Here is our in depth review of a Class D power amplifier from Nord Acoustics: the Nord One UP NC500.
Nord Acoustics – a bit of history
Nord power amplifiers are hot property right now, you know that if you are reading this. Nord Acoustics is owned and run by a nice chap called Colin from a purpose built shed in his back garden. In a relatively short space of time he has built up an international customer base and earned rave reviews for his hi-fi products. This power amplifier is the reason why…
Colin originally setup a company called iQ Speakers providing a DIY (do it yourself) speaker building service, specialising in speakers from IPL Acoustics. I own a pair of these, the S2TLKs – fab speakers they are too. The IPLs are intended for the DIY market, which means you buy the speaker parts as a kit and assemble it yourself at home. However, many people (myself included) have no skills or tools to do the job. Colin provides these skills, at a modest cost, allowing everybody to get access to these fabulous speakers.
Naturally, Colin looked to go further than simply providing great value for money speakers. iQ went on to became the sole UK distributor for Abrahamsen amplifiers and CD players. Abrahamsen are owned and run by Per Abrahamsen, one of original engineers for Electrocompaniet. The Abrahamsen products again are excellent value for money, combining excellent engineering with value for money.
Colin then began to experiment with amplifiers based on Hypex nCore modules. The Hypex nCore modules are Class-D amplification and have been causing a storm over the last few years. The nCores promise to shake off the bad reputation that Class-D amplifiers have in some parts. Variations of the nCore module (the NC400) are used by NAD, Acoustic Imagery, Bel Canto, Mola-Mola to name a few. Those brand names are charging several thousand dollars / pounds / euros too.
Nord Acoustics – today
So here comes Nord Acoustics with their take on the Hypex nCore amplifier. This time the NC500 variation is used – as with the the IPL speakers, this was intended for the DIY market. The NC500 is essentially the same as the NC400 in terms of performance but is more customisable which is what allows Nord to do their magic.
Again, what Colin provides here is an assembly service for those who are less technically minded (once more, like me). You are effectively paying for the parts and for someone to assemble them – just like anything else I suppose.
Nord provide a few variants on the Hypex NC500. First there are the Nord One NC500 stereo and mono-block amplifiers which both come in standard and “UP” varieties. The “UP” is a term borrowed from Abrahamsen and it refers to the inclusion of Nords’ own input buffer board – this is the magic part, more on that later. Each of the above is also available as an “SE” version – the technology is the same but it comes in a fancier Japanese-built case for a small extra fee.
Also available are smaller amplifiers based on Hypex NC250MP and NC500MP modules, which provide a cheaper, smaller form factor. Intended usage for these are within DIY active speakers and multi-channel setups. Completing the line up is the Nord One Pre-Amplifier.
Unboxing the Nord One UP NC500
My review today focuses on the Nord One UP NC500 Stereo Power Amplifier. This review effectively also covers the mono-block versions as they are pretty much identical. The Nord One UP stereo power amplifier is dual mono and so contains the same innards as two mono-blocks. The only difference is the extra case and power supply. This is a truly balanced power amplifier, if you look inside there is two of everything – this is a good sign.
Upon opening the box, it becomes plainly obvious that the Nord power amplifier is a DIY job. The finish is basic and the case resonant. The edge of the aluminium facia and black body are sharp to the touch and a little uneven in places. The Nord logo is a soft touch sticker applied to the front. It doesn’t give the impression of quality when viewed from close up. Admittedly this is hardly noticeable when it is sitting in my media cabinet and I am viewing it from my sitting position.
The Nord One power amplifier is smaller than most other HiFi components as it is approximately two thirds width. No big deal.
Hooking it up is easy. The Nord One UP only accepts balanced XLR cables, so make sure you have the right cables beforehand. If your preamplifier is not balanced then you will need unbalanced-to-balanced converter cables – Nord can sell some to you for about £45. The speaker terminals are fairly chunky and feel like good quality. There is a master power switch on the rear, plus a power switch on the front complete with bright blue LED.
Listening to the Nord One UP
My initial concerns of how it looked evaporated once I heard it. Fresh out of the box, with no run in and little time to warm up, the Nord had already made a good impression. This baby packs a lot of punch! The Nord will output 400W into 8 ohms and 700W into 4 ohms, so you should have no worries over whether it will drive your speakers.
Class D amplifiers are like marmite – you either love them or you hate them. Lovers will talk about power, energy efficiency, bass response, heat and size. Haters will talk about a lack of emotion, how Class D sounds cold, harsh or brittle. I can say for sure that this is the best Class D amplifier I have ever heard. I believe the aim of Hypex to make Class D more acceptable has been a success.
The bass response is epic – very deep and extended but without “bass bloom”. Mid range and treble performance is even handed. I never felt any part of the frequency spectrum was too loud or too quiet. The Nord One UP doesn’t impart much character onto the music at all – you feel that it is doing a grand job of just telling you how it is. There is bags of detail in the music but it is not bright and doesn’t force detail down your throat. It is refreshing to hear an amplifier give you detail without stuffing it down your throat.
Interestingly the Nord One does run warm to the touch – this is because the case itself acts a heatsink and this is perfectly normal.
Earlier I mentioned that Nord’s take on the Hypex nCores was to include an input buffer board. The Nord input buffer board is now in it’s third iteration (revision C) with the previous two designs being discarded due to poor measurements and a more artificial sound. This board is what makes the Nords special when compared to any other Hypex nCore amplifier (including some of the branded amps). The Nord input buffer board allows different “opamps” to be placed which can have the affect of changing the character of sound produced by the amplifier.
In this way you can swap the opamp for other opamps, a process called “Opamp Rolling”. Users of vacuum tube amplifiers will know all about “tube rolling” – this is similar.
Nord will sell you opamps from Burson, Sonic Imagery and Sparkos. I tried both the Sonic Imagery 994 and Sparkos SS3602. You may read elsewhere that opamps completely change the characteristics of the Nord – this is not true. There is a difference but it is quite subtle.
The Sonic Imagery 994 give slightly better detail retrieval, slightly brighter feel to the music. The Sparkos SS3602 give a slightly warmer feel. My favourite was the Sparkos as I felt the SI994 left me feeling a bit “cold” about the music – it was impressive in an analytical sort of way but lacked “soul”. Your mileage may vary as a lot will also depend on your source (CD / streamer / vinyl), your speakers, your music and of course – your personal taste. The differences were slight and not as significant as swapping one amplifier for another one entirely.
Nevertheless, the ability to change opamps is unique in itself, I don’t know of anyone else that provides this outside of the DIY market. We all like music to sound in a particular way, the Nord One UP NC500 gives you that unique ability to customise the sound.
In the picture above you can see the Nord One UP NC500 sitting alongside the matching Nord One Pre-A preamplifier. These are flanked by the IPL S2TLK speakers, also built by Nord / iQ.
I thoroughly enjoyed my time with the Nord One. It punches well above its weight sonically and will get the absolute best out of your speakers whatever they may be. The neutral nature of the Nord means it will be easy to match with the rest of the your Hi-Fi system. Looks wise it isn’t great, but you an always try the new SE version or hide it inside a cupboard or behind a cabinet door.
I can heartily recommend this amplifier without reservation – it makes its competitors look over-priced and over-hyped. Nord have a rapidly expanding customer base who have used their amplifiers to displace much more expensive bigger brands. Highly recommended.