Hardware Reviews

Nord Acoustics Three SE 1ET400A MKII


The name of this amplifier tells you that there has been quite a bit of evolution in the Nord Acoustics range, something that a brief look at the website backs up, Colin North has been making class D amplifiers for some time now and the sheer variety of options on offer is quite an eye opener. But once you get to grips with the fundamentals it becomes things become more clear and you realise that there is a lot more potential for finding a perfect fit amplifier for a given budget than is the case with the majority of brands. For those who are interested in the building blocks of modern class D amps Nord offers an unusually comprehensive range.

Most of the Nord power amps are based around Hypex N Core modules, which are arguably the most successful output stages in serious class D amplifiers today, they offer high wattage and are renowned for a clean, fast sound that is far removed from earlier class D designs. Amplifier guru Bruno Putzeys was heavily involved in the design of the N Core module and now he’s making the most of their reputation by building his own version called Purifi, and it’s the Purifi module that differentiates the Nord Three amplifiers from its other models.


Internal view with Sonic Labs op-amps top centre

To start at the beginning, the Three SE 1ET400A MKII is a dual mono, stereo power amplifier with two Purifi 1ET400A output devices producing 227W per channel (the 400 refers to output into four Ohms). These are backed by a pair of Hypex SMPS1200A400 switched mode power supplies and the amplifier has Nord’s Rev D buffer boards with which you get the choice of Sparkos or Sonic Imagery discrete op-amps. The latter add £45 to the price while replacing the Neotech copper internal cable with a silver plated copper alternative doesn’t change the cost. The only other option is whether to include a 12v trigger which adds £50, this being a popular feature in the US but not something the Brits tend to use. Note that all Nord’s prices are plus VAT except the one at the bottom of this review which is the full UK/EU price.

It’s very unusual to be able to choose components within an amplifier but given that Nord sells direct it’s not possible to hear the difference between them before ordering. There is plenty of information on the site to help with the decision however, the Sparkos SS2590 op-amp being described as having “a rich and warm detailed Class A sound… If your speakers are forward, bright choose the Sparkos”. While the Sonic Imagery 990Enh “is slightly more open and accurate than the Sparkos… And still has a warm and accurate Class A sound [it] was our favourite but I just bought JBL 4367 speakers for the dem room which are quite forward, I now prefer the Sparkos, but its close both are superb”. If you want to try both it’s possible to ‘roll’ op-amps, that is swap different models in a bit like the way some folk roll tubes/valves.


Nord also take voltage regulation very seriously, Colin says the discrete regulators in this amplifier cost him $200 per channel, which makes the final asking price look very reasonable indeed. This is largely because they are sold direct and don’t attract mark ups from distributors and retailers that usually mean using $400 components would add at least $4,000 to the retail price. So in value for money terms these amps are very strong indeed. The SE casework is off the shelf but Japanese made and high quality, you get thicker metalwork on amps with high end prices but that does not translate to better sound quality. The Nord amps have high quality components throughout, just no fancy machining on the box. The cable terminals are substantial and the XLR inputs equally professional in standard, you can get RCAs as well for a £75 premium. Another unusual option is that Nord power amps can be had in one or two chassis, but both stereo and mono versions contain the same components, so effectively you pay for the extra box and build work which that involves. It seems counterintuitive but if you want to put an amplifier next to each speaker it’s nice to have the option.

Sound quality
“Fast and bulbous” were Captain Beefheart’s words, fast and clean is the most succinct way I can describe this amplifier. It really does seem to be fat free when it comes to the ability to move as fast as the music signal requires, there is no apparent overhang which makes the bass as nimble as the mid and treble, even with relatively difficult loudspeakers. I used Bowers & Wilkins 802 D3 and PMC Fact.12 Signature speakers and in both instances it had no trouble getting them to jump when it said so, more impressive really is that they stopped jumping just as quickly. It’s not as difficult to set something in motion as it is to stop it without any blurring or distortion but this Nord does that remarkably well. It’s delivery seems to be devoid of the distortions associated with class AB amplifiers, which is most amplifiers, and these tend to sound a bit sluggish and thick by comparison. They have redeeming qualities of course and they are equally enjoyable but this class D design does most things extremely well for its price.

