PS Audio PowerPlant 12 Review (AC Regenerator)

[Billy Budapest]

I do have to give PS Audio props on one thing—truly excellent customer service. I used to own a PS Audio Quintessence which was a passive power filter (basically, just a big power transformer) and surge suppression device built into one of their gorgeous Power Plant cases designed by BMW design. (They look way better than the current crop of PS Audio products, btw).

Anyway, BEFORE I purchased the Quintessence, I had mentioned on a public forum that I was going to purchase a Quintessence to help deal with a ground loop issue I was having. Paul McGowan himself jumped in and recommended that before I purchase a Quintessence, we should troubleshoot my ground loop issue. He helped me troubleshoot it and we could not find a solution. Afterwards, he said that the Quintessence might work to eliminate the ground loop, but that is not what it was designed to do.

I was set to buy the Quintessence but stumbled upon a fantastic deal on a PureAV PF60 power conditioner and purchased that instead. Lo and behold, it fixed the ground loop issue.

Fast forward a few years later. I needed another power conditioner and remembered how helpful Paul was and finally decided to purchase a Quintessence.

A few months after I purchased it, the Quintessence stopped working. The surge suppression components were built into a pull out module. When my unit failed to turn on, they quickly traced it to that pullout unit, paid shipping to and from their factory, and promptly repaired and returned it.

The Quintessence worked flawlessly for years, until it developed the same problem. By this time, the Quintessence was out of warranty and out of production. PS Audio told me that they no longer had any more pull-out modules in stock, but I could trade in my unit for a PS Audio Dectet for a set fee of $75, including shipping to and from. The Dectet was less fully featured than the Quintessence, but I thought it was a fair deal. The Dectet served me for a few years until I replaced it with a SurgeX unit. It’s now in my closet.

 

[Everett T]

Will it maintain voltage with fluctuation? My area 230V can swing up to 243V

I'd think you would want regulation at the mains in, not just for certain pieces of gear. Probably cheaper too

 

[anmpr1]

I found it to lower my noise floor (especially playing records), so much so that you can hear the difference without anything playing.

I wish I'd been clever enough to have thought that line up. Top tier comment! (You were making a joke about this thing, right?)

On the other hand, if I'm going over the cliff with this stuff, I'm not riding with Paul. It's the Fremer approved Whole House Rewire, or it's nothing. I mean, what's another ten large, when it comes to front to back depth, imaging, and plankton? Especially if it's for your mom!

In typical Fremer fashion, he did say that the P12 was a pretty good stand-in. And it was a bargain at $5500.00. But nothing like a $15,000.00 whole house rewire, which he assured us that any hard-core audiophile must have... if only for mom.

 

[kongwee]

I'd think you would want regulation at the mains in, not just for certain pieces of gear. Probably cheaper too

I can't, living in apartment. Have to regulate at substation. Of course, out of my control.

 

[Mart68]

Nah, In Canada Power companies won't do anything past the electrical entrance of the building, problems are with old buildings wiring, standards and distribution. Sure house owners can redo the whole thing, but it's far from cheap.

tell me about it. My wiring is fifty year old and needs re-doing, although it doesn't give me any sound quality issues.

If you can be specific about the audio-related issues there's certainly people here knowledgeable enough to advise on solutions.

 

[Everett T]

I can't, living in apartment. Have to regulate at substation. Of course, out of my control.

Contact the power company and ask what your options are since you rent, that's were I'd start. These are what are considered acceptable swings in the United States FWIW

 

[PeteL]

tell me about it. My wiring is fifty year old and needs re-doing, although it doesn't give me any sound quality issues.

If you can be specific about the audio-related issues there's certainly people here knowledgeable enough to advise on solutions.

Sure, just generalities, like there was a hum in my Monitor Audio silver series sub in my old appartment, fixed it by jumping the ground pin, not a solution I like. In my new place, no issue. What would have been the correct way to fix that in the old place?

