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Positive Feedback ISSUE 33
september/october 2007


silver circle audio

Pure Power One 5.0

as reviewed by Francisco Duran







DALI Euphonia MS4.

Antique Sound Labs MG-SPM25DT monoblocks, Canary CA-301Mk-II amplifier, and Reference Line Preeminence lA passive and Canary CA-601Mk-II preamplifiers.

NAD T531 and Antique Electronic Supply CD-1 (temporary) CD players, and a Taddeo Digital Antidote Two.

Either JPS Superconductor+ and FX interconnects and a double run of JPS Ultraconductor speaker cables, or Analysis Plus interconnects and Oval 12 speaker cables, and Monarchy and various DIY AC cords.

Balanced Power Technologies BPT 4SE, Brick Wall Series Mode Surge Suppressor, Audio Prisim Quiet Lines and Noise Sniffer, Vibrapods, Black Diamond Racing Boards and cones, Final Labs Daruma-3II Isolation Bearings, various ferrite rings, Target rack, Yamaha KX-380 cassette deck, custom made wooden cable lifters by Mr. Clark senior, and all the NOS tubes I can afford!


Has it been that long since we started using expensive vibration products under our equipment and silver contact treatment on everything? Has it been that long since we plugged every piece of gear we had in our systems in any available receptacle our generic power cords would stretch to? Remember that extension cords have always been a no no! Without going into an audio history lesson, products like PowerWedge, TrippLite, and Tice were the first products to not only help untangle our old black stock power cords but brought the added benefit of clean and protected power to our systems back in the day. Well like the ad used to say, "We've come a long way baby!" Series mode, parallel mode, balanced power, and passive are the application of today's power line conditioners. As my old Uncle Irvine used to say, "Oy Vey!" Well not really, I don't have an Uncle Irvine. But I'll say Oy Vey! The advent of AC conditioning developed from a necessity of convenience to a serious component in its own right and companies such as PS Audio, Shunyata and Balanced Power Technologies - to name just a few - have emerged as household audiophile names in the power line conditioning stakes. You can now add Silver Circle Audio to that noted company.

It also seems that PLCs are as common as interconnects and speaker wire and everyone involved in wire manufacturing is making a power line conditioner and putting one out on the market—or vice versa. Have you tried wire or a PLC from every manufacturer out there? No? Well, neither have I! Enter Silver Circle Audio. Enter David Stanard of Silver Circle Audio. The rumors are true. The Silver Circle Pure Power One. 5.0 is huge. This 65 plus pound isolation transformer with a 5 kva transformer to handle even the most power hungry amps, is not only large in size, but a beauty to behold. With its solid wood sides and anodized aluminum chassis it makes a striking statement for an isolation transformer. Other features include 10awg silver plated copper "power plus wiring", and a hand built EMI/RF filter along with custom hand built soft start circuit with 30 amp rated relay. This unit is built with a 50 amp terminal block. Receptacles of choice are available on request …those in the review unit were the Furutech's latest 20-amp receptacles, the FT-D20A (G). The power cord used was the Silver Circle Vesuvius, which uses Wattgate's gold 330i and 350i HC connectors. The 5.0 has extensive internal vibration damping and is said to be "mono block friendly". OK you say, many other PLCs have similar features and parts used in their construction. Yes, but as my old Aunt Josie used to say, "The secret is in not the ingredients, but in the way you mix them up." And yes I did have an Aunt Josie!

Not to belabor the point, but this unit is not small. This is no reviewer's cliché when I say to work out the positioning when considering a purchase. Even though my den is a 12 x 20 foot room, it fills up quickly. I placed the 5.0 on the right side of my four-tier rack, behind the speakers. This is the spot I usually go to make changes to my system, be they cable, component or whatever. With the 5.0 in that space, I turned into a 6'2" 269 pound contortionist. While we are on the subject of placement, it just so happened that I had some wiring problems in the receptacle that I plug my BPT 4.0SE into, and this being the very same place that the 5.0 was to be tethered electrically. After an electrician's visit and a small but significant lightning of my wallet, it was on to the 5.0.

So just how does one go about reviewing a Power Line Conditioner? In my case I positioned the 5.0 as close to my other PLC as I could, listened, switched out all power cords, powered up, and listened again. I first compared the 5.0 with the BPT 4.0SE, and then switched it for the BPT 2.0SE. I have two PLCs from Balanced Power Technologies in my system. The one thing that kept eating at the back of my mind though was the fact that whenever I switched PLCs, the fresh one would pretty much be stone cold. I also didn't want to plug both units into the same receptacle for fear of taking out a fuse in the electrical wall panel, and the other nearest available receptacle was in another room. Even utilizing a special hole cut in the wall for running wires through from room to room, I could not get the power cord to reach this plug. As it turned out the phenomenon of a cold PLC didn't have an effect on the sound. It also turned out that plugging in the Silver Circle Pure Power One 5.0 stone cold right out of the box proved a revelation in that there is a very noticeable difference between it and my regular PLCs. But more on that later.