It’s so clean that you end up playing louder than usual and enjoying the huge vistas that certain recordings throw up, Leifur James’ ‘Red sea’ (A Louder Silence) does this with its seascape background, there is even what sounds like creaking rigging back there and some real juice on the bass guitar. The Nord produces a lighter, brighter balance than I get with an ATC P2 power amp, one that opens up vocals and illuminates the sublime when it’s on the record. Tord Gustavsen’s The Other Side album contains quite a lot of this and sounds immaculate in the Nord’s gentle grip, with plenty of ‘air’ around the cymbals and every nuance of the piano made clear. It really made the most of the speed and resolution produced by Rega’s P10/Aphelion 2 record player, that and the hall defining scale of the fabulous Espana recording by Chasing the Dragon.


I tried this amp with the Node Hylixa speakers reviewed earlier in the year and was impressed by the way it brought out their dynamic capabilities, these are not terribly sensitive loudspeakers and they need a bit of driving, something the Nord proved more than capable of doing. The combination making Captain Beefheart’s Clear Spot album sound fabulous, especially the guitar on ‘Nowadays a woman’s gotta hit a man’ and pretty much everything on ‘Circumstances’ which is the standout from that career highlight of an album.

With the fact.12 Signature the Nord delivered nice weight in the bass and produced a highly engaging result that brought out the fabulous vocal recording on Stephen Malkmus’ recent release Traditional Techniques, which hangs together superbly through this amp/speaker pairing. The Grateful Dead’s live Reckoning album was also very good thanks to holographic imaging and substantial bass extension behind the touching harmonies of ‘China doll’. Gil Scott-Heron’s ‘The revolution will not be televised’ also made an impression, primarily that this amp is as fast as quicksilver, the razor edged lyrics were as clear as day even if the recording is a little short on bass. I mentioned a desire for more bass to Colin at Nord, assuming that the problem lay with my relatively bass light room but he said that those looking for the full effect at low frequencies should consider the One SE NC1200, a more powerful Hypex powered amplifier that comes in at £750 more than this model; as you can imagine I’d like to hear it.

Put on a really well balanced album like Steely Dan’s Gaucho and there’s some real meat on the bass, and impact to the kick drums, this amp is not bass light in any respect it’s just devoid of the thickener that you get with most class AB designs. This is also a factor of the speed, the slower bass is the heavier it seems regardless of whether this is accurate or not. With anything but live acoustic music it’s very hard to know how much energy there should be in the bass, in fact if you tend to listen to mostly acoustic material this amplifier is more than likely to be right up your ally so to speak. Back with the B&W 802 I put on Rickie Lee Jones’ Flying Cowboys, one of best later works, and enjoyed the taut, immediate sound of this excellent recording. This amp is transparent enough to dissect pretty much anything but doesn’t lose sight of the groove, nor the weight of a big kick drum when one comes along. The all analogue vibe of Bill Withers’ ‘Sweet Wanomie’ contributes to the heavy if somewhat woolly sound of the bass and helps to make his debut album super mellow and smooth without being saccharin.


The Allegri Reference preamp came in whilst the Nord was in the system and opened things up quite considerably, the extra transparency and effortlessness of this component meant I could play intense stuff like Zappa’s ‘Wind up working in a gas station’ (Zoot Allures) at higher levels, it also revealed all the layers of the recording. The live cut of ‘Black napkins’ on that album was blistering with this combo, reiterating the fact that Zappa was a highly underrated guitar player. I also stuck on Little Feat’s Time Loves A Hero which sounded perfect from the off, with lots of punch and excellent timing on ‘Old folks boogie’.

Listening carried on long and late enough to say that this Purifi based Nord is a tremendous amplifier for the money, I’m pretty sure you can’t get this level of power, speed and transparency for the same money anywhere else. The fact that you can’t try before you buy is essentially the price you pay for this degree of value for money, if you look at competing products that use the same technology prices are at least two or three times higher, which is what it costs to get audio components into a retail environment. Class D does have a distinctly different character to the class AB amps most of us are used to but when it’s done well those characteristics have a lot going for them and this Nord amps is certainly done well.


Type: Class D Purifi based stereo power amplifier
Analogue input: XLR socket
Analogue outputs: CHK binding posts
Power output: 227W/8 Ohms, 450W/4 Ohms, 450W/2 Ohms
Frequency response: 20 – 20kHz +/-.01dB
Sensitivity: Gain 26.8dB, 2.23V RMS for full power output
Distortion: THD+N 100W – 0.001 % 20-20kHzHz
Signal to Noise Ratio: 131dB
Dimensions (HxWxD): 85 x 428 x 330mm
Weight: 6kg
Warranty: 2 years

Price when tested:
Manufacturer Details:

Nord Acoustics
T +44 (0) 1242 650559


stereo power amplifier


Jason Kennedy

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