NuPrime AMG PRA analogue preamplifier

In Part One of our review of the NuPrime AMG PRA analogue preamplifier we find that in performance gained for the end cost, this is one of the very best choices for analogue enthusiasts. NuPrime have dug deeply, with both lessons learned from previous designs and new innovative approaches to deliver a genuinely high end component that’s still broadly compatible and affordable.

There are both risks and rewards in doing things differently. Nuprime aren’t afraid to do this and the new little analogue preamplifier is a case in point – a resolutely analogue product launched into a digital world with an unusual mix of features and design points.

The NuPrime AMG PRA  might, at its heart be an analogue component, yet it weaves magic into digital replay and shows us that music is what matters regardless of how it is stored or delivered. So if Digital is your primary source skip to Part Two and you’ll learn how the PRA works with digital sources, how it compares to other options, and advice on matching with power amplifiers and cables.

The pre-release statements were nothing less than ambitious – ‘beyond transparent’ being the headline yet NuPrime offer the ability to actively manipulate sound with a form of bass control. The PRA is very simple with just 4 inputs and two outputs, manual front panel selections and includes almost over engineered remote.

So how does it live up to the promise and how will it improve your own system?

The logic behind separating the pre and power sections of amplifiers is well traversed – optimisation, isolation and flexibility. The NuPrime AMG PRA also makes a point of not including digital – but in Part Two we’ll look at how we bring this into the mix, as despite it being a little counterintuitive, the PRA has a lot to offer in systems with digital.

The NuPrime AMG PRA is almost a completely new design yet does draw upon previous NuPrime and NuForce models. While we can look to the similarly proportioned NuPrime HPA-9 and NuForce HAP100, there are also the high end models – such as the NuForce P-9 and P-20 which were produced from around 2005 to 2014 but never made it to New Zealand. Yet all were extremely well reviewed in high-end circles and were unique products in both design and execution.

The purpose of a preamplifier in systems is often misunderstood. While it offers utility in terms of input switching and volume control, there can be an assumption that, at best, it will just pass on the signal – hopefully without too much degradation, to a power amplifier and be close to audibly invisible. The proponents of passive preamps see this as ideal. By passive we mean it has no input power.

Yet anyone who has experienced a serious active preamplifier knows that there is much more to the story. They literally bring music to life and leave an indelible impression – I’ve never forgotten the first Audio Research I heard and it’s remained a bench mark to which everything else has aspired but never replicated.

The PRA exists in a far more affordable space, being physically much smaller and simpler. It relies on innovative design and some quite radical approaches which give a measure of endearing quirkiness. But above all else, it does things with sound that I’ve not heard before in any setting. As promised it is ‘beyond transparent’ because it’s not just passing a signal – it is dramatically improving it.

You may ask why we don’t just connect source components directly to power amplifiers – in part there is the lack of control of volume but most sources simply don’t have the electrical output to either correctly match or drive power amplifiers to their full potential – they will work after a fashion but there is a price to be paid in lacklustre dynamics and loss. A passive preamplifier can’t actually amplify – all it can do is attenuate.

An active preamplifier such as the PRA, not only takes signal but also power and is by definition an amplifier – you get more out than you put in. The question is – are these additions distortion or or untruths? The isolation from power supply noise and the effective processing of a signal in order to magnify it will inevitably have some audible product but on the other hand there can be huge benefits that, as we’ll show with the PRA, create a much more lucid, engaging and rewarding rendition of music within a system.

Nuprime AMG PRA rear
NuPrime AMG PRA rear panel connections.

‘System’ is the key concept here as the PRA can only work within one – it needs one or more sources and must be connected to a power amplifier, (or a pair of). It follows that there are 3 parts to the NuPrime PRA story – the inputs, the internal processes and the output. So let’s start at the start…

For many of us, vinyl records have always been at the heart of our listening preferences – and there is no reason not for them to happily co-exist with a digital collection. If anything, digital has driven progress in analogue by presenting a more accurate sound without the artefacts of surface noise and tracking issues. Accordingly our record playing systems are far better now than 10 or 20 years ago – in terms of both absolute performance and affordability.

The recent arrival of some quite exceptional analogue components – the upgraded Wax Engine turntable, Well Tempered Phono Stage and the better Nagaoka MP series cartridges have combined to give us a great range of options which both feed the NuPrime a rather nice signal but also are very much in the same ballpark in terms of affordability and hence appropriateness when first listening to the PRA.