 

[Ismapics]

This is a review and detailed measurements of the PS Audio PowerPlant 12 (P12) AC regenerator. It is on kind loan from a member and costs US $5,499.
View attachment 189600
PS Audio nails the industrial design of the unit. I really like the casework as well as the look of the various graphical meters as you see above. There is even network/Ethernet support to monitor them over time and remotely:
View attachment 189601
This is one heavy unit though despite its svelte height. Here is a shot from underneath:

View attachment 189602

Looks like we have a toroidal transformer on bottom right and power supply circuit to its left. Then on top is the AC regenerator which is basically a high voltage mono amplifier fed by a specific frequency (60 Hz in my instance). There are large heatsinks on the amplifier cooled by those two fans. I don't know if it sucks air from bottom or what. If it is, the feet are too shallow to allow good airflow. You better not put this on top of anything else that generates heat for the same reason.

After I took the above picture with the P12 on its side, I went to rotate it down and something really sharp poked and tore up my finger. Put it back up and noticed that there are two sharp points in the sheet metal (one indicated with the arrow). Not only is this dangerous from handling point of view but also is poor design as they can catch and bend in or out. The two sharp points should have been wider and connected to each other (vertically). The tip of my finger is hurting a bit still as I type this.

In case you are not familiar with this class of device, they take AC input, convert it to DC. That DC is then used to drive a power amplifier that is driven by mains frequency. Idea is that they can generate AC with lower distortion+noise than what the power company provides you. One wonders what cleans its own power supply if one needs a clean AC to drive audio equipment but we digress.

Company advertising makes lofty claims that are sadly not backed by any measurements:
View attachment 189603


"Sine-wave-perfect?" Nothing perfect exists in real life so that for sure is a stretch. How much we will see in measurements.

As usual there is also the claim of lower noise:
View attachment 189604

Again, if we can "expect lower background noise," why not show it to us in a measurement?

Being a high powered unit (think 800 watt amplifier), I worry about longevity and was reasonably happy to see a 3 year warranty. But then it had these exclusions:
View attachment 189605

Preventative maintenance? What would that be? Can't imagine they are asking the customer to open a unit lethal high voltages in it to clean those fans or circuits. The bigger issue is "connection to an improper voltage supply." Come again? I thought the purpose of this unit is to take improper AC supply and clean it up. And how would the customer know what is improper anyway?

Anyway, being an expensive product of its kind, the following testing is also a lot more expensive. To understand the flow, this is what we have here:

Raw AC Mains. This is what is powering my desktop computer, Audio Precision APx555 analyzer and any audio device I usually test. I measure this so we know what we are working with.

PS Audio P12 Output. The P12 takes raw AC and converts it to DC. It them modulates it with a sine wave with output regulated/nominal 120 volt. I measure this output and compare its quality to raw AC and my lab AC regenerator (BK Precision 9801).

Audio Power Supply Output. Almost every audio device also converts the incoming AC to DC. So I took both a switching and linear power supply and measure the DC spectrum of noise and distortion powered by either raw AC or PS Audio. If the theory of these products is correct, then the DC output of the power supply should be cleaner.

Analog Output of Headphone Amplifier. I tested a Topping A90 high performance headphone amplifier with both raw AC and PS Audio P12. Unlike the above tests, this is an actual test of fidelity and ultimately all that matters. The rest of the measurements help us understand what we are seeing here but ultimately they don't matter. Testing is performed both at one frequency and full suite of frequencies.

Let's get started.

AC Measurements
This is tricky business as we are talking 120 RMS volts (peak about 170 volts). This would damage the input stage of many measurement devices. Fortunately I have a differential AC probe (helps with not picking up stray signals/noise) that also has a 100:1 divider. This brings the voltage way down allowing me to use my Audio Precision analyzer with its full resolution to analyze AC power. This gives us far, far more accurate results than any AC line analyzer. First, we need to make sure the differential probe is not limiting the measurements so let's test it:

View attachment 189607

26 volt is output by Audio Precision APx555 and then looped through the differential probe. As you see, the voltage is divided down to 0.26 volt (100:1). The probe is creating just a second harmonic that is at -95 dB. Add some noise to it and our SINAD drops to 81 dB. For audio equipment that is not great but for measuring AC it is extremely good as what we are testing has far more noise and distortion as you shortly see.

So now let's measure the Raw AC in my lab:

View attachment 189608

Our AC waveform is distorted (tops of sine wave are rounded a bit) and noise added. If you look on top right, you can see what we have. The first tall spike is at 60 Hz which is the wanted frequency. But we also get a spray of harmonics at its multiples. We could treat this as a normal audio signal and compute its THD+N as show which is about 2%. P15 provides its own measurement but it underestimates it by a bit:
View attachment 189610

Maybe it is ignoring noise and just showing THD.

