Connected-Fidelity AC-2K Reference balanced power supply, Six Star distribution block & Unity Power Two cables
We all know how important it is to choose the individual components of our systems carefully, usually with protracted listening tests at a retailer and in our homes. But a system is more than just a turntable, CD player, streamer, amplifier and speakers. There are other elements that can also affect overall sound quality significantly and that I suspect are often treated as an afterthought. Interconnect cables, mains distribution blocks and filters, isolation supports and speaker cables all have a role to play and need to be considered every bit as carefully.
The quality of mains supply varies according to your location and poor mains can hold back a system’s potential. When Connected-Fidelity’s Michael Osborn and I got into a conversation about this, I was intrigued by his AC-2K balanced mains power supply and Six Star star-earthed six-way mains distribution block and knew that I would have to satisfy my curiosity by listening to them at home.
Balancing act
Many of you will be familiar with the concept of balanced interconnects, where there is an additional signal wire that carries an inverted version of the signal, which allows noise picked up along the way to be cancelled out through polarity inversion. In a similar way, the AC-2K has a dual-tap transformer producing two voltages, one identical but out-of-phase with the other, whereby any noise picked up should be cancelled as it is in balanced interconnect cables.
Connected-Fidelity say this helps the transformers in your system components work more efficiently, eliminates any AC/DC noise often found on the home mains earth line, and means that RF noise is not picked up on your power cables. These benefits may explain why balanced power supplies are often found in recording and radio/TV transmission studios.
The AC-2K has a non-magnetic case that is substantially damped, anti-surge protection built in and audiophile quality, gold-plated input and output sockets. Components, including the transformer, are cryogenically treated (this improves the metal’s internal crystalline structure) to ensure maximum power delivery and speed. Osborn says that after cryogenic treatment the transformer performs like a much larger non-treated transformer. It is mounted on a non-magnetic platform that isolates it from the casework and your room and uses hybrid copper/silver UP-OCC internal wiring. The 16A IEC input and 13A output sockets are both gold-plated. Twin RCBO electronic trip switches on the balanced output monitor overload, short circuit and earth leakages. The unit is recommended for use with amplifiers up to 1,000 watts.
But will this balanced configuration bring the same sonic benefits as it does in interconnect signal cables? This is what I was keen to find out. For this test, I used the AC-2K in conjunction with Connected-Fidelity’s Six Star six-way, star-wired distribution block. The Six Star does not contain any filtering and is intended for use with the AC-2K balanced power supply.
Star quality
Star wiring means that each component is connected to an identical direct power supply and earthing rather than being in series. The diagram shows the star wiring configuration used on the Six Star. All the wires from the output sockets are connected to one star point for live, neutral and earth, as opposed to the conventional approach of parallel or series wiring that connects the output from one socket to the next.
In the Six Star, at each of the star earth points, rather than attempting to solder together multiple wires, Connected-Fidelity use a small busbar, connecting all six outputs to the input cable in an airtight, non-soldered connection. To improve performance further, the copper busbar is also cryogenically treated.
The chassis of the Six Star is made from non-magnetic stainless steel with a Perspex body holding the output sockets, it sits on four soft rubber feet to isolate it from external vibrations. The sockets themselves are high-quality items sourced from ABL in Germany, while the C19 IEC input socket is from Furutech in Japan. When not used with the AC-2K balanced power supply, Connected-Fidelity recommends the use of a wideband RF filter, an option that they can offer.
Connected-Fidelity also supplied me with five of their Unity Power Two mains cables. These use 3.3sq mm conductors made from 65 wound strands of tinned, high-purity copper cable, sheathed in a thermoplastic resin, while the earth wire is made from a UP-OCC silver/copper hybrid. The individual live, neutral and earth strands are twisted together so that the individual strands in each wire lay in line with each other in a ‘rope weave’. This, says Connected-Fidelity, also provides some degree of RF isolation and line noise suppression without the need for further screening or filtering components. All of the wires and conductive plug parts are cryogenically treated – a process that is accepted as improving the ductility and workability of the metal and that Connected-Fidelity says improves power performance.
