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Mains conditioners

Click an image to enlarge.

Balanced mains units:
Nene Valley Audio (NVA) BMU 1000
Russ Andrews BMU 3000 MKII
Power conditioners:
IsoTek Aquarius EVO3 & Sigmas EVO3

During a recent vinyl exploration session at my home I asked a learned friend to describe his musical experience in just two words? He responded quickly…“Organic and engaging!”

After many years of listening, trial and error, I am happy with all areas related to my hi fi components, cables and much later room treatment. I even had a radial circuit with a double socket fitted specifically for my hi fi components when I moved into my home twenty years ago. The challenge now is to possibly get MORE from my components whilst maintaining the organic and engaging trait!

Balanced mains units (BMU’S), Mains conditioners, purifiers, regenerators, silencers… Like many components and accessories reportedly linked to improving your musical experience, mention any of the above to hi-fi & music enthusiasts and you will receive varying comments, advice, opinions and facial expressions. I was advised by many respected hi-fi enthusiasts “not to bother, or stay clear of A, B or C”. However, if I have learned just one thing over the last half century and a bit of my life, I have learned what works for one, may not work for another. It is a rare that a component (or scenario) is a one size fits all solution. I will invariably do the opposite of what I am advised (in the hi-fi world) and try for myself before making a decision and handing over my hard earned cash. BUT, if my findings are similar to those who advised me, I will always acknowledge their findings!

Companies such as IsoTek, Russ Andrews, PS Audio and Belkin have been championing mains conditioners and various filters for many years, however, only a few companies have extended their range to include balanced mains conditioners (BMU’S)

There is definitely a growing Balanced Mains Movement in the world of home hi fi which has been gathering pace in the last few years. Mains conditioners have also grown in popularity, however, the latter does appear to have as many fans ‘as well as detractors.’

‘Supplying your system with balanced mains offers an unrivalled way to dramatically reduce mains noise and improve the sound quality from your system – that’s why balanced mains are common features in recording studios…’ Russ Andrews

‘…The mains supply is distorted by numerous factors as it travels from power stations to be distributed throughout our homes, eroding the performance of high-quality audio and AV systems. As the electronic devices we use proliferate and the demand for electrical power intensifies, the quality of the electricity we feed our systems continues to slide…’ IsoTek

I initially contacted Airlink Transformers, Richard Dunn (NVA), Russ Andrews, Signature Audio Systems (PS Audio’s UK distributor) and Nick Poulson (Isol-8) and advised each of my existing component list. I also advised I had an open mind regarding expectations.

Thank you to Airlink Transformers and Richard Dunn (NVA). A huge thank you to Stephen Oakes (IsoTek), Russ Andrews & HI FI Pig’s Dan Worth for your continued patience and advice…

Airlink Transformers assured me their units were being used successfully by many professional recording studios and they supply toroidal transformers to ‘other’ companies who sell BMU’S. However, they could not offer a trial of any unit as they make units to order. So, after much thought and further research, I decided continue my search elsewhere.

MBL 120 Radialstrahler Loudspeakers

Nene Valley Audio (NVA) BMU 1000
My first experience of a balanced mains unit (BMU) came via the NVA 4 socket 240 volt, 1000 watt BMU. Richard Dunn form NVA was confident his 1000 watt unit was all I needed to power my set-up. Considering my Musical Fidelity M8 power amplifier is 500 watt per channel (2000 watt total power output) alone, I was cynical. This simple, but aesthetically pleasing unit collected by myself direct from NVA’s headquarters in Kent has its own built in standard cable and plug with four UK sockets ready for use. I initially utilised all four sockets on the BMU plugging in my M8 power amplifier, M8 pre-amplifier, phono stage and turntable power supply. As I had recently enjoyed John Coltrane’s commanding and spiritual tenor from the album “Crescent” (John Coltrane Quartet) on vinyl without the BMU in place, I felt this would be a great way to test and hopefully immerse myself even further within the Quartet’s message. Unfortunately this was not to be. Coltrane’s commanding tenor was almost reduced to a humble squeak and McCoy Tyner’s normally precise piano was now as vague as a politician’s promise. The overall result - a compressed lacklustre musical presentation!