And I have to say, this is very much the product I’ve been waiting for from NuPrime – while they have numerous DAC options and even more power amplifiers, the PRA fills an obvious gap in the range and has a surprising number of applications.

And like all the NuPrime components we’ve listened to, there is a definite warm up period from new – this stretches into weeks so while the initial impression was better than positive, it’s just pointing at what is to come.

From the outset you’ll find the sound velvety and smooth – yet there’s an immediacy and rush of detail that makes production differences huge – we jumped from Lorde’s Melodrama, to Alien Weaponry metal to Avantadale Bowling Club hiphop in the first listening session and each LP sounded both huge and completely distinct.

With a month of serious listening in a progression of systems, I’ve enjoyed every minute of the PRA. The tag line for Well Tempered Labs is ‘new music from your records’ and this is exactly what the NuPrime does in this setting. Every turntable and phono stage combination reveals previously unheard details that upset our established hierarchy of performance. Crazy as it might sound, when first listening to our entry level turntable with an affordable MM cartridge, I was hearing passages, vocals and instrument lines that I’d not heard before in any context. I was starting to think that there might have been something wrong with our best turntable system. This seemed to be the only rational explanation given the price disparity.

But as we stepped the system up, the qualities of the PRA became more obvious. Once you hear what you have been missing there is no going back.

Transparency is one thing but transmission is another. As we noted at the start transparency is almost a passive quality – you can see through something. And there is no doubt that by conventional standards the AMG PRA is transparent. But it does a lot more than that – it effectively illuminates, expands and magnifies giving a level of clarity I’ve never heard before at this level.

This is not a colouration or distortion – we are literally being taken closer to the music because the PRA takes the original signal and amplifies it. Think of it as the audio equivalent of a microscope or telescope – you are making fine detail more apparent or bringing a distant object closer and into focus, The volume level doesn’t actually matter – when it’s really quiet and turned down low (the volume control runs from 0 to 99) there is still remarkable detail and the sound remains open. In ordinary systems you drop the volume and the sound often just goes dead and flat. The Nuprime preserves the clarity and balance. Yet as we run up, everything expands.

I’m going to reference Quad here and it won’t be the last time – Peter Walker suggested that the volume control should be thought of as a focus control. The PRA doesn’t go out of focus but what it does do is allow you to hit a definite sweet spot for any recording where it just sounds right. And this will vary depending on source, genre, the actual quality of recording and the rest of the system.

Amplifying the signal is an essential for both phono stages and power amplifiers so there is no reason not to do likewise within a preamplifier.

Having a phono stage with easily switchable gain such as the Well Tempered shows just how beneficial this is – set it too low and the sound is dull and compressed, no matter how much power is applied later. And within the world of phono stages there is a consensus that the electrical matching between the source cartridge and the phono stage is important. So it follows that doing likewise between the phono stage and preamp is also worthwhile…

NuPrime place real importance on the 1M Ohm (that’s 1,000,000 Ohms), input impedance featured in the PRA-s 4 inputs. The only other component we know with this are the Evolution One power amplifiers and I’m likewise going to go out on a limb here and suggest that it’s at the heart of what the PRA does. To recap – this can be regarded as a measure of how benign the PRA appears to a source such as phono stage, DAC or other line source. How much of an influence does this specification have to the end sound?

Nearly all preamplifiers have an input impedance around 47K Ohm (although very few even bother to state it).  47,000 versus 1,000,000 – that’s more than 20X difference. Clearly something significant is going on here. Bill Firebaugh of Well Tempered Labs is another advocating that higher input impedance is beneficial.

I can see your eyes glazing over as this is getting technical and I personally am still struggling to understand – in the most simplistic sense I think it enables the PRA to extract far more from a source.

If you understand that a well designed phono stage takes an almost vanishingly small signal from a cartridge and brings it up to line level (1.5 – 2v), while at the same time performing a re-equalisation (the RIAA curve), as well as dealing with widely varying impedance requirements, you’ll certainly be starting to appreciate how the NuPrime PRA provides an extension of this process.

Nuprime AMG PRA inside
Inside the NuPrime AMG PRA.

The power supply is interesting. You can see it in the pic above,  The PRA features a new variation that’s labelled ‘NuPrime Power Engine’. I’ve not been told exactly what’s going on here but what I hear suggests that it’s very clean and fast. The PRA runs barely warm so it’s clearly not full Class A like the HPA-9 but I could be wrong given it’s not a headphone amp.