Now let's fee the Raw AC to PowerPlant P12 and measure what comes out of it:

View attachment 189611

We see a sharp reduction in harmonic spray with P12 resulting in our SINAD climbing from 36 dB (raw AC) to 67 dB (output of P12). We get a true THD+N of 0.46 which is much higher than 0.1 shown by P12 (0.1%). Fortunately we are still within the spec for P12 as I have copied and pasted in the center of the graph (< 0.5%).

I did notice raised noise floor though relative to our AC mains which surprised me. So I drilled down:

View attachment 189612

RAW AC is in blue, and once passed through PS Audio P12, in red. We see that the red has lower harmonics but has much higher noise floor across the full spectrum of audio.

Let's compare the same to my BK Precision 9801 lab AC generator (about US $2,600):

View attachment 189613

Notice how SINAD has shot way up to 65 dB now, courtesy of much lower harmonic distortion and noise. We can compare them again using the spectrum analyzer:

View attachment 189614

So as an AC generator, the P12 is quite a poor one. Granted, my 98091 is rated at 300 volt-amp and the P12 is 1000 so maybe we allow some difference in distortion but not this much.

The unit as shipped and tested by me comes in "high regulation" mode. It keeps the voltage constant at the expense of distortion. So I thought I change the mode and compare:

View attachment 189615

I am not seeing a difference. Maybe under heavy load it acts differently.

While on topic of not making a difference, there is a multiwave setting that goes from 1 to N. I changed that from 1 to 6 but it made no difference whatsoever in the output. I thought multiwave was for unit to generate different waveform than single 60 Hz. I like the company to show and document the waveform difference as you change this setting.

There is always an argument around these devices that they clean up noise above audible band. So let's test for that with 1000 kHz or 50X our audible band and see what is going on:

View attachment 189618

We see that the results are the same and not much is going on above 100 kHz anyway. The lab generator remains cleanest with P12 having higher noise floor at lower frequencies but lower distortions than AC mains.

Audio Power Supply Noise and Distortion Measurements
Let's start with the output of a small switching power supply that powers a Topping DX3 Pro which I had handy. Here is its spectrum when fed by my normal AC mains:

View attachment 189616

I have heavily zoomed the vertical scale so that we can see what is going on. At normal scale it would look like a flat line that DC would. We see the worst case of noise is a spike between 1 and 2 kHz. Its amplitude is at -65 dB which may be objectionable. But remember, this is the raw DC going into the Topping DX3 Pro. Secondary voltage regulators and filtering is used to clean this up before use. But let's go with it and compare it to when we power the power supply through P12:

View attachment 189617

I say no difference but the output of P12 seems a bit worse with our spike now rising a few dBs. That nit aside, none of the "nasties" have been removed. Reason is simple: bulk of them are generated in the power supply. The incoming raw AC was converted to DC inside this power supply and filtered. So what the P12 cleaned up was not material.

Another class of audio power supply is linear. For that, I grabbed the external DC power supply that came from my GRAS headphone measurement system. Here is its output when fed from raw AC (blue), PS Audio P12 (red) and BK Precision 9801 lab AC (blue):

View attachment 189624

The process of getting DC from AC involves first flipping the negative cycle of the AC sine wave to positive. This doubles the frequency of the mains input and shows up as a result as 120 Hz spike. We see that there is no difference between the three methods of input AC. As with the switching power supply, the noise is created inside the power supply so nothing you do before it makes a difference.

Actually one bad thing happens as noted: we now have a bit of a ground loop/leakage with both AC regens at 60 Hz. Anytime you string another AC source with its own power supply, grounding, etc. you increase your risk of creating ground loops and that is what we see here. So don't think these regens help with ground loops. They can very well create them. And if they fix them, it is an accident and not by design.

The conclusion here is simple: neither power supply cares about how clean the incoming AC is. So whether you clean it some with P12 or a lot with my 9801 generator, it makes no difference. There is noise in the output of the power supply which the audio equipment filters before usage. It is that filtering that is important, not what is done on AC waveform.

