shape appears different, remember that the total power delivered within 1 second is represented by twice as many cycles with 120 Hz as with 60 Hz. One way there might be an improvement is with a higher likelihood that a peak voltage will be present during a transient demand with 120 Hz than with 60 Hz. However, further research is necessary to determine the value of increased power supply frequency.

My only real complaint about the front panel is the lack of a dimmer control or lights off switch.  If you have a P300 in your theater, it can be distracting.  The only light you want in the theater is coming off the screen.  All A/V products should allow you to dim or turn off the display.  I removed the pilot light to shut it off. I like my theater DARK!

Around Back

The back of the P300 is simple and well laid out.  There are two pairs of orange (with isolated ground, this can be identified by the green dot.) These have isolated ground. A green grounding post is also there for isolating the ground from the house.  Also present are a power inlet to connect the P300 to the wall, two RF F-Pin connectors for CATV (Cable TV), one input and one output terminal, and a master on/off switch.

I never actually used the CATV connectors.  They are tied to the chassis of the P300, I know how ugly the CATV signal is, and I did not want that contaminating any of my AC.

The only problem with the back of the P300 that I have found is the paucity of outlets.  Of course the P300 has very little room, but I still want more!  On the other hand, the P300 is designed for 300 watts, which can be used up pretty quickly. I picked up a three way AC plug, very heavy gauge I might add, and had great luck with it.  PS Audio offer's what they call a Link Adapter to add eight more outlets and some additional digital filtering. It retails for $249.

The Black & Decker Test

The very first test I performed, which I will call the power drill test, was to see if it could protect my products from inrush brought on by other household items or stormy weather.  Living here in the Pacific Northwest, we experience lots of voltage sags and swells during stormy weather. 

In my house, anytime someone uses a drill, saw, vacuum cleaner, or if  the heater kicks-in, the lights dim.  The P300 literature says that whether your incoming AC drops to 90 Volts or goes above 130 Volts, it will always output 115 Volts (this is called voltage regulation).

So, I plugged a fluorescent lamp into one wall outlet and a drill into another. Every time I squeezed the drill, the inrush caused the lamp to dim.  Then I plugged the lamp into the P300 and the P300 into the wall.  I repeated the test; and this time the light did not dim.  As far as Mr. Lamp was concerned, there was no drill in use.

After doing this, my fellow test aficionado Aaron and I carried the P300 into a hardware lab.  Here we plugged it into an Elgar AC generator.  We then plugged a FLUKE true RMS meter into one of the outlets of the P300.  The first thing we noticed was that it was not putting out exactly 115 Volts but instead 116.7 at 60 Hz.  We upped the frequency (Power Factor setting) from 60 to 120 Hz.  The meter then read 115.0 Volts.  More on this later, but it is by design.  We also plugged a Tektronix THS 730 Digital Oscilloscope into one of the P300 outlets.  We adjusted the output of the Elgar, lowering it until the output voltage and sine wave started to change.  We were able to get it down to 95 Volts before the P300 could no longer output 116 Volts.  We next raised the power to 130 Volts and again the P300 was fine.  The P300 was able to go from 95 Volts to 130 Volts input without affecting the output.  This was all under no load, so we next plugged in a fluorescent lamp and turned it up until the front panel display of the P300 read 280 Watts.  We repeated the above tests and we achieved the same results.

Ground Zero

To improve the performance of the P300, PS Audio recommends isolating the incoming AC ground from the outgoing by using the binding post on the back tied to an isolated ground (a pipe buried in your yard), after disconnecting the incoming ground from the outgoing ground on the inside of the chassis.

Upon opening the P300, I was following the instructions provided on how to disconnect the incoming and outgoing ground.  I discovered by following these instructions that you end up floating the ground.  On top of that, the grounding post is tied to the incoming AC, so you are still tied to the house ground.  An e-mail from PS Audio concurred with my findings, and it seems some of the P300s shipped had the wiring wrong for the ground.  PS Audio gave me two options, send the P300 back and they will fix it, or do it myself.  It was a pretty simple fix.

The way that PS Audio recommends tying off to a separate ground can be very dangerous.  If you have a ground potential between two products and you happen to touch both at the same time, it can be as harmless as a minor tingle or as dangerous as death!

