I am quite fanatic about my mains. I have mains conditioners on every piece of my hi-fi, and numerous zapperators, filters, chokes and surge protection. Indeed, RABMU2for a very short time in my life I helped in the design of mains conditioners for a UK manufacturer. The question is, though, why clean up dirty mains when you can start out with perfect mains in the first place with a transformer? Indeed, Russ Andrews advise you not to mate the BMU 1000 with any kind of mains filter, and certainly not on the balanced (output) side. The Balanced Mains Unit 1000 is exactly what it says on the (plastic) tin; a balanced nominally 1000VA transformer, which splits the voltage to 115V on live and 115V on neutral, as opposed to 230V live and 0V neutral.  The advantage of this is that noise on the positive half of the signal is cancelled by that on the negative side. Having worked with balanced mains circuits in broadcasting and recording studios, I can vouch for hearing the benefits of reduced hums and buzzes. As hinted above, the 21cm x 29cm x 9cm box is made of ABS with a 10mm anodised aluminium front panel. Russ found it gave better sound quality than solely metal boxes, and which also helps keep down the weight to 9.82Kgs. This is a very heavy unit for the size and needs a sensible and secure placement, preferably not a resonant glass cabinet, because as a transformer it vibrates.

Indeed, the degree of vibration depends on matching to the house voltage. The unit is supplied as 225V, and mine hummed at 100Hz pretty badly unless I damped it on a surface such as a carpet or cloth. The hum is caused by the fact that the core laminations in the transformer are extending and contracting as they are magnetised, called Magnetostriction, and so this will RABMU1happen twice in each 50Hz UK current cycle. Because there are more windings at 250V than at 225V, less current is drawn and therefore has less flux and less vibration. It is therefore important that the primary side of the transformer is set to the same voltage as what is feeding to it, otherwise flux will increase, meaning it could get excessively hot and make noises. The good thing is that you can change the output voltage to 240V, 250V, 260V in order to reduce that hum. These are simply different TAP settings on the transformer, connected by mating a plug at the end of the brown live cable with one of a choice of colour leads with insulated sockets on them. Obviously you need to do this without the unit connected to the mains. This really is a suck-it-and-see task. Mine worked best at 250V, as my voltage supply is usually around 244V. The transformer is made using “innovative” core technology, with high quality materials to help to reduce transformer noise and DC, offering very low mains impedance and giving the most stable supply possible.  Whilst a little effort is required to get inside this unit to make these changes (7 screws), it also has a resettable thermal breaker tucked in the corner which can be pressed to reset the unit if it fuses, though perhaps this could have been on the outside, even under a flap, like in many industrial grade transformers. The unit has an aluminium metal front and is generally well made, though the supplied rubber corner feet are smaller than the lip of the metal front (see photos), and therefore of not much use unless it overhangs the platform on which you place it. For demonstration I placed the unit on Iso-pod sorbothane feet supplied by showing the feet BMU1000MissingLink Cables.

The unit came as standard without any IEC plug to connect it to the mains and surprisingly needing a 16A IEC connector as opposed to the usual 13A IEC kettle lead, not that I’d ever suggest using one of those. So, having spent £1,599, a further outlay would be needed before you could listen to anything. Lucky for me Russ sent a Powerkord-300. The 1m £240 power cord with Kimber weave and the new WattGate EVO IEC plugs is quite a sexy looking item with a thick girth, and my cat (bless him) would have enjoyed chewing away at it (as he does with all my own cables when he wants food) had I given him the chance. No, I protected both these classy looking items as I would the Crown Jewels.