Topping A90 Measurements
I imaging anyone spending nearly $6,000 on an AC generator, is also investing in state of the art equipment when it comes to noise and distortion. I decided to test my Topping A90 since a reviewer quoted by PS Audio tested a headphone amp with P12:
View attachment 189635


Here is how it performs using raw AC input:

View attachment 189629

Same stellar performance we have seen before. Notice how the FFT shows no mains harmonic distortion, proving that it has effectively filtered them all. So it clearly needs to help from cleaner AC but let's give it that and see what happens:
View attachment 189630

Notice how mains leakage has increased a bit as I showed in pervious measurements. Fortunately it is still so infinitely low level to not be of concern.

I then ran a broadband frequency sweep, capturing noise+distortion:
View attachment 189632

Again, vertical display is zoomed. Strangely, the PS Audio P12 (red) has made things worse here! We are losing about 1 to 1.5 dB of performance. To figure out why, I analyzed the full 90 kHz spectrum of the output of A90 while playing a 1 kHz tone:

View attachment 189633

There is a spike at 68 kHz which is likely the switching frequency of some component inside the A90. Its level with raw AC is -122 dB which is extremely low so normally not a concern. But for some odd reason, when powering the A90 with PS Audio P12, it raises by 1.8 dB which is the difference we are seeing in measurements!

Not that it matters in grand scheme of things but it is interesting how our intuition is wrong in assuming that an AC regenerator always makes things better. It didn't in this case.

Why Owners Report Better Fidelity
There are countless people who buy these products and swear by them. How is that possible seeing that measurements don't remotely back them? Simple: improper testing. P12 is inserted in the system, listener pays more attention and now has a different impression of music. He hears more detail, more air, etc. He then decided that the theory of the power regen is proven. When taking it out of the system, expectation is that it will sound worse and it will. This is all part of being human.

A proper test would involve doing the above test blind. With analog devices like headphone amp, you should be able to move the power cable quickly between AC mains and P12 without the playback system needing initialization. Have someone do this type of quick switching (or slow if you like) and see if you can get > 8 answers right out of 10. If you do, then we have statistically significant results. Otherwise there is no there, there.

Conclusions
I hope you appreciate the comprehensive assessment that I presented to you above trying to tease out in every possible way what the P12 does. At high level, yes it is an AC regenerator capable of producing less distorted AC waveform. Strangely though, it adds noise of its own in low frequencies and doesn't perform anywhere close to my Lab AC Regenerator. My memory is that the older PS Audio AC regenerators were much better in this regard. So as an AC regen, the P12 is not that great of a device compared to what it could be.

The rest of the tests show why none of these power devices are capable of improving the output of our audio devices. They do nothing about noise generated by the power supply which is easily filtered in the audio device. You can't make your food taste better by washing the dishes you serve your food in multiple times!

Of note, deploying an AC regen causes power to be wasted, noise generated in the form of its fans, and reliability issues given the high powers and currents involved. You will incur good money shipping this unit back to the company to repair given how much it weighs (48 pounds/17 kilograms).

Before someone says, "but you haven't measured this and that," wonder why the company hasn't and published that! Send them your questions, not me. For a device that we can predict can't do anything useful based on simple engineering principles, we have done a ton to put proof behind our opinion.

Anyway, I can't recommend the PS Audio PowerPlant P12. I can't detect it making any improvement to your audio devices and costs a fortune to boot. Save your money and put it toward a better cause.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

This is a review and detailed measurements of the PS Audio PowerPlant 12 (P12) AC regenerator. It is on kind loan from a member and costs US $5,499.
View attachment 189600
PS Audio nails the industrial design of the unit. I really like the casework as well as the look of the various graphical meters as you see above. There is even network/Ethernet support to monitor them over time and remotely:
View attachment 189601
This is one heavy unit though despite its svelte height. Here is a shot from underneath:

View attachment 189602

Looks like we have a toroidal transformer on bottom right and power supply circuit to its left. Then on top is the AC regenerator which is basically a high voltage mono amplifier fed by a specific frequency (60 Hz in my instance). There are large heatsinks on the amplifier cooled by those two fans. I don't know if it sucks air from bottom or what. If it is, the feet are too shallow to allow good airflow. You better not put this on top of anything else that generates heat for the same reason.

