NVA Balanced Mains Unit BMU 1KVA


Normal mains is single ended. By changing this to balanced you remove noise and distortion. UK mains quality can be very poor. There's a strong possibility that you won't hear your system at it's full potential until you try our BMU. The BMU plugs in the mains wall socket and acts as a distribution box to four separate sockets mounted on the top of the unit; these can be used in the same way as any mains socket.

The NVA BMU can feed a larger system, subject to power requirements, by running an extension block from one of the BMU sockets - please check with us before ordering. 

  • Bespoke all-acrylic case
  • Audio quality unswitched sockets
  • 1KVA audio-grade balanced transformer
  • Soft-start fitted as standard
  • Thermal cut out to prevent accidental overload
  • Dimensions - w350mm x h140mm x d290mm
  • BMU instructions
Choose Mains Plug Type:

Paul kindly delivered my new NVA BMU unit yesterday, and I spent the latter part of the afternoon re-arranging equipment and socketry to suit the new arrival. This 'review' is based on listening to one vinyl album and three CDs, so it is only a snapshot view, but there is a noticeable uplift in sound quality. Apologies for any hifi w*nk words that follow...The first thing I noticed I'd call 'presence': the soundstage seems to have moved forward and is sharply defined. Bass quality has improved immeasurably, being less 'woolly'. Albums I know well seem to have been 'turbo charged': they feel 'faster', & previously hidden details brought into focus. It feels far more dynamic. I'm normally not one to make early comment, wanting to live with a new piece of equipment for some time before commenting, but this was a real surprise for me. I had assumed that my mains supply was good enough (between 236 and 244V, no extraneous noises), but it certainly benefits from the BMU. It's still early days, but all I want to do is get back home and play some music.

The BMU just arrived, I've already unboxed it and set it up and everything is running great! The info from the DAC on the input voltage suggests that we shouldn't have any more problems. Thanks so much for your work in sorting this. The BMU has really transformed things. I've undertaken various tweaks and upgrades of my core system over the past several years, and nothing has had such an obviously improving effect as the installation of the BMU. The most easily discernible effects were that the soundstage is now markedly wider - the sound now seems to be coming from well beyond the boundaries of the speakers - and that the bass has deepened and become more prominent, balancing out what was a disproportionately prominent midrange (which I'd previously assumed was just the character of my speakers). This is very obvious when listening to jazz LPs - the double bass, with it's place and contribution in the ensemble, is now much easier to discern, making performances that I'm already very familiar with sound fresh and exciting. Finally, the sound now seems to occupy more of the space in between me and the speakers, filling out more of the room, rather than just being at the speakers. I wouldn't be surprised if there we more subtle changes that I've not picked up on yet, but these were the most obvious ones. Needless to say, I'm delighted with the purchase and there's no question I am keeping the BMU.

Balanced Mains Unit. The idea is logical - normal AC runs in a sine-wave from 0 volts to 240 volts, 50 times a second. The BMU has a transformer that alters the voltage from +120V to -120V. Still having the 240V difference to power equipment but the plus and minus voltage is now 'balanced', in harmony, equal, whatever. It is a mysterious black box. A single mains lead out and four mains sockets on the top, somehow bigger - and more imposing - than expected. The effect is silence. Not just any silence but an empty silent void waiting to be filled. Sounds come, music, instruments, effects. I firstly went through a selection of tracks just to get an idea of what was going on. It's the room that everything gets. And this is most noticeable on acoustic instruments. I put on Michael Hedges 'Aerial Boundaries' and instead of being blown away I was sucked inside. There is a liquid serenity that just holds you gently in the music and you simply don't want to leave. It took me three tracks to realise that the one I had wanted to hear had long finished. Then onto Rachel Podger's magnificent recording of Biber's 'Rosary Sonatas'. Not just am I hearing far more in the sense of nuance and inflection. The whole recording is a natural, living entity that you can literally walk into. Some equipment doesn't like the BMU - specifically a Schiit headphone amp. But for the rest running CD players, DAC's Pi streamers and amplifiers - they all sound so much more refined and in control.

Thought I'd send you a photo of the NVA BMU unit purchased from you. It has rejuvenated my old Quad 909 and Artera Play and fitted into my Quad racking system perfectly. A significant improvement in sound quality for a modest outlay. All my old CD's have come out and am hearing things not heard before. Thanks for the fast delivery. I look forward to many years of use.

The BMU arrived about 10 days ago and, unusually, Doc gave the opinion that it would need about a week to run in. Uncannily accurate. It seems to have just come on song and I might aspire to greater improvement with time? It is neat and heavy with a long lead. I prefer the black sockets provided to the gold ones shown on the e-bay illustration - but let's face it, who is going to see the sockets? I parked mine behind the rack (no comments please) where it sits and buzzes gently at about 100Hz (I assume). I simply love what it does and I trust it will also solve my "bad mains" afternoons (none so far). You can read the effects in the other reviews in this thread and they are all true. Another recommended product.

NVA sells, and ships, direct to users. This saves you around 40% compared to buying through a dealer. We are so confident in the quality of our products and designs that we offer a 30 day no quibble returns policy. Listen to NVA in your own system, in your own room (by far the best way to judge any item) for up to 30 days. If you’re not delighted, return it to us for a refund.

How it Works

First, you purchase the item(s). Once your order is delivered, the 30 day trial begins. To return the item(s) within that 30-day period, contact us by email. We will provide you with a return authorisation number (RMA). You then return the item(s) to us by your choice of courier. Once we've received your return, you will receive a refund within 7 to 10 days.


The returned item(s) must be in the same condition that you received them in. If there are signs of user-related damage or missing accessories, then we may deduct a portion of the refund.

Shipping costs are not refundable.

For full details, please see our Returns Policy

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