Hardware Reviews

Puritan Audio Labs PSM136

Puritan Audio Labs PSM136

Mains power; can’t live with it, can’t shoot it! Now that most consumer electronics are run on switching power supplies and every home has a wireless network, the power is as polluted as the Yangtze river (but hopefully not as wet). Audio equipment manufacturers attempt to minimise the problems that this introduces but there’s only so much they can do without making products prohibitively expensive and large. Some like Living Voice have created substantial rechargeable battery supplies to get around the problem but for those of us with less space and money to spare the answer lies in some kind of conditioning or filtering. I have had great results with various types of mains cleaners and regenerators, and ground cleaners for that matter, CAD’s Ground Control for instance does wonders for the timing and resolution of most systems.

So when I came across Puritan Audio Labs at the Bristol Show I was interested to hear what their solid looking products could do. Puritan is based in Henley where Mike Lester runs a company that specialises in switching power supplies, so he knows what the problem is! Puritan makes a power cable, a strip purifier and a Studio Master Purifier, the PSM136 is as the prefix suggests the latter. It has six 13A outlets set at an angle along the back panel and a single 20A mains inlet for which a Puritan power cable is supplied in the box. The sockets have a flap cover that makes them look industrial and makes it a little fiddly to insert your plugs, but so long as you don’t do this on a regular basis is not an issue. Each outlet has its own fuse protection, which Mike considers the least intrusive way to protect the conditioner, and preferable to a thermal cut-out. You can get a fuse free alternative with heavier coils for £1,450.


PSM136 Inside


The filtering consists of a spike clamp or suppressor for power spikes above 1000V, putting this any lower apparently undermines sound quality, so this is only for really nasty jumps in the incoming voltage. There are two stages of filtering for differential mode interference, that is noise in the power supply created by switched mode supplies etc, multiple shunt capacitors tuned for different frequency  bands on the input and big inline sink chokes. For noise in the air (RFI) it has common mode chokes on the input and the same on each output, effectively isolating them from one another. DC blocking is provided by 30 capacitors, which is a lot of caps but does mean that each has an easy time of it and should therefore last longer than caps that have to work harder. Each output is refiltered for both types of interference and the earth is given a “light dusting” of filtering as anything heavier would compromise safety, the six earths are starred together and this point can be accessed with the binding post on the back of the box.

The casework is solid but not especially fancy, given that this is not a box you will have to look at or interact with it doesn’t need to be pretty, but the aluminium front and rear plates make it look neat enough. It’s also quite shallow so when the outlets are at the back of the rack you can’t really see the front unless you try.

Sound quality
The first piece of kit I tried was the Plinius Hiato integrated amplifier, a pretty powerful 300 Watt amp. Connected to the mains via the Puritan the highs got crisper and cleaner, the backgrounds darker and the clarity clearly improved to the point where fingers sliding on guitar strings appeared from a track that they were previously hidden in. The various elements within Kraftwerk’s Tour de France were better separated and there was more contrast between voices and drums. The usual problem with mains conditioners is that they restrict dynamics because the amp can’t get enough current and here there was a slight restriction on bass extension and resolution with the very deep pulse of ‘Elektro Kardiogramm’. Connecting a Microgroove+ phono stage to the conditioner brought out reverb in the bass line, enhanced three dimensionality and again provided better separation, this time accompanied by greater musicality. Adding the power supply of an SME 20/3 turntable to the roster brought about a small improvement in timing and detail resolution with the same increase in separation of notes. With another turntable, the Rega RP10, the Puritan adds depth and air around voices and instruments while the timing becomes a little more precise both as a result of a clear reduction in background grunge, all of which makes for a more sublime sound.


Puritan Mains Lead

With another amplifier, the Marantz PM-10, which has what the company describes as an “analogue switched mode” power amp section, so it’s Class D. This gained focus and precision as well as better timing and silkier highs when powered via the Puritan. It did however suffer from a shortfall in bass power much like the Plinius. In truth there are very few conditioners that can be used with power amplifiers, I have only found one (Isotek Super Titan) and it costs more than most power amps and is bigger too. But if you want finesse then the Puritan certainly provides that, and in the AVM CS 8.2 the trade off was worth giving up some low end grip for. With this all in one high end integrated the Puritan produced extra substance in the sound, making it more fluid and interesting, in fact it became downright compelling to the extent that I got quite carried away by the music. Plugging it back into the wall the image lost focus and the timing became blurred, this was not a subtle change. I also tried Rotel’s RCD-1572 CD player and got a far more easy to enjoy sound, there was a coarseness when it was connected directly to the mains that disappeared to allow a more relaxed and better timed sound when the conditioner was in use.

These results repeated themselves with most of the electronics I tried, all of which gained clear improvements except power amps. Results will vary with location of course, you may be lucky enough to have relatively clean mains power but if you’re in an urban area that is sadly very unlikely. In the context of any revealing system the Puritan PSM136 is a great value upgrade that’s well made and sensibly priced. You get slightly better results with a well designed mains regenerator but will have to pay three times as much for nearly as many outlets. Puritan have done a great job in building a solid and powerful weapon with which to combat the evils that beset mains power in the home today, if you want to know how good your system really is I recommend you investigate.


Type: multi outlet mains power conditioner
Number of outlets: 6x 8 amp
Type of outlet: 13 amp UK socket with sprung cover*
Power inlet: IEC 20 amp
Differential mode filtering
Common mode filtering
DC blocking
Internal wiring: OFC copper with PTFE insulation
Surge protection: 30,000 amp
Star earthing
Dimensions HxWxD: 110 x 430 x 230mm
Weight: not specified
Includes 2 metre 20A input lead
*available with all common outlet types

Price when tested:
Manufacturer Details:

Puritan Audio Laboratories
T 44 (0)1491 680444


Power conditioner


Jason Kennedy

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