Ah yes, Class D. I am not a fan, but that’s only “so far”, because I don’t have any philosophical objections to it. Experience has taught me that it’s not what you do, it’s the way that you do it – and that’s pretty much what Bruno Putzeys thinks, too. You may not have heard of him, but he is the main mover and shaker behind the technology – insofar as it is applied to hi-fi at least – and if anyone should know, it is he.
Putzeys “served his apprenticeship” at Philips for ten years, where he was allowed to get on and do his own ‘skunkworks’ project. This became a class-leading Class D power module called Universal Class D (UcD) that Hypex ended up manufacturing. This family of devices was far more stable into varying loudspeaker loads than other such Class D designs; it has exceptionally low distortion, low noise and output impedance. Bruno duly joined Hypex and went on to develop the Ncore module, which takes this stability to an even higher degree, and has still lower distortion.
UcD has been out on the market for a while now, but the Ncore modules are only now making their way to consumer audio products and one of the first is Marantz’s fine sounding PM-10. Now the Mola-Mola Makua/Kaluga preamplifier/monoblock power amplifier combination you see here (£7,499, £9,998 per pair, at the time of launch) has surfaced with Ncore NC1200 chips inside, designed by the man who invented the technology himself. At the very least, expectations for this amp combination are high. If any Class D amplifier should be good, this is it!
Capable of producing a claimed 400W RMS per channel, the Kaluga monobloc is an exceptionally powerful product, making its five grand per box price tag look just that little bit more understandable. It is expertly out laid inside, meticulously put together with a custom amplifier board connected by direct-soldered star-quad cables. A large switched mode power supply is specified. The case itself is of an unusual design that swoops up and down from front to back like waves, alluding to the nautical name of both the company and the amplifier itself. The beautifully textured aluminium finish used throughout befits its high price point, although one wonders how resistant it will be to scratches later in life.
In a normal world, the Kaluga power amplifier would be the star of the show; a state-of-the-art implementation of surely the best Class D module on sale is no small beer. However, the partnering Makua preamplifier is also a stunner, and attempts to do a number of things that lesser designs either cannot. When you behold its rear panel and/or look inside it, suddenly the £7,500 price tag doesn’t seem so steep. Effectively it’s like a bay for various modules to be inserted, giving it all kinds of clever functionality. Above all there is a bold and original new user-interface, app-controlled via a smartphone or tablet to give enormous flexibility.
The five line inputs can be configured to be either balanced XLR or unbalanced RCA by a microswitch on the rear panel, and there’s also the option of a custom PWM DAC (£4,299) and a highly configurable MM/MC phono stage (£1,699) too. Each stage uses discrete amplifier modules working in single-ended driven differential mode, and run through a relay-based volume control which directly controls the gain of the output stage. There are also bi-amping outputs, balance and gain offset adjustment, and phase invert and mono modes – although you’ll need to download and install the app for anything more than volume control or source selection, which is done on the front panel.
The Makua has six ‘smart buttons’ which can be programmed for any combination of channel, processing and routing. This is done by the app – which generally worked faultlessly. Indeed it’s bi-directional so when you twist the fascia volume control, it tells the app which adjusts its own graphic display accordingly. When options are added – such as the phono stage – then suddenly the app offers up new functions, for example letting you select cartridge loading and gain. The overall effect is very convincing and not the sort of thing you’d expect from a new name in hi-fi with no provenance for this sort of thing before.
The Mola-Mola combo shows that it is possible to have a musical and tonally pleasant Class D listening experience. Indeed it’s so good that – fascinatingly – its lack of vices makes you realise just how impure Class AB amplifiers can sound. The Makua/Kaluga combo is open, detailed, balanced, even and largely devoid of character – in a good way. There’s no sense of it trying to editorialise, or being hamstrung and held back by its foibles. Whenever it is needed, there are huge swathes of power available, which are summoned up with amazing speed, yet there’s never any sense of strain. It makes playing the most demanding recordings look easy, with nothing in particular added or taken away.
This amplifier is able to scythe through even fairly dense and compressed mixes like this to eke out large amounts of low level detail, which it then strings together in a delightfully rhythmically coherent way. At the same time, its innate clarity gives real body to human voices, carrying their unique textures with real skill. On top of this, it’s able to swing vast amounts of power when the music’s dynamic peaks demand it, without failing in any of its other duties. If you think about it, that’s just what an amplifier should do – any amplifier, regardless of Class.
There’s still some sort of innate ‘Class D-ness’ to its sound, but not in a bad way. You’re never fooled into thinking you’re listening to a large, louche valve amplifier; it doesn’t have that divinely supple rhythmic feel. Instead everything is precisely ordered and perfectly slotted into place; there’s a kind of military precision to the way this combo carries rhythms. It’s actually very satisfying, because it has the firepower to make sure it works perfectly all the time, everytime. The Mola-Mola just gets on with the job of pumping out power, never phased and never floundering – even when driving really hard loads like my reference Yamaha NS1000Ms.
There’s much to admire in its tidy, ordered presentation – it breezes through dense rock productions like a hot knife through butter. The interesting thing is that although this amplifier is quite forensic, it never sounds clinical. It lacks the ‘matter of fact’ nature of many of its Class D brethren. Instead it focuses on setting up an exceptionally wide recorded acoustic, inside which instruments are located with riflebolt precision, yet are still allowed to breathe. If there’s a downside, it’s simply that it doesn’t quite have the swing of traditional Class A and AB amplifiers; the music seems just a that bit more orderly and tidy, and can’t seem to really break free. As such, it’s all down to personal taste – if its hugely powerful and controlled sound is what you crave, you’ll struggle to ever find better. Without doubt the finest Class D amplifier I have yet heard, the Mola-Mola Makua/Kaluga pre/power combo is also superb in the wider scheme of things.
Bruno Putzeys on Class D
“Most Class D modules sound poor because they’re industrialised well before every last stone is turned, and there the innovation stops. That’s how it works, until manufacturers see a competitor go screeching past, who then in turn goes to sit on their laurels. That’ll never work – if you want to have some hand in your own destiny you have to race yourself, not someone else!
I was born in Belgium, and I grew up loving audio and was fascinated by valve amplifiers. I then went to work for Philips in Leuven, who gave me the opportunity to try out every crazy Class D idea I wanted to. There I came up with Universal Class D (UcD), and then moved to Hypex to commercialise the technology and invent the follow-up, Ncore. Mola-Mola was set up to implement this in my very own way; the name is stylish, wacky and impossible to forget!
Class D is the obvious choice for all the right environmental and practical reasons – low power consumption, low heat generation, high efficiency, etc. – but it has been a fantastic challenge to get good audio performance from it. This makes learning how to design audiophile Class D amplifiers a worthwhile investment.
I am a co-founder of Kii Audio, and working on active loudspeakers. In parallel I started research company Purifi with Lars Risbo (of TacT Millennium fame) where we threw ourselves at loudspeaker drivers. Mola-Mola is now working on a standalone version of the Makua DAC module, which does to other DACs what the Kalugas do to other Class D power amplifiers! And after that you can expect a very special integrated amplifier…”