Maximum HeadroomGiven how much I liked the NuPrime-X MCX-2 stereo power amplifier, both initially and with some time to consider it in a broader context, how do the even more powerful mono versions rank? From the moment they were plugged these in, we’ve revelled in what these NuPrime’s can do. Let’s do a quick re-cap on the Nuprime X range – NuPrime originally targeted the new MCX series at the home cinema and gaming market. And I have no doubt that anyone looking to use any of the models will be blown away – they are that good. We’ve looked at them more in the context of systems that are primarily set up to play music and since reviewing the MCX-2 stereo power amplifier, I’ve been looking forward to the MCX-1s. But even with the foreknowledge of both the stereo model and a number of other power amplifiers that have both stereo and mono versions, I’ve been stunned by what I’m hearing. The NuPrime X MCX-2 stereo power amplifier is impressive but these babies are something else again. The identifiable character of the MCX-2, which I’ve described as a ‘live’ sound is present and correct yet the MCX-1 is unarguably better, as much in terms of quality as much as quantity. Despite the massive power rating, this is an amplifier of considerable subtlety and refinement. But perhaps we shouldn’t use the phase ‘despite the massive power rating’ because I’m starting to think that the power might be the key… The MCX-1 is all about the concept of headroom – this is having more power than you need so you don’t have this as a limiting factor. Which makes the MCX-1 the perfect amplifier those with large speakers and who really want to push things along. I can certainly see the appeal of this – when I was younger, all I wanted in an audio system was to replicate the impact of live performance. Even now I’ve just shifted things a little to cater for bands such as Alien Weaponry and we’re able to go past the live performance in a crowded pub to something like the band actually letting loose in your own living room. There is that much power on tap. Going loud is one thing, sounding great while doing it is another. And this is where NuPrime have it over everyone else. Because I’ve already explored the sound of the MCX-2 I’m going to first talk with you about the differences between the two models – Even from new, it’s obvious that the MCX-1 is more sophisticated — there is enhanced detail and precision and while you might not expect this, the sound is lighter, more articulate and open. The MCX-1 is considerably more transparent and better able to resolve fine detail. Like the MCX-2, the overall sound is warm but this is now tempered with a more open presentation and easier flow. It’s more relaxed and even more listenable (which is high praise given how much I like the MCX-2) The high gain and sensitivity means any DAC or preamp has an extremely easy load hence sounds more relaxed and fluid. So we find we are listening at what appears to be lower sound levels but what we hear is more dynamic – ie the difference between quiet and loud sections is made more obvious. But the fine detail in quiet sections is almost un-nerving. This has always been part of the Nuprime promise – a dark deep soundstage with even the most nuanced sounds appearing with a level of clarity we have not previously experienced. On paper there should be no difference with noise floor performance between the MCX models but I’m absolutely convinced the combination of mono configuration and better internal isolation make the MCX-1s by far the best in the range.
Inside the MCX-1
Why mono?If NuPrime have the MCX-2 stereo amp why didn’t they just make a bigger version? By physically separating the left and right hand channels you gain much better electrical and RF isolation. And with two separate power supplies we make further gains by eliminating interaction and resonance as well as exactly doubling the available power. The MCX power amplifiers are effectively modular – the 4 models all look the same from the front and have what appears to be the same power supply but have a choice of 1,2,3 or 4 channels of output. The 3 multichannel models all have two amplifier boards inside but the MCX-1 only has the single module. This answered the obvious technical question, being was the MCX-1 just a bridged version of the MCX-2? It isn’t. With just the one amplifier module, MCX-1 has the greatest amount of free space inside and the 3 boards – power supply, capacitor bank and amplifier board are well separated. I think this also contributes significantly to the sound quality we hear. Then there are the simple economies of scale – the MCX series are effectively all reconfigured versions of the same design so the more you build in the same casework, the lower the unit cost. And really, the two MCX-1s are still more compact, lighter, cooler running and more affordable than many 100 watt stereo amplifiers.
SMPS – the Switch Mode Power Supply.Most audio amplifiers employ a conventional transformer, often toroidal (donut shaped) for their power supply – these are not without issue being costly (much copper wire), limited in output and prone to creating interference from their strong EM fields. And they run at mains frequency – that’s 50 hertz so you often get a very particular hum, even more so with powerful units – this can be either audible from the amplifier itself or through your speakers. The MCX range use a switched mode power supply which takes the incoming AC but kicks the frequency up far beyond 50 hertz. The trick is that the higher the frequency used, the smaller the transformer can become. Likewise when making the conversion from AC to DC the parts can be much smaller and higher in tolerance and specification. So when you look at the power supply section, if you can even recognise the transformers, they are tiny. So the primary benefit of the SMPS is speed – by operating at a much higher frequency than the mains power supply it can respond to the music’s demands. NuPrime aren’t the first people to use switched mode power supplies and for may of their earlier designs used off the shelf units.What sets the NuPrime MCX power amps apart is that they have produced a dedicated SMPS – it’s a complex board but you can see it in the internal pictures. Again, this appears to be derived from the original MCH-K38 and what previously pushed 8 channels is now fully allocated to just one in the MCX-1. I want to also re-iterate that both the amplifier modules and power supply sections are all Nuprime’s own work – most class D amplifiers employ some variant of the Hypex or ICE amplifier modules and either an off the shelf torrid or SMPS. So while these ones don’t have to re-invent the wheel, they are limited to what someone else’s technology can do; the slower switching speeds – 300kHz are an obvious limitation. The MCX-1s switch at 550kHz The almost direct relationship between power supply and output of the MCX amplifier really is the key to their performance – only an SMPS has both the speed and power to keep up with the demands of the amplifier section with the capacitor bank providing a degree of isolation and storage.