Whenever you install a technical ground, it MUST be bonded to the house ground so that no ground potential exists.  While this is not the best place to explain how to install a technical ground, nor am I an expert, it is pretty simple.  Pound a new 8' copper rod into the ground about 6' from your existing house rod.  Bond those two rods together with a piece 6 gauge copper wire.  Continue running the house to the original rod and run your new, dedicated, outlets to the new rod. Providing that you used an isolated ground outlet, like a hospital outlet marked with a green dot, you can now just plug your P300 into the outlet and not even worry about using the ground post on the back or disconnecting the wires inside.

Under the Scope

I was anxious to see just how good the sine wave output of the P300 was, since this is the primary function of the unit.

First thing I needed to do was find a bad sine wave coming from the wall (pretty easy to do, and that is why the P300 was designed).  The one at home is not that bad off; but it is slightly clipped on the top and bottom.  I found a much worse sine wave coming from the wall at work, which is a sight to behold.  It kind of reminds me of a shark's fin.  You can see that in Figure 1.

FIGURE 1 - Wall FIGURE 2 - UPS FIGURE 3 - P300

Figure 2 is the output of a typical computer UPS when running on battery power.  Pretty ugly huh?  Figure 3 is the output of the P300 actually running off the UPS battery in Figure 2.  I would have included a Figure 4 here with the output from the lab at work, but it looks just like Figure 3.  The P300's transformers buzzed like mad when they were running off of the UPS battery, but the output was rock solid and super clean (suffer, you miserable transformers, suffer).

I have a few things to note about Figure 3. First you will notice more than just the sine wave.  Because the PS Audio outputs balanced power, we had to measure channel 1 and channel 2.  You can see the output voltage for each side on the right marked Ch1 and Ch2.  Channel 1 and 2 are the smaller sine waves.  The big sine wave is actually created using the math function on the scope.  I must note that what you are seeing is after a slight modification I made to the P300 (explained below).

All AC-powered hi-fi equipment has to rectify the AC into DC before it can be used.  These products are also designed to deal with varying voltage levels and harmonic distortion.  It's not the how pretty the sine wave looks that is the big deal, it is the harmonic distortion (THD) and impedance that really matters.  Some cheaper UPSs, like the one used for Figure 2, may be as high as 10% THD.  The P300 claims that it outputs a sine wave with 0.01% THD.  Since I do not have a harmonic analyzer at this time I cannot validate that claim.

Before I get to the modification, I must explain why I would even do such a thing.  One of the first things I did was plug in a Radio Shack circuit tester to see what it said.  It reported, “open ground.”  The P300 is balanced, so the output of a circuit tester will give you non-standard results.  So I next plugged the circuit tester into my reference Equi=Tech Balanced power transformer, and it reported, “hot and neutral reversed.”  OK, now I was confused.  I was able to track down a Cinepro balanced transformer and it too reported, “hot and neutral reversed.”  So the question was why does the P300 report “open ground?”  Using a FLUKE true RMS meter, I tested for continuity on the ground.  Sure enough, the input and output ground were connected, so it was not floating the ground.  I was stumped for a few days, and it was not until I stumbled upon another issue that I found the solution to this one.

While taking measurements, I noticed that the phase of the AC in the output would change depending on load.  On top of that, the output voltage in the two channels was not equal.  One side might be 70 Volts while the other was 50 Volts.  Under no load, there was a wide voltage difference, but under full load, they were pretty close to equal.  Under less than half load, 120 Watts, there was about a 10-15 Volt difference between the channels.  With the largest variance between channels being 30 Volts, that only offers about -6dB of noise attenuation.  When there is perfectly balanced AC, it is theoretically possible to achieve -30dB of noise attenuation.

And as I said above, the phase between the channels would change, which can be a bad thing.  I guess I had better first explain how I was taking these measurements.  I took an old 3-prong power cord and cut the equipment end off.  The black wire was tied to channel 1 and the white to channel 2.  The grounds of both probes were tied to the green (3rd prong ground) wire.

I sent these results off to PS Audio because I knew something was not correct.  This is when they explained to me that the circuit ground and the output ground were not tied together.  They use the center-tapped output of the transformer for circuit ground.  They also explained why they did this: they wanted to keep the house ground from dropping noise into the amplifier that is creating the new AC.  They also said that hi-fi equipment does not care about the 3rd prong, because it is just there for fault.

To confirm what they had told me, I tied a wire from the input circuit ground to the output ground.  Sure enough, the output measurements were now dead on, 58.9 Volts on one channel and 59.2 on the other.  That is about a 400 mV (± 100 mV due to meter accuracy) difference between channels, which is really good. The Equi=Tech has about 100 mV difference.  The phase was also right were it should be.  I plugged in the RS circuit tester and it now reported, “hot and neutral reversed.”