My regular PLCs are a Balanced Power Technologies 2.0 SE and an older discontinued model, the 4.0SE. Each unit has been upgraded with ESR paper and other goodies. The 2.0SE is also quite heavy although quite a bit smaller than the Pure Power One 5.0. The 2.0SE at 60 pounds, compact with no handles is a bee-hive to move around. Add to the fact that "I ain't no twenty one years old no more either" and a session like this definitely generated some choice adjectives which were used to full effect in the aid of lifting these heavy objects. The 2.0SE has a 2000 VA. Torrid transformer, 15 amp with five double outlets. Power travels from the wall to the 2.0SE through BPT's Clairity C-7 seven gage silver-plated power cord with Shorter plugs. The 4.0SE uses four transformers each rated @500 VA and also has ten receptacles. Needless to say isolation between components should be potentially greater with the 4.0SE than the 2.0SE, which indeed this fact is borne out in the listening. The 4.0SE is the one used on a regular basis in my system. The 2.0SE has been relegated to phono preamp and turntable duties only. My phono system has been set up behind the adjacent wall to my listening room/den behind my main system. Basically I cut a hole in the wall and ran the interconnects through to my passive line stage. This isolates my turntable from my speakers quite a bit better than having the TT set up in the same room as the big Dalis. When my speakers are cranking in the other room, you can feel the wall vibrating, the turntable is not. In other words my main system is in one room and my turntable set up is in another with its own dedicated power line conditioner and very heavy dedicated stand. Hey, it is my house, I am paying for it, and I can cut a hole in the wall if I want to! This is a long and roundabout way of saying that I could not plug my turntable and phono preamp into the big Pure Power One 5.0. Bummer!

I have had no problems whatsoever with the 4.0SE powering any of my amps. I hear no compression in the dynamic peaks or flattening out or squashing of the soundstage, with the exception of the amps running out of steam at high volumes. Even though my amps are far from what you would call behemoths, they are not "flea" amps either. One 500 VA torrid handles one stereo or two mono block tube amps quite well.

If you read the ad copy of a lot of audio gear advertisements it is sometimes hard to separate the hype from the real information. On the Silver Circle website there didn't seem to be a lot of either. Aside from some basic information about each product, there seemed to be just what you needed and not more. Personally I would have liked to see some information on the proper lifting techniques of a 70 plus pound compact electronic component. But as they say. "The proof is in the pudding". If one can lift this unit or not is not the question but how it performs in ones system.

The Pure Power One. 5.0 delivered clean power to my system in spades and it did so quietly and without the slightest hint of abnormal behavior. My wake up call for work is 4:30 AM. Every morning I go into the den to dress so as not to wake up the rest of the family. As with my BPT unit the 5.0 emitted a slight low level hum. But it seemed you could only hear it early in the morning when nothing else could be heard in the house but silence. (Hear silence?) This low level hum was very slight and never did it intrude in the music making. Is this intrinsic to PLCs with huge transformers? Your guess is as good as mine. (This hum is more likely a result of DC being dumped into the AC line somewhere on the line - Ed.) I will say that I did not use any kind of vibration damping products on either of the three units such as cones, pucks air platforms or bearings. The units rested on their natural born feet on a square piece of thick MDF board.

As mentioned above, I was in for quite a surprise when I turned my system on plugged into the 5.0. From the time it took to unplug and plug everything in, turn on components, let the amp stabilize, catch my breath, make sure there was silence in the house, and finally listen, you would think I would forget what the hell I was doing. But no, this drill has been played out too many times in my house! Instantly recognizable with the 5.0 was an increased liquidity to the music across the frequency spectrum. Yes this paragraph should have started out mentioning the big reduction in background noise, and there was. But my system is already quiet and it also has a good spoonful of that liquid sound. What struck me was that these qualities were taken to the next level with ease and without me realizing that there was even room to go to the next level. It was as if a layer of background grain and haze had been stripped away that I didn't even know existed in my system. I have read about this phenomenon in other reviews but now it was happening in my system thanks to the 5.0. Of course it helped that I had one of the greatest cellist in the business to aid in the discovery of these musical qualities. Yo Yo Ma's CD, Appassionato is a collection of works recorded between 1978 and 2006. The list of guest musicians is as varied as the musical selections, including John Williams on piano, Pauqito D'Rivera on clarinet, Isaac Stern on violin and Ennio Morricone to name a few. For example on track 9, Kojiro Umezaki playing the shakuhachi sounded noticeably cleaner and the background now seemed to bring forth this flute like instrument more solidly into its own space than with my regular PLC. One also got a greater sense of awareness of this instrument's place among the other instruments. Ma's cello sounded sweet and textured with the body of the instrument noticeably coming out of the recording more easily. This texture is an increased naturalness and does not have anything to do with grain, harshness or electronic artifacts. I am telling you, this unit is slick incorporated!