How do the MCX-1s compare with NuPrime’s other Mono amplifiers?The obvious question is how do the Evolution Ones improve upon the MCX-1s. The appreciably higher switching speed of the Evolutions (750kHz vs 550) do give them a real advantage in terms of speed, absolute resolution, noise performance and transparency. The much more costly build, use of premium parts and linear power supply, not to mention the 1000kOhm input impedance all contribute further. Yet with the much higher rated output, the MCX’s can open the sound out and deliver a warmer character with subterranean bass that will make them a better choice in some systems regardless of cost. I’ll also point out that if any of this significant saving is diverted into better source components the balance can shift even further in the MCX-1’s favour. So you do have to look at the choice in the context of a complete system. The choice between the MCX-1s and NuPrimes similarly priced ST10Ms is rather more pragmatic – smaller speakers, especially if used in near field or smaller rooms will just be overwhelmed by both the power and high gain and depending on the characteristics of the source. In this setting the ST-10Ms are more appropriate and accurate. But if you have the room and larger speakers, I’d be heading straight to the MCX-1s.
Conclusion.The NuPrime X MCX-1 mono power amplifiers offer an unmatched mix of both power and quality at a surprisingly affordable price. While the 750 watt per channel rating may at first appear daunting, it allows an ease of delivery combined rich warm bass that makes for enjoyable listening at any level. Best matched with larger speakers to fully explore their potential, the MCX-1s are a star product in NuPrimes ever expanding portfolio of high end electronics.
Nuprime X MCX-1 750 watt per channel mono amplifiers NZ$3900 each including GST and delivery.
Client feedback…One of our clients has penned a great summation of the MCX-1s below – just too give you a bit of context they have the large floor-standing Monitor Audio Gold 300s and have been using a Nuprime DAC10/ST10 combination with them – the MCX-1s replace the ST10 and while there as still some things that the ST10 does very well, the extra extension, headroom and control of the MCX-1s win out.
You’re not getting them back! The ST10 is boxed up and sitting in my car. I’ll drop it off after work tonight if that is OK.
I think that your review was very much on the money. A substantial meaty sound but still with agility (see I can talk stereo speak). But seriously a really nice bottom (think Sophia Loren (Sorry I couldn’t resist that) and well balanced mids with dynamic punch. The mid to highs are still well defined, clear and spatially wide/deep.
So far so good and this is where the comparisons come in, bearing in mind that I have only the AudioAnalogue (Maestro) and the St10 to compare it to. The audio analogue is a different kettle of fish, much loved and used every day but not in this league for strength and depth (you are not getting it back though).
The ST10 does some things better than the MXC though. Better sound stage, I mean clearer, the separation of instrument is more defined, the top end almost bell like, crystal, whilst the mid and bottom are superbly dynamic and, where present the bass is quite rewarding. So different beasts I think, one monster and one angel. But, and I know that you are onto this in spades, it’s about match, the MA300’s are big and boy do they respond to the more muscly inputs of the MXC. There is some sacrifice of that very fine detail at the top but the ribbon tweeters are so blinkin sharp that criticism is pretty much negated anyway. The system is warmer, bigger, meatier and ultimately, for me, a lot more rewarding and genuinely impressive.
I could waffle on with hyperbole for hours but would just end up repeating myself. In essence the ST10 is just a wonderful amp but probably not so suitable to drive the MA300’s as well as the MXC1 does.
I also think that the MA’s are starting to break in again now they are operating in an area they haven’t before. (Oh alright, don’t laugh)
If anything the total sum of the parts is more real whereas the ST10 is leaning to the hyper-real.
Two other points though – Jenni immediately picked up the difference and likes them (and I wasn’t even playing John Grant). I spent the weekend being pummelled into submission listening to a very expensive top end system built around ATC100’s and every conceivable bell and whistle imaginable. It is impressive and really does sound great. Well balanced, huge but responsive and here’s the rub, the system that you have built up for me is really, really close to that, if not already there, in two easy steps. Hooray.
I’ll give it a rest for a while and start tidying up the cables next, but in the meantime I’m really looking forward to playing all that music and finding that extra previously hidden depth that will now be liberated. (I bet that even Dire Straits sounds good on it)