Now let me get back to the 3rd prong fault theory.  A lot of components only have 2 prongs (hot and neutral).  They take the hot and neutral wires and run it through a center-tapped input transformer, which will output not only a hot and neutral but a ground as well. I do have several AV products that have 3 prongs.  Some 3-prong components take the 3rd prong and tie it to the chassis for fault and then generate a new ground from a center-tapped input transformer.  Other actually tie the circuit ground to the chassis ground.  I have found that a few of my digital pieces depend on that 3rd prong for digital zero reference. 

Balanced Power 101

Unlike traditional unbalanced power that has a hot conductor (120 V) and a neutral conductor (0 V), along with ground, balanced power gives you +60 V on one conductor and –60 V on the other conductor, relative to the ground conductor, giving you 120 V total.  Why is this important?  Balanced power provides common mode noise rejection (CMR) to eliminate noise.

Let me digress for a second and explain, in more detail, the importance of proper balanced power.

There should only be one ground reference for all signals, and this is what is called your "signal reference."  In a balanced power system, the voltage of the power source defines the ground reference itself.  All grounding connections are made at the single point signal reference and then on to earth.   Ground is located halfway between the voltage peaks, and this is the " zero crossing point" of the AC sine wave.  It is very important that the balanced output be perfectly balanced, because if it is not, then you do not get the full benefit of balanced power (duh!)

With balanced power, all the audio grounds and other signal references quiet down with good ground continuity.  The AC ground now magically becomes the quietest ground around instead of the noisiest.  You lose a lot of CMR if you don't.  "Common mode" means a common reference point for two identical but inversely phased "other points."  Without a common reference point, how could there be a common mode with which to have "common mode rejection?"  Common mode implies that there is a common ground.

The difference here is that ground, now, once and for all, has been defined as the "mean voltage differential" of the seat of EMF.  Now, with proper and thorough grounding techniques, AC noise nulls out completely.  It must if all is balanced because the noise is now routed to its common null point instead of some other "ground" reference that wasn't based on the above.

Besides the technical explanation, does it really make a difference?  You bet!  But I will cover all that in the subjective section of the review.

My "mod" was a simple change to make. It just required adding two wires from the star grounding point to the grounding post.

What about Phase?

One last issue that may or may not have an effect is the phase difference when using multiple P300s.  First let's take a look at your house and how it is recommended you install dedicated outlets for your A/V system.

If you look in  your electrical panel, you will notice 240 Volts coming into the house. This is separated into two phases, both of which are 120 Volts.  The house is split between these two phases.  When installing dedicated outlets for your AV system, it is always best to wire all dedicated outlets on the same phase.

The P300 generates new AC via DC Galvanic Isolation (I like that term).  The phase of the new AC is based on the crystal oscillator feeding the amplifier.  If you hook up two P300s, it is possible for them to not have the same phase.

This would be a great place to add some type of communication link on the back of the P300 so that you can daisy chain many units and have their phase synched up.

The real question is does this make a difference?  I don't know because I only have one P300.  It is very possible that this will make absolutely no difference because all of your hi-fi stuff will rectify the incoming AC to DC anyway.  I just felt that I needed to bring it up.

So what!  Does it improve AV gear performance?

After reading over my review, you may think I am picking on the P300. I want to assure you that I am not.  I wanted to objectively verify all the claims made and so far it does everything that it promises!  The only thing I can't measure at the moment is harmonic distortion.

Portable DVD test

The following is a similar finding to that with the Equi=Tech, and it is a true testament to balanced power.  If you did not read my review of the Meridian 861 , I have switched from the Meridian 565 surround processor to the Meridian 861.  The 861 utilizes a FIFO RAM buffer to de-jitter the incoming signal.  I quickly learned that not all digital sources work well with this. If the source is EXTREMELY bad, you may end up with problems.  At least I did.

The problem I encountered was only when I used the Panasonic LD-10 Palm Theater portable DVD player.  I would get about 15 audio dropouts per movie.  I must have watched 20 movies, and each exhibited the exact same problem.  I did not have this problem with the Sony DVD player and the 861, nor did I have it with the 565 and the LD-10 when used together. It was just with the 861 and the LD-10.

