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PS Audio P5 Power Plant

PS Audio P5 Power Plant

PS Audio is a Colorado-based company that was founded 40 years ago, and has made everything from DACs to preamps in that time. It still has a commanding reputation in digital audio and more recently high-grade phono equalisers. Regardless, PS Audio has become best known for its power products; when original co-founder Paul McGowan bought the name back in 1997, it was power conditioners, and specifically regenerators, that gained the brand the most interest. Where most power products that are made to improve the quality of the AC mains are essentially filters designed to remove as much noise from the mains signal as possible, regenerators effectively recreate the mains sinewave from scratch. 

Recently, PS Audio replaced its Premier regenerators with the Power Plant range. As well as being rather more attractive than its predecessor, this range has a number of distinct ‘firsts’. For starters, Power Plant models have a touch screen interface, which allows you to see the difference between incoming and outgoing AC sinewave. This lets the listener choose the best compromise between minimising distortion and degree of regulation, the latter for situations where the incoming AC mains fluctuates significantly. You can also choose to switch off outlets that are not in use, although there doesn’t seem to be a disadvantage in having them all powered up. Unsurprisingly for PS Audio (but less obvious on a power device), the Power Plant has a network connection and an SD card slot. The former means the Power Plant can report problems and show measurements online; it can even text or email you, which is perhaps a little more interaction than most of us need, but it’s certainly of the moment. The flash card slot allows firmware upgrades. The key difference between Power Plant and Premier is a 100x reduction in output impedance, which means a stiffer power supply, something from which all forms of supply could benefit.


The Digital Signal Processing that PS Audio uses to generate a new AC sinewave in the Power Plant models has a 16-bit, rather than 8-bit, DAC. They have also improved the software-based phase locked loop (PLL) circuit to make the Power Plant more tolerant of phase issues. The new regenerator can also cope with a wider range of incoming voltages: it can deliver a steady 220 to 230 VAC, while the power coming from the wall can vary between 190 and 275 VAC. However, I doubt that most of us in the UK see even a ten per cent swing. While the technology behind the regeneration process is digital the output stage is essentially a Class A/B analogue power amplifier that, in the case of the P5, has a 1250 VA output. 

The P5 is the middle model in the range and has four outputs for source and preamp type products, and a high current one for power amplifiers. I note that the US version of the P5 has eight outlets, on account of the smaller size of North American mains sockets. It always amuses me to see hawser size power cords struggling to stay connected to the tiny wall sockets at US shows. Also on the back panel are 12v trigger in/outputs, a reset button and a fuse. 

I’m a reviewer and a man. That means manuals are for other people. Sometimes this laissez faire approach to technology can bite back. The Power Plants are very particular about the way they are used. You can’t switch it on and plug components in; rather you have to plug everything in with the power switches off and then switch on the P5, allowing it to boot up prior to switching on the system. Bad things happen if you do it the other way, as I discovered when I (eventually) read the manual. 

I started off the assessment by hooking up the Akurate DSM streamer/preamplifier on the front of Linn’s Artikulat Aktiv loudspeakers. Having power amps in the speakers meant these could not be used with the P5’s single high-current outlet. The result was nonetheless quite obviously an improvement over standard mains. The sense of space and reverb on John Campbell’s Down in the Hole made for a larger image with excellent depth. The area where mains improving devices often fall down is timing, but this did not seem to suffer with the P5 inline. In fact, it was marginally improved. The extra openness clearly applies to elements other than image and the more I listened the clearer this became.


The P5 benefited some components more than others, power smoothing/regulation being ultimately something that all electronics designers try to manage. With Rega’s remarkable Saturn-R CD player/DAC used as a converter the improvement was nothing short of massive; the sound gained a radiance and vibrancy that brought out the full flavour of the music. Tone resolution went from being subdued to immediate; it put that very able machine into a whole other league. The Resolution Audio Cantata used as a streamer clearly benefited as well. The way the P5 cleaned up the flute on La Folia was remarkable; its purity was maxed because loads of what one perceives as grit, but which is essentially noise, was removed to let the music through. This really brought home the fact that electrical current is the lifeblood of reproduced music, and when that blood is polluted you can hear it. With electric instruments it’s not very obvious but acoustic ones, including of course voices, change quite dramatically when you clean up the ‘carrier’. 

It would be interesting to apply AC regeneration to not only the studio but the electric instruments being recorded, to see whether the music itself would benefit. But you might very well find that musicians like the sound of grunge.

Back in the listening room, I continued enjoying the deburring effect that the P5 was having on a range of music types; the way it removes the electric character from the chain is quite uncanny. Some will not take to it for that reason: if you live on a staple of heavy rock and electronica, the cleaning up may not be to taste. But ultimately, you are hearing more of what the musicians put down in the studio; a sound that in theory is closer to what they heard on the monitors at the time. I would be surprised however if anyone who appreciates good sound would dislike the result that the P5 gives with source components. It even benefited a Naim Unitiserve, which is essentially a well appointed rip/NAS: it put the sound more solidly in the room and produced a better vocal image. Nils Lofgren’s mistakes on ‘Keith Don’t Go’ are laid bare, as is the brilliance of his playing – it’s not perfection that makes a great musician as any Jimi Hendrix fan will tell you.


I had less success with power amps, the first one up was ATC’s substantial P1, a 150 watt class A/B taker of no prisoners. Putting this on the high current output made for a larger soundstage, but it lost dynamics. Some of the grip that this amplifier is so good at exerting had diminished. A similar experience occurred with a Leema Tucana integrated. It’s a similar amp in some ways, and one that had better leading edge definition and perceived transparency without the P5 between it and the wall. The regenerator made both sound cleaner, however, and this might appeal to some listeners. Quite possibly the higher output of the P10 Power Plant with its 1500 VA output would be better suited to high power amps.

I can highly vouch for the P5 with preamps, DACs, streamers, phono stages and pretty much anything that does not have to drive a loudspeaker. It brings a delicacy and finesse to everything it touches, Herbie Hancock’s piano on his version of ‘Court And Spark’ on The Joni Letters [Verve] had so much subtlety and feeling that it seemed in-room real. Streamers really benefit; it’s like going from 2D to 3D with some records, like bringing the venue of a live performance to you, which is far more intimate and achievable than going to see your favourite artists if that’s even possible. I’m less convinced with power amplifiers, but my particular power amp choices are rather ‘meaty’ and likely require a larger and more powerful Power Plant.

I can see why AC regeneration put PS Audio so firmly back on the map. The results it delivers with the P5 is a high value means of getting the most out of a decent system. They used to say spend ten per cent of a system’s cost on cables; I’d say you should spend even more on getting the mains right. It’s the crux of high resolution audio.


Technical Specifications

Output: 1250 VA

Features: Surge protection

Spike protection

Regulated output voltage

100% regenerated AC

Integrated oscilloscope

THD meter

Control over the web or network

Adjustable output voltage

Dimensions: W 430mm H  115mm D 360mm

Weight: 24kg

Price: £3,000

Manufacturer: PS Audio

Tel: +1 720.406.8946

URL: www.psaudio.com

Distributor: Signature Systems

Tel: +44(0)7738 007776

URL: www.signaturesystems.co.uk

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