After I took the above picture with the P12 on its side, I went to rotate it down and something really sharp poked and tore up my finger. Put it back up and noticed that there are two sharp points in the sheet metal (one indicated with the arrow). Not only is this dangerous from handling point of view but also is poor design as they can catch and bend in or out. The two sharp points should have been wider and connected to each other (vertically). The tip of my finger is hurting a bit still as I type this.

In case you are not familiar with this class of device, they take AC input, convert it to DC. That DC is then used to drive a power amplifier that is driven by mains frequency. Idea is that they can generate AC with lower distortion+noise than what the power company provides you. One wonders what cleans its own power supply if one needs a clean AC to drive audio equipment but we digress.

Company advertising makes lofty claims that are sadly not backed by any measurements:
View attachment 189603


"Sine-wave-perfect?" Nothing perfect exists in real life so that for sure is a stretch. How much we will see in measurements.

As usual there is also the claim of lower noise:
View attachment 189604

Again, if we can "expect lower background noise," why not show it to us in a measurement?

Being a high powered unit (think 800 watt amplifier), I worry about longevity and was reasonably happy to see a 3 year warranty. But then it had these exclusions:
View attachment 189605

Preventative maintenance? What would that be? Can't imagine they are asking the customer to open a unit lethal high voltages in it to clean those fans or circuits. The bigger issue is "connection to an improper voltage supply." Come again? I thought the purpose of this unit is to take improper AC supply and clean it up. And how would the customer know what is improper anyway?

Anyway, being an expensive product of its kind, the following testing is also a lot more expensive. To understand the flow, this is what we have here:

Raw AC Mains. This is what is powering my desktop computer, Audio Precision APx555 analyzer and any audio device I usually test. I measure this so we know what we are working with.

PS Audio P12 Output. The P12 takes raw AC and converts it to DC. It them modulates it with a sine wave with output regulated/nominal 120 volt. I measure this output and compare its quality to raw AC and my lab AC regenerator (BK Precision 9801).

Audio Power Supply Output. Almost every audio device also converts the incoming AC to DC. So I took both a switching and linear power supply and measure the DC spectrum of noise and distortion powered by either raw AC or PS Audio. If the theory of these products is correct, then the DC output of the power supply should be cleaner.

Analog Output of Headphone Amplifier. I tested a Topping A90 high performance headphone amplifier with both raw AC and PS Audio P12. Unlike the above tests, this is an actual test of fidelity and ultimately all that matters. The rest of the measurements help us understand what we are seeing here but ultimately they don't matter. Testing is performed both at one frequency and full suite of frequencies.

Let's get started.

AC Measurements
This is tricky business as we are talking 120 RMS volts (peak about 170 volts). This would damage the input stage of many measurement devices. Fortunately I have a differential AC probe (helps with not picking up stray signals/noise) that also has a 100:1 divider. This brings the voltage way down allowing me to use my Audio Precision analyzer with its full resolution to analyze AC power. This gives us far, far more accurate results than any AC line analyzer. First, we need to make sure the differential probe is not limiting the measurements so let's test it:

View attachment 189607

26 volt is output by Audio Precision APx555 and then looped through the differential probe. As you see, the voltage is divided down to 0.26 volt (100:1). The probe is creating just a second harmonic that is at -95 dB. Add some noise to it and our SINAD drops to 81 dB. For audio equipment that is not great but for measuring AC it is extremely good as what we are testing has far more noise and distortion as you shortly see.

So now let's measure the Raw AC in my lab:

View attachment 189608

Our AC waveform is distorted (tops of sine wave are rounded a bit) and noise added. If you look on top right, you can see what we have. The first tall spike is at 60 Hz which is the wanted frequency. But we also get a spray of harmonics at its multiples. We could treat this as a normal audio signal and compute its THD+N as show which is about 2%. P15 provides its own measurement but it underestimates it by a bit:
View attachment 189610

Maybe it is ignoring noise and just showing THD.

Now let's fee the Raw AC to PowerPlant P12 and measure what comes out of it:

View attachment 189611

We see a sharp reduction in harmonic spray with P12 resulting in our SINAD climbing from 36 dB (raw AC) to 67 dB (output of P12). We get a true THD+N of 0.46 which is much higher than 0.1 shown by P12 (0.1%). Fortunately we are still within the spec for P12 as I have copied and pasted in the center of the graph (< 0.5%).