After inserting the P300 (and the Equi=tech before) into the chain, the dropouts vanished!  I had not been expecting this when I tested the Equi=Tech, but I did expect it now with the P300.  It has been said that balanced power can lower digital jitter, but I thought it would not be noticeable with the Meridian FIFO.  Man was I wrong!  Just to verify I was not hallucinating, I watched another 15 or so films, some of the same movies I had experienced the dropouts with prior to the P300 and nothing, not a single audio dropout occurred!  I removed the P300, and the audio dropouts returned.

From what I can tell, the power supply in the Panasonic LD-10 is pretty bad, but after all, the LD-10 was designed for portability.  Unfortunately, using it as a portable means you won't be connecting it to the P300, but my experiences show that using balanced power does indeed improve the digital bit stream output from DVD players.

On the Big Screen

Towards the end of the review I connected the Dwin HDP-500, Dwin TranScanner (TS), and Sony S-7000 to the P300.  Initially the HDP-500 used 250 Watts on startup.  After a few moments, it backed down to 220 Watts.  I put on a 100 IRE white field, and it remained at 220 Watts with an occasional jump to 230 Watts.  I next plugged in the TS.  Power usage did not change much.  Same thing when the S-7000 was plugged in.  During the movie, the value would change from 220 up to 250 Watts.

A subsequent viewing session did not work as well.  While it never went above 260 Watts, the P300 did shut down.  I also experienced this when my little Toshiba TV was plugged in with the rest of my gear.  I believe it shutdown because of heat. If the P300 gets above a certain temperature, it will shutdown.  It's a safety feature.

I noticed one thing right away that there was more depth to the picture.  A couple of weeks ago I spent a few days with a Faroudja VP-251 line doubler.  The 251 gave improved depth compared to the TranScanner.  On Chapter 3, Jump Ball, of "Star Ship Troopers", at about the 9 Minute 54 second mark, when Johnny Rico (Casper Van Dien) performs a forward somersault over Zander Barcalow (Patrick Muldoon), I could perceive improved depth of field.  In front, you have both characters flying through the air, and behind them is an AT&T billboard with a crowd of people standing behind that.  And behind them is some sort of “Fight Future” flag hanging from the ceiling.  With this scene you can tell that Rico is closest to you with Zander flying back into the crowd of people.  There are several layers deep of people with the flag some distance behind them. 

This is not always obvious with the TS.  With the TS by itself, it is like they are all at the same depth on top of each other.  With the P300 in place, the TS is now able to convey the depth that the 251 has.  I wonder what would happen if I plugged the 251 into the P300?  Perhaps that can be answered in the future.

Evan Upchurch pointed out to me that there was the lack of switching noise from the HDP-500.  The 500 has this intermittent noise that can be heard with nothing else on in the room.  This noise is high pitched and lasts a few seconds, goes away, then repeats itself.  It seems to change with the image on screen.  When the HDP-500 was plugged into the P300, no such noise was evident.

A third thing that I noticed is improved black (the improved black was most noticeable once I tied the two grounds together as mentioned above).  When I had just the TS and S-7000 plugged into the P300 and the projector plugged back into the wall, the black level was still better than before.  The black bars on a DVD (letterbox), are not really that black.  This quickly becomes apparent when you see it next to something that is blacker.  Most high-end projectors let you adjust the blanking on all four sides of the screen. I use this to cover up the black bars in a letterbox movie because they are blacker.  While watching "The Corruptor" on DVD, which has an aspect ratio of 2.35:1, I noticed that the DVD's black bars were just as black as the projector's blanking.  I had the TS set for a 1:85:1 aspect ratio, and the memory really requires the same squeeze as 2:35:1. It is just that I have the blanking pulled down further to cover the thicker black bars.  Black bars can be distracting for many viewers, but when you have two shades of black, it compounds that dissatisfaction.  With the P300 in place, the two shades of black appeared as one.  The animated image on the left shows you before P300 black on top and P300 black on bottom for DVD bars.  This is just a simulation of what I experienced.  You will notice that the top bar appears to be black until the bottom reference is displayed.

I was watching Matrix, again, last night on the Toshiba TV.  There are many scenes that are dimly lit.  Both the letterbox bars and the scenes themselves were extremely black and noise free, with the P300 in the system.  In fact, there were some pitch black scenes where, if I did not know any better, I could swear the TV was not even on!  This time I just had the DVD player plugged into the P300. 

Did someone order extra resolution?