On first listening even my cat sat up and listened; maybe all those extra frequencies from my Townshend SuperTweeter. I could hear a new clarity in all that I played, with pin point precision in all frequencies, not just the very highs. Cymbals in Dave Brubeck ‘Direct Cut Disc’ LP were of a new order of clarity and realism, and the trombone played by Chris Brubeck filled the room with bite and zest. Even on vinyl the greater noise floor was immediate and stunning. Music was easier to engage in, and my Krell power amp was like a stallion tamed for young children to ride. It wasn’t that it was slower, just not so impatient and with a BMU1000  1far greater authority and more open to enjoy all the frequencies. The greatest awareness of change in my listening tests was of the extended and weightier bass frequencies, even from my bass-generous Krell KPS 20i CD player. Who says CD can’t be fun. The talented Yes guitarist Steve Howe was clearer in the excellent “Masterpiece Guitars” album he did with Martin Taylor (p3 Music Ltd). In ‘Two Teardrops’ the two guitars were distinctly separated left and right with Steve or was it Martin breathing between the phrases on the left speaker, as if he were in the room with me (I wish). The double bass in ‘No Pedestrians’ was clear and extended. ‘Harpnosis’ was hypnotic in in its clarity and poise, and showed CD to be what was claimed it could be in the early eighties. A myriad of plucked instruments from around the globe knitted together with clarity and authority and I was whisked away to another world, where in other systems the track could be a traffic jam mishmash of unconnected noises. The repeated C-diminished and C-major phrase wasn’t boring and I felt I was there amongst the musicians. Turning to classical music I heard more detail in the Naxos Brahms 1st Symphony (BRT Philharmonic orchestra). Not only was stereo spread noticeably improved, but front to back detail was clearer, meaning there was better separation between first and second violins, something which can be hard to pick out. Indeed, I could even pick out edits in the recording such as at 05’52” track 5 in the Brahms ‘Haydn variations’, something I usually only detect on headphones.  Playing some of my own 24bit/96kHz recordings using basic X/Y stereo configuration allowed an even greater natural depth and accurate imaging than without the mains unit.

If I have any gripes against this product it is that it only has two outputs at the price, meaning daisy-chaining further extension blocks in order to connect more than two units, and possibly introducing RFI. Yes, there is the 1.5KW BMU1500 but this still has two outputs (though with two transformers, one for each socket) and the 3KW DMU3000 has five outputs and twin transformers, and is at £3500. For me the DMU, which ever one you decide on, is the purest way to upgrade your Hi-Fi to how it should sound. Having it connected to my own hi-fi for this review gave me nothing but smiles on my face for every second that I used it. This was the quickest, and effectively the cheapest, upgrade to my home audio, and when connected to my TV gave me greater colour and sharper definition to boot.


This might seem like an awful amount to pay for a mains double adaptor, but once you get past the fact that this is much, much more, and feed this to your prized Hi-Fi or TV, you’ll wonder why you didn’t do it sooner. It might be very expensive but the change it makes to your music and video is exponentially greater than the sum of its cost.


Sound Quality – 8.7/10

Value for Money – 8.2/10 (there are cheaper balanced mains units, but the cheapest aren’t tailored for hi-fi, nor made so well)

Build Quality – 8.6/10 

Overall – 8.5/10

Janine Elliot

How we carry out reviews.

Read more Hifi Review.

Read More Posts Like This

  • Balanced Mains Units are used extensively in professional studios and are starting to make their mark in domestic audio situations. Janine Elliot gets her life in balance and plugs in the Russ Andrews BMU 3000 costing £3599. "Reviewing cables, mains conditioners and balanced mains units is bound to irk some hifi addicts, particularly engineers.  I, like most reviewers, have suffered…

  • Russ Andrews BMU 3000 Balanced Mains Unit

    Janine Elliot recently reviewed the Russ Andrews' entry level Balanced Mains Unit which you can read all about here. Now Russ Andrews Accessories has introduced the New BMU3000 Balanced Mains Unit to provide 3kVA of power to hi-fi and home cinema systems. Working on the same principle as balanced audio signals, where the audio signal is split into two halves…

  • Russ Andrews Accessories is introducing the latest version of its BMU1500 Balanced Mains Unit to provide 1.5kVA of clean power, individually tailored to each installation. Working on the same principle as balanced audio signals, where the audio signal is split into two halves; negative and positive the BMU1500 mkII splits the 230v mains signal into two separate 115v supplies. One…

You must be logged in to leave a reply.