Transient speed and dynamics gained a degree of dexterity and freedom of movement and dimensional breath. As in the upper frequencies, from the lower bass and slightly past to the upper bass, music was brought forth from a silent, velvety, quiet background that brought out the sweetness of my amps low end. The bass range also sounded fuller and slightly richer. It was as if the 5.0 brought out the taut, bouncy, rich and full textured aspect of bass as opposed to the tight, dry or flat sounding plunks. Believe me, bass was solid, tight and explosive through the 5.0. A spinning of Sly and Robbie's LP, Syncopation on the title track "Free Ticket to Ride" will let you know that with certainty and quickly get your attention. Another LP that is loads of fun to listen to and also displays good demo ability is Flash and the Pan's self titled album. On the cut "The African Shuffle," the bass and drum are in tight syncopation. On this album this is not so much an explosive or bombastic demonstration of bass prowess but one that shows a system or component's ability to handle dexterity over brute force. Through the 5.0 nothing was left to be desired in this area. There was a buoyancy and flexibility to the bass and drums that kept the pace light, fast and as agile as I've ever heard this track through my system. Again on two other CDs the 5.0 showed its mettle. On Anna Nertebko's Russian Album and Bryn Terfel, Tuitti Mozart, both on Deutsche Grammophon, their vocals were more than the center of attention. The 5.0 brought out both the subtle vocal articulation, power and beauty and dynamic emphasis with ease. The silent and very clean background of the 5.0 was paying off in a big way here.

Could I have heard this the same way through my BPT 2.0SE? The answer is yes but with a twist. The BPT 2.0SE lets bass come through that is very powerful, deep and taut. In fact as far as solid and deep bass output is concerned, it noses ahead of the 5.0 in this regard in my system. But bass does sound a bit drier and tighter. The big trade off though is in the upper octaves. From the mid range up to the treble there was a noticeably silver sheen that made the music bright. There was also an emphasis on sibilance. What was worse was that from the mid range to the lower treble the music took on a brighter, flatter and more sibilant character similar to early digital. This was driven home when playing Little Milton's CD, For Real. This CD was used for the Art Audio Quartet review and the Silver Circle 5.0 just happened to be powering the Quartets. So we might as well economize huh? On track six, any word with an "S" in it sounded more silvery and sibilant through the BPT 2.0SE. The overall musical presentation sounded smooth with that tight, solid bass. There was also a very open and dimensional stage with solid images populating it. But from the mid range on up it was a no go. Remember when I said I did some fast switching and I thought a cold unit would not perform as well as one warmed up? Well I let the BPT 2.0SE warm up for two days and it sounded worse than when it was cold. Strange as it seems when I reinstalled my BPT 4.0SE the sound took on a dramatic shift towards the Silver Circle 5.0 unit sound wise. The 4.0SE is not quite as clean or transparent as the 5.0. Dynamics are not as explosive as with its bigger brother, the BPT 2.0SE. But it went a long way to alleviate the cold, silvery sheen and brightness of the 2.0SE. Go figure. Is the 2.0 broken? I don't know. I have great respect for BPT products but a trip back to the manufacturer is probably in order for the BPT 2.0SE.

I switched back to the Silver Circle Pure Power One 5.0 and it was emitting clean and neutral power. It also doesn't mask a recording; good or bad. But it sounds more full, round and natural with a blacker and very silent background. The noise floor is lower than low. Instrumental timbres and tone sound more realistic with dynamics and bass that is articulate, taut and naturally textured. I have emphasized the subtle aspects of the benefits of its performance but OK, I will just say it. The 5.0 makes for one of the quietest, cleanest, grain-less, and most dynamic backgrounds I have ever heard in a power line conditioner. In a field where power line conditioners are of many varieties, the Silver Circle Pure Power One 5.0 makes an exceptionally strong showing. Its build quality, performance and aesthetics bring the music into your listening room that much more natural and enjoyable. Unlike the Ultra System fuses that I recently reviewed, this unit is not something that you can place in your shirt pocket and take home to play with. A review on one's system will require a little more effort; one that I am sure will prove to be more than worth the effort. Francisco Duran


  • 5.0 kVa Proprietary 65+ pound isolation transformer.

  • Massive black anodized aluminum chassis.

  • Furutech Gold-Plated IEC inlet.

  • 10 AWG silver-plated copper power path wiring.

  • Proprietary hand-built EMI/RF filter.

  • Custom hand-built “soft-start circuit with 30-amp rated relay.

  • 50-amp rated terminal block.

  • Comes standard with Vesuvius Power Cord (an $800 retail value).

  • 5.0 – 4 Furutech Gold 20-amp receptacles.

  • 5.0se – 1 Furutech Gold 20-amp receptacle – monoblock friendly.

  • All contacts treated Caig DeoxIT Gold for superior electrical transmission.

  • Extensive internal vibration dampening.

Pure Power One 5.0
Retail: $5000

Silver Circle Audio
web address: