This is a review, listening tests and detailed measurements of the PS Audio Stellar Power Plant 3 AC regenerator. It is on kind loan from a member and costs US $2,499.
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There are no front panel controls other than standby/power switch on the left. To activate the MultiWave and ClearWave requires remote control which I did not have. Very bad form to not put a simple switch in the front to cycle that way. Not much to the back panel:
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Shame there is no power sequencing/sense for power management.
A heavy AC cord is supplied with the unit but I got a kick out of this statement in the manual:
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You buy an AC regenerator and it still is sensitive to what the power cord does *before* it? And significantly so? For nearly $2,500 they could not provide said improved power cord either?
Despite being rather thin, this is a hefty box clocking at nearly 40 pounds (18 Kg). Yet, max power output is only 300 watts. There is a very high price to be paid here for regeneration of high voltage AC.
PS Audio PowerPlant 3 Measurements
We start by measuring AC power as it comes out of my outlet, followed by what the PowerPlant 3 does to it:
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We see that in addition to the 60 Hz mains, we have a lot of harmonics that come for the ride. You can see that the tops of the AC waveform are ever so slightly deformed as well. Measurement is performed using a 100:1 attenuator so actual output is 122 volts with distortion+noise of 1.9%. Here is the output of the PowerPlant 3:
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We see a good bit of improvement in harmonic content of the AC waveform on top right. However, that is accompanied with higher noise level as we saw in PS Audio's PowerPlant 15
. We can see that better if we zoom in the spectrum:
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This goes counter to company claim of noise elimination:
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But distortion is definitely improved. But let's see whether that matters to our audio gear which rectifies and filters AC anyway before use. To test that, I measured the output of my 15 volt linear power supply which comes from the company GRAS:
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There is essentially no difference between two sources of power. Reason is simple: the artifacts as you see them is created by the power supply, not from AC mains. So it doesn't matter how "dirty" the AC mains is.
What about output of our audio gear? I thought I use a low cost device that one would think needs more "help" from an AC regenerator. The volunteer was the Schiit Heretic headphone amplifier/preamplifier
. Here is its dashboard when powered by Raw AC:
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Despite being fed "dirty" mains, its produces spectacularly low noise and distortion that is 5 dB better than our best case threshold of hearing. There is some power supply noise but they are incredibly low level of -140 dB (25 dB lower than threshold of hearing). Now let's power it through PS Audio PowerPlant 3:
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What happened here? We took a hit in noise floor causing SINAD to drop by 2 dB. Who says we can't measure the impact of these products? We certainly can. In this case, I suspect a ground loop was created causing the increased 60 Hz mains spike. But I can't explain why the 180 Hz third harmonic has also gotten worse. Either way, we have gone backward.
PS Audio Stellar PowerPlant 3 Listening Tests
I created a chain from my RME ADI-2 Pro interface, driving Topping A90
headphone amplifier which in turn powered my Don Clark Expanse headphone
. I then played some of my reference audio clips. The sound was wonderful in its detail, and dynamics with inaudible noise floor. I then switched to powering the A90 with PowerPlant 3. It took 3 to 4 seconds for the A90 to play again which is not ideal in AB tests. I thought I heard some difference but when I switched back to raw AC, I "heard" similar difference. I am confident in instant AB switching it would sound identical.
As with tests of other PS Audio PowerPlants (of which, I own one myself but never use), objective tests do not show any improvement in performance of audio products. Yes, the distortion is reduced but noise is increased contrary to company claims. Because first thing our audio gear does is convert AC to DC, those components are filtered anyway. Certainly you can't get a high performance audio device that is so poor as to allow input AC noise to get through it. That would be the definition of non-fidelity!
Sighted, non-blind, slow switching listening tests are bound to produce impression of audio changing but as I experienced, this is due to any change, not because the PowerPlant. Human hearing is bi-directional and dynamic so can't be relied upon outside of controlled testing.
Let's note that the company doesn't show performance of any audio device being improved with this unit. Nor any controlled listening tests. Just a bunch of marketing claims that sound plausible but as you see form the measurements, don't amount to any improved fidelity. If anything, things have been made worse in some regards due to the architecture of the newer generation PS Audio PowerPlants which are not true AC regenerators (they mix AC mains with compensation signal). As I have shown in previous reviews, my lab grade regenerator performs a lot better.
In my opinion, it is a waste of technical talent to be building such products. I see no reason to recommend PS Audio Stellar PowerPlant 3.
Edit: Video review also posted:
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are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/