Further experimentation and trial of various component combinations with the NVA BMU revealed that it worked wonders with my amplifier, preamplifier and internally upgraded Musical Fidelity A3 CD player. In fact, CD reproduction was on a level I had never heard before in my home (or most other homes or hi fi shows). Resolution, textures and depth were described by another music lover as “non-cd like!” Unfortunately, as CD is not my main source, it was obvious this BMU would not work for me as a final choice. However, I suspect this NVA 1000 watt BMU could possibly work its magic if your set-up total wattage output is within a specific range AND with a retail price of just £500, this BMU is without doubt superb value, so a 30 day trial is recommended!

Russ Andrews BMU 3000 MkII
I initially set my eyes (and wallet) firmly on the Russ Andrews BMU 1500 MkII. At £2550, this was still dramatically more costly than the NVA 1000 watt BMU, but still cheaper than the Russ Andrews BMU 3000 MkII (£3950). After my earlier experience and further discussion with the Russ Andrews team regarding my components, I was advised to try the BMU 3000 MkII!

Prior to delivery, the BMU 3000 voltage will be factory-adjusted to your domestic mains voltage for optimum efficiency. Russ Andrews send a voltage meter to enable 48 hour monitoring of the mains within your property. Once an average reading is obtained, the BMU is calibrated. ‘This is not user-adjustable but can be adjusted free of chargeback at the factory if the need arises – for example, if you move house.’ Russ Andrews

First impressions after delivery of this unit... “No need for me to visit the gym today, I have just completed a lower back workout carrying this unit from the front door to the living room.” This dual transformer BMU is presented within its own heavy duty hardened plastic flight case and weighs in at a sturdy 22kg! As the BMU 3000 does not have a built in mains cable to connect to the wall, I requested the use of Russ Andrews’ Powerkord 300 (a previous experience review winner). This is supplied at an additional cost.

Russ Andrews BMU 3000

This BMU has five UK sockets available. For consistency I initially utilised four sockets with the same combination as before (M8 power amplifier, M8 pre-amplifier, phono stage and turntable power supply). Once this BMU had run-in, I was able to hear (and feel) the transformation in the musical presentation overall. What started out as a brittle, harsh and tiring assault on the senses, slowly metamorphosed into the most articulate, smoothly detailed and deeply emotional connection to music of all genres. AND all this from my preferred source ‘vinyl’!

It was important to ensure I was actually falling in love with the improvement in the musical presentation and not just subconsciously relieved to hear music minus the harshness during the run-in process (or compression from the previous NVA BMU during vinyl playback). I had not listened to music through my system connected to the ‘standard mains’ for some time, so a quick A-B switch was carried out at this point. As stated at the start of this journey, a friend described his recent listening experience as “organic and engaging!” I agree with his description 100%. Listening to music through my system connected directly to the standard mains was still very enjoyable, however, now it was easy to spot the missing layers and missing extra depth, especialy with the lower octaves. I was still enjoying the music without the BMU 3000 in place, but I enjoyed it a whole lot more as well as discovering more about each individual recording with the BMU 3000 in place. The BIG question is;
“Could I live without the Russ Andrews BMU 3000?”

With the Russ Andrews BMU 3000 now back in place, I continued to revisit my vinyl collection. Donny Hathaway’s “In performance” is not the greatest recording or pressing by any measure, but Hathaway’s soulful gospel yearnings transcend such technical challenges and reaches out to all at the Troubador in Los Angeles California (and beyond). I have always been able to completely immerse myself within the joyful participating audience, or ‘zone in’ to be with the man himself and wish for a “Sack full of Dreams.” (Final and favourite track on side two). With the Russ Andrews BMU 3000 in place, I get a greater sense of Mr Hathaway’s positioning and presence within the auditorium, as well as feeling just a few spiritual steps closer to the man (and his fellow musicians). With eyes closed, toes tapping, I feel even more involved in this momentous performance than ever before.

