Isol-8 Powerline Extreme AC power distribution block
When I first started out in hi-fi, if someone suggested shelling out a grand or more on a fancy mains block, I’d have laughed at them. Things have moved on from there though, and we now accept that to get the best out of a system, you need to address all areas, from the mains supply to the interconnect and speaker cables.
Nic Poulson of Isol-8 knows well how important optimising your mains supply is and his company offers a broad selection of power conditioning and distribution products that are designed to do just that.
He started out as a BBC sound engineer but left to set up Trilogy in 1990, which I imagine you will know from their excellent amplification products. He has always believed in the importance of tackling power supply problems and believes they have been largely misunderstood. He set up Isol-8 in 2000 to develop products to help deal with poor mains supply and distribution.
The problem
What’s wrong with the mains? Isol-8 say that your AC supply is generally contaminated by other connected appliances – DC components, harmonic distortion and radio frequency interference introduced to the grid by other users. The power supplies and diode rectifiers in your hi-fi components also add their own noise to the mains, which Isol-8 refers to as ‘cross contamination’.
Because everyone has different requirements, Isol-8 offer a large number of options and in their Powerline range there are five models. The most basic Power Plus (£725) has an earth line choke to deal with any RF in the system earth and signal ground, and a single pole shunt filter to deal with any general noise. The Ultra (£850) is fully power conditioned and surge protected and has a high-current outlet for loads such as amplifiers. It also features what Isol-8 call ‘transmodal filtering’ (see explanation later) to attenuate transmitted and induced noise without dumping it to ground.
The Axis model (£900) sets out to cure any DC voltage on the mains that can cause transformers in equipment to hum and also degrade performance. It also features surge protection, but does not have transmodal filtering. The Powerline Extreme (£1,200) seen here, combines all of the features in the Ultra and Axis – surge protection, DC blocking, high-current output socket and transmodal filtering.
Filtering
Nic Poulson set out to tackle the different types of noise that can contaminate the AC mains supply to your system. His Powerline distribution blocks have one filter to deal with any contamination of the mains coming into the unit, then (except for the Plus and Axis models) use additional filters to deal with the noise generated within the system that passes from one component to another. These transmodal filters deal with what Poulson refers to as differential mode noise (generated from circuit elements within the load or source itself) and common mode noise, which can be picked up from transmitted radio energy and broadcast or wi-fi transmitters.
Poulson explains that common mode noise can be dealt with using a common mode inductor, which uses phase cancellation to attenuate unwanted noise. But it only deals with common mode noise. Differential mode noise passes straight through it. He says that many mains conditioners on the market use shunt elements without series inductors to divert the noise to earth, which then pollutes the earth instead. Isol-8’s transmodal filters do not do this and are said to filter both types of noise while keeping the earth clean.
The Powerline Extreme also features DC blocking. DC can get on to the mains from items such as dimmer switches and computer power supplies. This, says Poulson, means that the AC waveform we receive can be clipped, distorted and asymmetric. He adds that the AC transformers in audio equipment cannot tolerate significant DC elements, which can saturate the magnetic circuit. The Isol-8 circuit is claimed to rebalance the energy axis of the mains waveform, blocking DC without restricting effective current flow.
The Powerline family all use an anodised 6mm thick CNC-machined aluminium top plate that is non-magnetic and non-resonant. The power outlets are high-quality 13A types with hinged covers that conform to IP54 and the input IEC socket is rhodium-plated. Internal wiring is silver-plated copper with PTFE insulation. The Powerline Extreme has four standard AC outlets plus one high-power outlet with a high-current shunt filter, intended for loads such as power amplifiers.
Power to improve
In the hi-fi world, people often condemn things as smoke and mirrors, usually because they do not fully understand the concept behind certain products. But I have tried many mains conditioners and distribution blocks and cables and have found them to brings significant improvements to sound quality in my system.
Everyone’s mains is different, of course. You may live in the middle of nowhere where the mains is quite clean, or in a town or city where it is most likely not so clean. Either way, it is well worth trying an Isol-8 block to see what it can do for you.