I did notice raised noise floor though relative to our AC mains which surprised me. So I drilled down:

View attachment 189612

RAW AC is in blue, and once passed through PS Audio P12, in red. We see that the red has lower harmonics but has much higher noise floor across the full spectrum of audio.

Let's compare the same to my BK Precision 9801 lab AC generator (about US $2,600):

View attachment 189613

Notice how SINAD has shot way up to 65 dB now, courtesy of much lower harmonic distortion and noise. We can compare them again using the spectrum analyzer:

View attachment 189614

So as an AC generator, the P12 is quite a poor one. Granted, my 98091 is rated at 300 volt-amp and the P12 is 1000 so maybe we allow some difference in distortion but not this much.

The unit as shipped and tested by me comes in "high regulation" mode. It keeps the voltage constant at the expense of distortion. So I thought I change the mode and compare:

View attachment 189615

I am not seeing a difference. Maybe under heavy load it acts differently.

While on topic of not making a difference, there is a multiwave setting that goes from 1 to N. I changed that from 1 to 6 but it made no difference whatsoever in the output. I thought multiwave was for unit to generate different waveform than single 60 Hz. I like the company to show and document the waveform difference as you change this setting.

There is always an argument around these devices that they clean up noise above audible band. So let's test for that with 1000 kHz or 50X our audible band and see what is going on:

View attachment 189618

We see that the results are the same and not much is going on above 100 kHz anyway. The lab generator remains cleanest with P12 having higher noise floor at lower frequencies but lower distortions than AC mains.

Audio Power Supply Noise and Distortion Measurements
Let's start with the output of a small switching power supply that powers a Topping DX3 Pro which I had handy. Here is its spectrum when fed by my normal AC mains:

View attachment 189616

I have heavily zoomed the vertical scale so that we can see what is going on. At normal scale it would look like a flat line that DC would. We see the worst case of noise is a spike between 1 and 2 kHz. Its amplitude is at -65 dB which may be objectionable. But remember, this is the raw DC going into the Topping DX3 Pro. Secondary voltage regulators and filtering is used to clean this up before use. But let's go with it and compare it to when we power the power supply through P12:

View attachment 189617

I say no difference but the output of P12 seems a bit worse with our spike now rising a few dBs. That nit aside, none of the "nasties" have been removed. Reason is simple: bulk of them are generated in the power supply. The incoming raw AC was converted to DC inside this power supply and filtered. So what the P12 cleaned up was not material.

Another class of audio power supply is linear. For that, I grabbed the external DC power supply that came from my GRAS headphone measurement system. Here is its output when fed from raw AC (blue), PS Audio P12 (red) and BK Precision 9801 lab AC (blue):

View attachment 189624

The process of getting DC from AC involves first flipping the negative cycle of the AC sine wave to positive. This doubles the frequency of the mains input and shows up as a result as 120 Hz spike. We see that there is no difference between the three methods of input AC. As with the switching power supply, the noise is created inside the power supply so nothing you do before it makes a difference.

Actually one bad thing happens as noted: we now have a bit of a ground loop/leakage with both AC regens at 60 Hz. Anytime you string another AC source with its own power supply, grounding, etc. you increase your risk of creating ground loops and that is what we see here. So don't think these regens help with ground loops. They can very well create them. And if they fix them, it is an accident and not by design.

The conclusion here is simple: neither power supply cares about how clean the incoming AC is. So whether you clean it some with P12 or a lot with my 9801 generator, it makes no difference. There is noise in the output of the power supply which the audio equipment filters before usage. It is that filtering that is important, not what is done on AC waveform.

Topping A90 Measurements
I imaging anyone spending nearly $6,000 on an AC generator, is also investing in state of the art equipment when it comes to noise and distortion. I decided to test my Topping A90 since a reviewer quoted by PS Audio tested a headphone amp with P12:
View attachment 189635


Here is how it performs using raw AC input:

View attachment 189629

Same stellar performance we have seen before. Notice how the FFT shows no mains harmonic distortion, proving that it has effectively filtered them all. So it clearly needs to help from cleaner AC but let's give it that and see what happens:
View attachment 189630

Notice how mains leakage has increased a bit as I showed in pervious measurements. Fortunately it is still so infinitely low level to not be of concern.