The Unity Power Two cable comes in two versions. The 2S is for source components and preamps, while the 2P is for integrated and power amps and has six conductors compared with three in the 2S. Both have a double-layer outer sleeve to isolate the cable and the mains plugs are a Furutech IEC and MS HD Power 13A plug, fitted with one of the company’s C-F fuses. These use silver alloy fuse wire and copper end caps, both cryogenically treated, which, says Connected-Fidelity, allows the wire to be better bonded to the end caps. The end caps are meticulously cleaned before fitting and there is a resonance-damping shield over the fuse case. They are also subjected to an ultra-high voltage at a very low impedance, which Osborn tells me improves sound quality, although it is not generally understood quite why this works.
Does it all pay off?
You can see that a lot of thought and attention to detail has gone into every aspect of these products to ensure that the mains you feed to your system is the best it can be. But will it improve the sound of your system? Well, we get to the point now where we find out.
I used the Connected-Fidelity AC-2K balanced power supply and distribution block and leads with my Audio Note CDT-Five CD player and DAC Five Special, Audio Note TT3/PSU3/AN-S9 step-up/Arm Two/Io1 cartridge equipped turntable, Russell K Red 150Se speakers, using two different amplifiers. On the one hand, the super-high-end Linn Klimax DSM pre/streamer/DAC and Klimax Solo 800 power amps (£100k more or less), and on the other a Chord Electronics Ultima Integrated amp at around £8,500. I was curious to see if the C-F setup would make worthwhile improvements with both amplifiers.
I kicked off using the Linn amps and compared the C-F setup to a standard commercially available distribution block and standard IEC mains cables, with both fed from the same mains wall outlet.
I started with a simple track, the beautiful ballad You Bring the Sun Out from Randy Crawford’s Secret Combination album. I was immediately bowled over by how much more real, open and human her voice sounded using the AC-2K setup. Without it, her voice was smaller, less expressive, while on the C-F setup there was much more space around her and her voice was much cleaner. The piano on the intro was also much better defined on the AC-2K setup with more leading edge definition, body and space around it. On the chorus, the bass line, cymbals and keyboards were also better separated.
This whetted my appetite for more and so I spun up guitarist Peter White’s superb cover of Johnny Nash’s I Can See Clearly Now from his Groovin’ album. Once again, it took only a few bars and the first few notes of White’s guitar to hear how much more open, detailed and dynamic it was on the AC-2K. His guitar was more solid and real and I could hear better how each note was played. Percussion was more sharply defined and detailed, while the bass line was tighter and more tuneful. The staccato rhythm of this track came across more clearly on the C-F setup and when I reverted to the standard mains block, the sound collapsed and became smaller, with instruments less incisively etched.
Moving things up tempo, I played No One Emotion from George Benson’s 20/20 album and was impressed at how the AC-2K setup really drove the track along with the bass and drum elements sharper, tighter, better defined. The track really motored and when I swapped to the standard mains block, the pace was slower, the bass line not so full or tuneful and Benson’s vocals more recessed and not as open and expressive. You could also really listen into the complexities of this lavish arrangement better using the C-F setup.
But would the differences be as pronounced on an amplifier one tenth the price of the Linn? Switching over to the Chord Electronics Ultima integrated, I played Lo Siento Mi Vida from Linda Ronstadt’s superb Hasten Down the Wind album and again the AC-2K setup left the standard mains block for dead, with her voice sounding more real, defined and articulate with much more space around her. On the intro, it also differentiated the guitars of Andrew Gold and Waddy Wachtel better. The pedal steel too was better defined and easier to follow, while the bass line was deeper, tighter and more agile. The victory was decisive again for the AC-2K setup and subsequent tracks from Miles Davis to ZZ Top confirmed as much.
A clean sweep
I must admit that the Connected-Fidelity AC-2K and Six Star/Unity Power Two setup delivered far more than I was expecting. The differences between it and the standard mains block were huge and musically very significant. You could simply hear far more of what was being played and how, with instruments taking on their proper context in the mix. Vocalists were more real and focused with more space around them.
You could easily spend £4,500 and more on speaker cables. But when I have compared speaker cables, they often add a tonal balance element along with any other sonic improvements. Some are brighter than others, some have more bottom end weight, some less, some may be slightly recessive, while others are more forward in their presentation. So speaker cables need to be matched to the particular system. But with the C-F AC-2K balanced supply and distribution block, the differences transcend mere tonal balance and what you get is a real musical improvement across the entire frequency spectrum, which should be the case in any system. I tried it with two amps and even substituted some different speakers and this still held true.
What this showed me is that the quality of mains fed to your system is important and that it is money well spent to make sure it is as good as you can get it. I recommend this Connected-Fidelity setup wholeheartedly.