Analogue sound quality can be a many splendored thing – detail, sound staging, dynamics, timing and pace are just some of the descriptives used. The internal process of the PRA brings up all of these qualities – music literally comes to life – what you’ll hear is a far more lucid, vibrant, yet sublime and involving rendition. It’s one of the biggest differences I’ve heard within the NuPrime range.

The output power of the PRA is generous enough to easily run most power amplifiers to their maximum and the front gain switch is useful to fine tune this. The adjacent switch is for absolute phase – this deals with several issues – some power amplifiers invert phase so this gives a system correction. But there are cases where recordings are also phase inverted and switching is a whole lot easier than swopping speaker cables. In the past I’ve struggled to hear much of a difference and would still regard it as subtle but with the PRA, the enhanced clarity does make it more obvious and so the inclusion is worthwhile.

The control knob on the right hand side deals with both volume and source selection – just press to turn on and cycle through the 4 inputs. The remote control is almost a component in its own right being finished to the same high standard as the front of the PRA, and of all metal construction – it is simple in layout and operation and works exactly as you’d expect.

On the left hand side the knob that on other NuPrime products controls source selection is actually a selectable 4 stage ‘Active Low Frequency and Harmonic Gain’. This is where things get interesting.

Anyone familiar with Quad will recognise this as a variation of the ‘Tilt’ control that almost all Quad preamps have featured for the better part of 50 years. It was originally introduced to help re-balance sound in compensation for varied recordings, sources, room and speaker response. While this runs counter to the purist philosophy of not altering the signal or frequency response at all, for those of us who live in the real world it’s actually very useful and worthwhile.

NuPrime suggest it’s primarily intended to compensate for the limited bass response of smaller speakers but I’ve found there’s more to it. Unlike a conventional ‘loudness button’ this isn’t a boy racer approach to bass – each step is reasonably subtle and even with floorstanding speakers you may well apply one or two steps for normal listening to give a warmer and more involving sound – especially with brighter sounding rooms or electronics. The sound also remains consistent as you increase volume so it doesn’t sound like it’s loading up the bass in an artificial way.

It absolutely does make smaller speakers sound better and bigger, but retains control and speed. My favourite Monitor Audio Studios sounded the best ever with a combination of the new PRA and the NuPrime MCX-2. The suggestion is that the bass adjustment gives a more natural sounding roll off and I’d agree – it’s far more subtle than a subwoofer and has none of the issues of integration or matching.

Yet with the floor standing Sonus faber Sonetto III just moving up one step also fleshed the sound out in a way that made me think that I was listening to the next model up – there isn’t a hint of added colouration. Purists will still want to use the PRA in its flat response mode but I’m finding the feature is adding to my enjoyment of music with no downside.

Does the PRA have a sonic signature? I’m still working to characterise this: when running the ‘flat’ setting control of the bass, speed and agility is remarkable and even initially overwhelming – yet there is no hardness. If anything there’s a softness to the top end which is quite liquid but I can’t quite work out if it’s the absence of distortion or a slight roll off relative to other amplifiers I’ve listened to.

While the PRA’s magnifying qualities do bring out the best in amplifiers and speakers, the PRA also shows up the differences in recording quality. On well produced vinyl – especially newer pressings, I’m in awe of the extra detail, the perceived reduction in surface noise and general analogue goodness. But some older recordings, while better than I remember, just don’t have the same impact. The PRA won’t magically juice up a flat sounding recording – it’s presented essentially as it is and while you can enhance the bass a little, the differences in production values have become a lot more obvious.

On the connection front the PRA has 4 inputs – one balanced and three RCAs. And a set of both balanced and RCA outputs. Balanced can be especially useful in reducing noise, especially with longer cable runs and there is a suggestion that the differences between cables are reduced in this format so it’s worth investigating further.

In the context of an all analogue system, the NuPrime AMG PRA is a magnificent little performer. I’ve moved between several turntable, cartridge and phono stage combinations and in every case, the PRA allowed me to hear much more than I had previously. We can quantify this – a system with the PRA and our entry level turntable fitted with a modest MM cartridge produced sound quality and detail that to my ears was better than that from the same system with a far better turntable and more costly MC cartridge but running via a competent DAC/preamp with line inputs.

NuPrime AMG & WTLs
Serious about analogue – Well Tempered Labs Phono Stage, the NuPrime PRA and WTL Versalex.