I continued to explore other vinyl favourites, such as Rachmaninov’s “The Four Piano Concertos / Rhapsody” Vladimir Askkenazy – piano, London Symphony Orchestra conducted by André Previn (Decca). Again, I was struck by the greater depth as well as greater orchestral space. Askkenazy’s piano position and key strikes were also clearer and more precise with the BMU 3000 in place.

For many years CD has just been a ‘convenience source’ for me. I have attempted to sit in my listening chair for longer than ten minutes with any CD playing, but often failed. I have listened to various CD players in various environments over the years with multiple price tags, but always walked away feeling cold. After my positive experience with the NVA BMU, I was eager to hear what would happen to CD reproduction with the BMU 3000 in place.

I was not disappointed. Kurt Elling’s rich baritone from the album “nightmoves” combined with beguiling bass interplay with past collaborator Rob Amster on “The Waking” was nothing short of magical! Depth, detail, vocal textures and realistic individual instrument separation, combined with that ‘non-cd like’ presentation from a cd player I had almost given away a few months ago. The big test is if I felt impelled stay in my listening chair for longer than ten minutes? Well, I can confirm, six CD’s later… I only actually moved to change CD’s. I have become so involved with my CD collection, I probably would not get up to answer my front door if Jenifer Lopez rung my doorbell…
‘well actually, the last bit is not quite true..!’

Russ Andrews BMU 3000

I have to confess - I read two reviews on the Russ Andrews BMU 3000, as well as reading the info provided by the Russ Andrews newsletters prior to taking delivery. I shrugged my shoulders at the reports of various improvements to reviewers’ listening experiences and I winced at the price tag.
Can I live without the Russ Andrews BMU 3000? At this point, the answer is an emphatic “NO!”


IsoTek Aquarius EVO3 & IsoTek Sigmas EVO3 mains conditioners

(These units have also been described as mains filters or / and mains purifiers).
The Aquarius EVO3 is IsoTek’s best-selling unit with a retail cost of around £1500. The Sigmas retail price is approximately £3200.

Before listening to my system with the Aquarius EVO3 or Sigmas EVO3 units in place I went back to basics. I reluctantly removed the Russ Andrews BMU 3000 and returned to standard mains for some time. This would help to insure I was comparing the musical presentation to standard mains only (for now)!

IsoTek Aquaruis EVO3 &  Sigmas EVO3

Both Aquarius and Sigmas have six sockets each available for use. Two sockets (16 amp) in the red coloured panel area for high powered components (amplifiers). Four sockets (10 amp) in the black panel area for other components such as pre-amplifier, CD player or DAC. Power switches for each unit are placed underneath the bottom panels which help to keep each unit aesthetically pleasing to the eye.



IsoTek Sigmas EVO3

The Sigmas EVO3 front panel houses a digital display highlighting either the incoming voltage to your home, or the (THD) total harmonic distortion on your mains (before filtering). The display data can be switched via small black buttons on the lower front panel (one switching the display off).
Both power conditioners took just over a week to run-in, settling down and getting past the brittle and harsh presentation.

Utilising four sockets with the same combination as before (power amplifier, pre-amplifier, phono stage and turntable power supply) I found the Aquarius had little impact on my musical experience. After trying various combinations (disconnecting amplifier, connecting CD player and / or phono stage etc) without much impact, I decided to concentrate on the Sigmas EVO3.

IsoTek Sigmas EVO3

It was intriguing (for a while) to watch the varying voltage changes throughout the day on the Sigmas digital display. The voltage entering my home varies from 239V – 249V. The THD (total harmonic distortion) also varies depending on time of day (less in the morning) increasing when more electronic items are switched on around the house (and my neighbour’s house). The THD also increases depending which source I am using. Using my CD player seems to increase harmonic distortion into the mains supply. I tried to search for more information regarding THD and what figure relates to high distortion. IsoTek do not provide any information or documentation and I was unable to find anything more on the net. Time to listen to music…

With the Sigmas EVO3 in place, I could definitely hear a ‘difference’ in the presentation. However, it was not immediately clear if the difference was as an improvement!

Just as with cables, interconnects or any other addition to your system, you not only need to decipher what the addition has added to the musical presentation and listening experience, but just as importantly, what the addition has taken away!