To check what the Powerline Extreme has to offer, I hooked it up into my system at home, which currently consists of Audio Note source components (TT3/PSU/Arm Two/Io1 turntable/arm/cartridge, and CDT Five CD transport with a DAC 5 Special) with Fyne Audio Vintage 10 speakers. I used two amplifiers during my listening to check consistency of results – a Chord Electronics Ultima integrated amp (transistor, 125W) and an Audio Note Meishu Tonmeister (valve, 8W). Speaker cables were Audio Note copper, bi-wired.
To connect the Isol-8 Powerline Extreme to the wall I used a standard IEC cable. From the block to the components I used Musicworks Revive Ultra II cables. Isol-8 also make a range of Isolink cables, but these were not supplied for this review. To serve as a benchmark and assess the Powerline Extreme’s value for money, I also had to hand another well-respected mains block at around the same price (actually, slightly more expensive).
I started though by comparing it with a standard four-way, non-switched mains distribution block such as you would buy from your typical electrical retailer. The first track I tried was No One Emotion by George Benson. Switching to the Isol-8 block, it was immediately clear that the driving synth bass line was deeper, tighter, more melodic and drove the track along much better. The Rhodes piano had more sparkle and presence and all the facets of this lush production were laid open to better appreciate their contribution to the whole. Benson’s voice was cleaner and more open and Michael Sembello’s blistering guitar solo was more open, raunchy and you could really hear his fingers fly.
The benefits were also cut-and-dried using guitarist Larry Carlton’s Discovery album. The Isol-8 blew the standard DIY store block into the weeds. Carlton’s guitar was more open and articulate and the bouncy, sinuous bass line that underpins the track was much tighter, deeper and more rhythmically compelling. Is the Powerline Extreme worth the extra money? I’ll say it is.
Battle of the blocks
Next I tried the Isol-8 against its similarly-priced competitor, which by the way also blew the standard mains block into the weeds in its own right. Using the track I Can See Clearly Now by guitarist Peter White on CD, I felt his guitar had more bite on the Isol-8 and you could hear just how he shaped every note. Percussion was more sharply focused too and the reggae-style, lilting bass line was tighter and moved better. I could also pick out White’s accordion backing more easily. The other block was good, but the sound was more forward and the Isol-8 simply put more space around all the musicians.
For some vocals, I spun up Canadian guitarist/singer/songwriter Stephen Fearing’s latest CD, The Empathist. Fearing’s voice was more open on the Isol-8 and you could hear better the inflections and touches that make his vocal style so distinctive. Piano too was more open and detailed with more space around it and the dobro had more leading-edge detail and was better voiced. Again, the other specialist block was more forward and did not separate out the individual elements as well. I also quickly switched back to the standard block and the difference was night and day!
A must-have improvement
What this test of the new Isol-8 Powerline Extreme shows is that a good mains conditioner/distribution block is a vital part of a hi-fi system and you should consider it as carefully as you would, say, speaker cables. In my system, the Isol-8 Powerline Extreme impressed me tremendously. The improvements it brought to dynamics, detail and musical integrity were significant and well worth having. It improved every track I played whether on CD or vinyl and the improvements it gave over a standard superstore-sourced block were significant. It was night and day, while the Powerline Extreme also compared well with another similarly-priced audiophile block, and I must admit I preferred it. I recommend the Powerline Extreme wholeheartedly. Give it a try. You’ll wonder how you ever lived without one.
Pros
Excellent at reducing mains-borne noise, resulting in noticeably cleaner and more open sound.
Improves bass performance with greater depth, control and rhythmic drive.
Enhances clarity and separation, making individual instruments and vocal details easier to hear.
High-current outlet designed specifically for power amplifiers avoids current restriction.
Solid, high-quality construction with thick CNC-machined aluminium top plate and quality components.
Performs clearly better than a standard mains block and competes strongly with similarly priced audiophile alternatives.
Cons
Relatively expensive for a mains distribution block at around £1,200.
Benefits may vary depending on the quality of the mains supply in a given location.
Full performance may require additional investment in quality power cables.
Only five outlets, which may be limiting for larger systems.