I then ran a broadband frequency sweep, capturing noise+distortion:
View attachment 189632

Again, vertical display is zoomed. Strangely, the PS Audio P12 (red) has made things worse here! We are losing about 1 to 1.5 dB of performance. To figure out why, I analyzed the full 90 kHz spectrum of the output of A90 while playing a 1 kHz tone:

View attachment 189633

There is a spike at 68 kHz which is likely the switching frequency of some component inside the A90. Its level with raw AC is -122 dB which is extremely low so normally not a concern. But for some odd reason, when powering the A90 with PS Audio P12, it raises by 1.8 dB which is the difference we are seeing in measurements!

Not that it matters in grand scheme of things but it is interesting how our intuition is wrong in assuming that an AC regenerator always makes things better. It didn't in this case.

Why Owners Report Better Fidelity
There are countless people who buy these products and swear by them. How is that possible seeing that measurements don't remotely back them? Simple: improper testing. P12 is inserted in the system, listener pays more attention and now has a different impression of music. He hears more detail, more air, etc. He then decided that the theory of the power regen is proven. When taking it out of the system, expectation is that it will sound worse and it will. This is all part of being human.

A proper test would involve doing the above test blind. With analog devices like headphone amp, you should be able to move the power cable quickly between AC mains and P12 without the playback system needing initialization. Have someone do this type of quick switching (or slow if you like) and see if you can get > 8 answers right out of 10. If you do, then we have statistically significant results. Otherwise there is no there, there.

Conclusions
I hope you appreciate the comprehensive assessment that I presented to you above trying to tease out in every possible way what the P12 does. At high level, yes it is an AC regenerator capable of producing less distorted AC waveform. Strangely though, it adds noise of its own in low frequencies and doesn't perform anywhere close to my Lab AC Regenerator. My memory is that the older PS Audio AC regenerators were much better in this regard. So as an AC regen, the P12 is not that great of a device compared to what it could be.

The rest of the tests show why none of these power devices are capable of improving the output of our audio devices. They do nothing about noise generated by the power supply which is easily filtered in the audio device. You can't make your food taste better by washing the dishes you serve your food in multiple times!

Of note, deploying an AC regen causes power to be wasted, noise generated in the form of its fans, and reliability issues given the high powers and currents involved. You will incur good money shipping this unit back to the company to repair given how much it weighs (48 pounds/17 kilograms).

Before someone says, "but you haven't measured this and that," wonder why the company hasn't and published that! Send them your questions, not me. For a device that we can predict can't do anything useful based on simple engineering principles, we have done a ton to put proof behind our opinion.

Anyway, I can't recommend the PS Audio PowerPlant P12. I can't detect it making any improvement to your audio devices and costs a fortune to boot. Save your money and put it toward a better cause.

-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Great Review, again another product solving a problem that does not exist.

Has anyone ever reviewed this product: The "iFi DC Blocker" it makes incredible claims for $129.00, I would buy and send it to @amirm but its OOS. Same thing, solving problem that is just not there.

 

[sakiSagian]

good lord i paid about 3000 usd for my second hand hi end system and that thing is 2500 more.
Thanks i ll pass..

 

[NTK]

Thanks yes UPS certainly have use in some cases. I didn't say I need a power conditionner but I've come across many electrically induced, buzz-hums, interferences, it's certainly an issue for some, and when it is the case, what is the solution for it and what to look for. So input voltage spec is the one and only that matter in your view correct? Battery operation is a must?

I think the important point is the solution comes after knowing the problem -- one should avoid fixating on a solution before having a good understanding what the problem(s) is (are). Amir has shown several percents of AC mains THD does not matter to the DAC and headphone amps he tested.

UPS's are useful for brownouts and short duration power outages, and are useful to smooth out the AC mains voltage sags and surges during such events. Their batteries will supply the power when the incoming AC is not sufficient, so they can handle power dips much better than conditioners. The online UPS's run their inverters continuously and regenerate their output AC, so the output waveform quality is controlled. However, they may make audible noise during operation and may need to be placed in a closet or cabinet.