For many years I have received positive feedback from viewers and friends who either own IsoTek conditioners, or have experienced IsoTek’s conditioners at various hi fi shows. One viewer commented “… the Aquarius is the most significant non hi fi component upgrade he has made to his system to date!” In fact, it was this above comment that encouraged me to start this ‘mains experience’ journey.

I continued listening to various recordings on vinyl with the Sigmas in place and noticed the musical presentation was less forward with a slightly wider soundstage than what I was used to when my system was directly connected to the mains supply. The same occurred when listening to CD. This experience was neither negative, nor positive at first, though I found my attention and focus began to wonder as time passed. I began to experiment with various combinations (as before). I even attempted to use the IsoTek Sigmas EVO3 in conjunction with the Russ Andrews BMU 3000 (Connecting amplifier/ pre-amplifier and source components across both units). This did not produce a tangible difference, or any favourable listening experience benefits. The best and most pleasing result came when I used the Sigmas with a small pair of ‘very cheap’ bookshelf stand mounted speakers for a short period (instead of my MartinLogan Scenario ESL’s). For some reason the soundstage widened substantially as well as an overall improvement in clarity, focus and note decay.

Once my MartinLogan Scenario ESL’s were back in place, I decided the Sigmas EVO3 was not for me!

As you may already know, hi-fi, components are not a ‘one size fits all’ situation…

The Sigmas EVO3 is by no means IsoTek’s most elaborate mains conditioner. IsoTek have a variety of even more sophisticated units, not to mention power cords and audiophile-grade connectors. Results and listening experiences will always vary. Perhaps I will have the opportunity to try another IsoTek power conditioner (though I suspect my bank manager would warn against this)!

Russ Andrews BMU 3000


I purchased the Russ Andrews BMU 3000 (with Russ Andrews’ Powerkord 300) and placed the unit on a specifically designed shelf at the side of my system for ideal mains cable access.



Russ Andrews BMU 3000

I continued my BMU exploration and was able to acquire another specially designed 2500 watt bespoke unit with a private designer. This Special Edition BMU with my personal logo now powers my Rel T5I subwoofer and has further fine-tuned both lower (and surprisingly) top end frequencies. Bass is even tighter and more articulate (especially double bass). Though some may see this improvement as subtle, my ears, soul and wider smile believe this addition is worth it. My listening experience has improved yet again.


The overall improvements gained: Greater clarity to all areas of the musical spectrum. The human voice sounds free, less choked. (Excuse the pun). Greater depth to lower frequencies (deeper bass). Improved musical timing overall. More cohesive soundstage. Greater space and air between notes and individual instruments.

Without doubt this is the most difficult experience review to date. The cardinal rule of not making too many changes at one time was broken on several occasions while testing various BMU’S and power conditioners. Above is just a selection of the many units tested! Some changes were forced upon me (turntable breakdown & MartinLogan ESL breakdown forcing me to use the cheap bookshelf stand mounted speakers for a short time). Other changes were self-inflicted, such as changing circuit breakers from 16 to 20 amp at the consumer unit. All repairs, adjustments and changes took time to settle (run-in) before I could reasonably continue testing. One thing for sure, I have has used more combinations in the last few months than the Enigma machine code breakers during World War II, AND more power combinations than Tesla!

Complete system details:

AMG Viella V12 turntable with AMG Teatro MC & AMG reference tonearm cable
Phono stage & interconnect cables. Whest PS.40RDT Special Edition phono stage with Cambridge AudioAzur XLR cable.

CD player
Musical Fidelity A3 CD player (internally upgraded). Van Den Hul The Second Analogue Interconnect cables.

Musical Fidelity M8-500S power amplifier with Musical Fidelity M8PRE preamplifier
Luminist Revision Poseidon XLR balanced cables.

Martin Logan Scenario hybrid electrostatic speakers. Chord Legend speaker cable.
REL T5i subwoofer.

Quadraspire Q4 EVO turntable wall bracket. Quadraspire Q4 EVO 4 tier shelf.

Robin Francis
© Michael Valentine Studio
April - May 2019


Mains conditioners



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Russ Andrews NVA IsoTek

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