I was blown away by the improved audio resolution I was hearing from the Meridian 562V/518/565, Parasound HCA-1206, and Monitor Audio combination!  I have heard Holly Cole many times in the past, but not like this.  This setup is located in the “mini-theater” which is in a new room we are working on.  Room acoustics have not been dealt with yet, and believe me they need to be.  But I am still shaking my head at the resolution (my room mate thinks I am saying no to an additional helping of potatoes).

“I can see clearly now” is the piece of music that I played over and over again.  It is the opening cut on Holly Cole's, “Don't Smoke In Bed”  [CDP 0777 7 81198 2 1 Capital Records]. You can immediately notice the room acoustics that are buried deep within the recording.  It has always been there, but I never noticed how pronounced it was before.

I believe the effect that the P300 has on 96/24 music will be the biggest selling point.  The S/N ratio for 96/24 music is 144 dB, and I don't think there is anything out there today that has a noise floor that low.  Without the P300 and its balanced power, you are never going to hear all the nuances that are buried in the music.  The noisy background that can be attributed to poor AC and poor grounding will mask some of the finer detail. With the P300, you are able to get a lot of that back because the background is so incredibly quiet.

I also found that I had to do a slight re-adjustment of my speakers because the imaging changed with the P300 in place.  Less toe-in was required with the P300 than without.  This gave me a wider soundstage without losing the pinpoint imaging I like.  Not only was there improved depth with video, but audio had much more as well.  Back on Holly Cole, she was clearly out in front of the musicians.

One thing I noticed on the front display is that when you have the PF set above 60 Hz, each device uses more power.  I have read many positive things on the net about using various frequencies, but I did not really notice a difference.  I played at 60 Hz, 90 Hz, and 120 Hz for most of my listening.  Power supplies in existing products are designed to work at 60 Hz, but they also must be able to handle changes.  Some products transformers will actually hum when running at a higher frequency.  I did not encounter any humming with my components, even at 120 Hz.

I found that things worked best when I did not use over 200 Watts.  The P300 ran much cooler.  Under full load it puts out more heat than some high-end power amplifiers.

The P300 has educated me on how my other AV gear behaves.  For example, I never knew that my DSS pulls the same amount of power whether it is on or off (60 Watts all the time).  The Meridian 861, which has a max rating of 100VA was using anywhere from 90 to 110 Watts of power.

I must mention that the P300 is really an audio amplifier that is supplying all of this great, noise free, AC.  The P300 is not very efficient in this way, and it may actually use up to 500 Watts, just to power itself, while providing you with only 300 Watts.

What about Power Cables?

PS Audio has also come out with the Power Link which is a 2-meter power cord.  I am not going into all the arguments about fancy power cords out there and the things they promise.  However, there are some important requirements with power cords that most stock cords do not address.

Shielding is one of the most important things.  All power cords from your components generally go to one location, and they are usually tied together or laid on top of each other.  They also tend to cross paths with your AV interconnects and speaker cables.  The power cords need to be shielded from each other and the audio/video cables.  This is generally accomplished by using twisted cables or lots of foil.  The PL is heavily shielded.

Next, a power cable must use a thick enough conductor to allow adequate power to flow to your equipment.  The PL is thick!  It loses some flexibility because of this, but it is still manageable.

And finally, a power cord needs to make a good connection to both the wall and product.  The PL uses high quality connectors on both ends.

My only complaint about the PL is its fixed 2-meter length.  I would like to add one to my projector, but I will need much more than 2-meters.  The PL is not cheap, but it is much less than most of the esoteric power cords on the market.  It can be had for $149.50.


Many power line conditioners on the market today make big claims, and many of these claims are often based on some type of black magic voodoo or alien technology, but the Power Plant from PS Audio really works!  PS Audio is offering a 30 day money back guarantee, so you can try it in your house and see if it works with your electronics.

Most of my equipment is built to high-performance standards, and the improvements I saw and heard were dramatic.  I can only imagine what the effect will be on more mass market products.


  • Output voltage rock steady
  • 0.01% THD Sine Wave
  • Balanced Power


  • Front panel display is not dimmable
  • P300 only supports 300 Watts
  • Only four AC outlets
  • Circuit ground is not the same as output ground by default
  • Inefficient use of power (requires 500 Watts input to output 300 Watts)

I don't know if you can tell, but I really liked the P300, and I look forward to its bigger brothers.

Associated Equipment

Stacey Spears

© Copyright 1999 Secrets of Home Theater & High Fidelity
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