Depending on the reliability and quality of the utility power in your area, may be you need nothing (or for the peace of mind, a good surge protector). If I have money burning a hole in my pocket and an AC regenerator is what I must have, I'd spend just a little more and get this one:

AC6802B Basic AC Power Source, 1000 VA, 310 V, 5 A

This basic AC power source offers stable, reliable power up to 1000 VA. An intuitive user interface and flexible I/O connectivity.

www.keysight.com

 

[pinpoint_oxford]

I wish I'd been clever enough to have thought that line up. Top tier comment! (You were making a joke about this thing, right?)

I am not making it up. I did post earlier in this thread with the attached audio of what I get without the P12 in my chain from my record player (recorded from my phone with headphones and amp turned to max with nothing playing). It's quite an annoying sound and can be heard even at low volumes (especially between tracks).

Maybe noise floor was a poor choice of words, and it's also entirely possible the P12 "accidentally" fixed the issue, but a fix is a fix.

 

[Spkrdctr]

Interesting results, thanks for the hard work!

I'm interested in this bit especially. As someone who has suffered from ground loop issues in the past, I still don't understand how to fix them and prevent them despite hours of reading things (things I barely understand, mind you). I'd assume a device like this would help, but is interesting it appears to make it worse.

Edit: On a related note, I own a P12. In another thread about power regens I mentioned it helped with noise from my vinyl setup. Without the P12 in my chain I am plagued by this odd noise that I cannot identify. I recorded a small sample from my phone and headphones with my amp input on Phono and nothing else playing. If anyone can guess what this is maybe I could sell off my P12 and understand what is happening.

That is easy! That is the electronic noise that you find in an electronic cash register. It is counting up the amount of cash the power supplies make Mr. McGowan when he sells one. Paul is probably looking around the office for his P-12 cash counting machine and it is in your home! You were never intended to hear that and it should be sent back as Paul needs it!

 

[pinpoint_oxford]

That is easy! That is the electronic noise that you find in an electronic cash register. It is counting up the amount of cash the power supplies make Mr. McGowan when he sells one. Paul is probably looking around the office for his P-12 cash counting machine and it is in your home! You were never intended to hear that and it should be sent back as Paul needs it!

I wish it were that easy.

 

[Gremlins]

What a joke

 

[Spkrdctr]

I wish it were that easy.

Bottom line, your problem is fixed. That in itself is a big plus!

 

[sarumbear]

If manufacture does not produce test data for verification , bugger-off

That’s 99% of them

 

[pinpoint_oxford]

Bottom line, your problem is fixed. That in itself is a big plus!

That is true! I will also mention the MSRP of the P12 is well beyond what I nor anyone else should pay for this. I was able to find a great deal on this used for under $2k.

 

[Holmz]

There is no harm in trying a product like this.

OK - is there a benefit though?

Most companies (PS Audio included) have a free return period. I own a P12 and find it to be useful for my use case, old house with very dirty city power.

How dirty is it?
Which city?
How does one tell isf they are in a dirty city/

I found it to lower my noise floor (especially playing records), so much so that you can hear the difference without anything playing.

Is it like 10 decibels to 20? Or how would one quantify that?

 

[PeteL]

Is it like 10 decibels to 20? Or how would one quantify that?

The poster took the time to go to lenght of taking a recording of the nasty noise he was hearing and that was fixed by adding a P12.... This "show me that you have a proper measurment rig" or what you say is dismissed stream of argument is a bit counterproductive, who care how many DB it is if it can be clearly heard and picked up by a Iphone microphone... ?

PS Audio PowerPlant 12 Review (AC Regenerator)

You can't make your food taste better by washing the dishes you serve your food in multiple times! I get that washing my dishes multiple times won’t make my food taste better, but if I first plug my oven into a PS Audio Power Plant 12, will it make my food taste better?

www.audiosciencereview.com

 

[pinpoint_oxford]

OK - is there a benefit though?

Maybe, maybe not. My point is that if you think a device like this might help, a trial can help you decide.

How does one tell isf they are in a dirty city/

In my case, I have frequent voltage irregularities (measuring with a kill-a-watt periodically) from 108V-126V especially during the summer when many people are using their AC units.

Is it like 10 decibels to 20? Or how would one quantify that?

Good question. I haven't had a chance to do any measurements. I'll see if I can in the near future and follow-up. They won't be scientific, but now I'm curious as well.