So in terms of performance gained for the end cost, the PRA is one of the very best choices for analogue enthusiasts. It will vastly increase your enjoyment of vinyl records. All the qualities you value in analogue will be enhanced and new music revealed, while offering a significant reduction in replay associated noise. The cost of the PRA is very much in the same ballpark as any other upgrade – be it turntable, cartridge, phono stage or cables yet the quantum of improvement is greater than anything we’ve heard with these other options.

It’s also worth understanding that the PRA will magnify any improvement you make to your system – a simple cartridge change for instance, will yield a result that’s far more obvious than it would have been with any other preamplifier.

Where does the PRA sit when compared to other preamplifiers? In many ways the NuPrime AMG PRA is out on its own – how many new analogue preamps do you know of? And given it must be run into a power amplifier, chances are that most PRA’s will go into existing systems.

I’ve also had a great deal of experience with New Zealand made – Perreaux, Plinius and more, and nothing I’ve heard in the past has had anything like the impact of the PRA with its resolution – while the NuPrime costs appreciably less than any of these options (especially when you look into the past and adjust for inflation), there is every reason to see the PRA as a great upgrade breathing new life into both your existing power amplifier and system. There is absolutely no downside.

There is a tier of imported models which, depending on your viewpoint, offer an affordable alternative to NZ made – the aforementioned Quad, Linn, Rotel, NAD and AudioLab being obvious examples that we have dealt with in the past. The NuPrime AMG, while similarly priced, works at a whole new level – the lucidity and openness will astound you. In many ways the AMG is the product that Quad should be building – it’s got an obvious debt in terms of the compact, simple aesthetics and the bass control. Again, in terms of compatibility, you can match the NuPrime with any power amplifiers from these designers. The gain switching, provision of both balanced and RCA outputs and tonal adjustment mean it will fit right in.

Because they have always been a benchmark for me, the Audio Research preamplifiers have to be mentioned – these were my first experience of a truly high end amplifier and proved convincingly that the quality of a preamplifier within a system has a huge effect – far greater than jumping between power amplifier models of different ratings. Both solid state and tube models produced cinematic soundscapes, the authority and dynamics are unforgettable. The NuPrime doesn’t work on quite the same scale which, given the massive disparity in specification and price, isn’t surprising.

But the NuPrime does give you some insight into this world – the lucidity and detail do approach this ideal and I think that the much higher input impedance of the AMG goes a long way towards getting more out of source components. Like Audio Research, NuPrime convincingly establish the preamplifier as they key component within an analogue system.

In the analogue world, we do have a degree of tolerance for quirks and variations that you don’t see in a digital environment. The vagaries of cartridge and turntable set up, surface noise, the odd hum and pop are just part of the organic charm of vinyl replay. On one hand the PRA does a lot to reduce these but (at least in my first of the line samples). there are a few idiosyncrasies.

It does generate a couple of switch-on clicks as relays kick in and, depending on the efficiency of your power amps and speakers these may be quite noticeable. The obvious solution is of course to turn your power amps on after the PRA. I’ve not been too worried about this as it’s well below normal replay levels so there’s no risk to speakers. There are also lesser clicks when switching between inputs but the mute function on the remote control takes care of this if it’s a problem for you. As with other NuPrime products I know that there is always some compromise in terms of muting and with a number of their power amplifiers they have made a conscious choice to concentrate on performance and keeping the end price down.

The extra resolution and gain will make any incoming noise issues you have a little more obvious – if nothing else this may make you look more carefully at grounding, the interconnect cables from your turntable, various power supplies and the relative positioning of all these parts. The PRA itself is reasonably quiet – because it has gain, it will amplify any incoming noise but it’s well isolated from power-line and environmental noise.

The first edition of the manual is light on detail – I’d love to see a full section on the bass management, an explanation of absolute phase switching and more about the design process behind the preamplifier. The remote functions likewise. But on the other hand the PRA is a reasonably simple component and it doesn’t take much to work out what everything does.

What the NuPrime does sound-wise is absolutely compelling and far outweighs any minor, and probably already resolved, quirks that I’ve found. It’s a component that I’ve been waiting for, specifically to bring our analogue systems up to where I feel they should be.

NuPrime AMH PRA & Waxy
The NuPrime AMG PRA and Consonance Wax Engine turntable.

The performance gain relative to the price is exceptional – when I look at all the other possible things we could do for a similar investment, I hear a greater and more obvious improvement from the PRA than any other part of the analogue chain; turntable, cartridge, phono stage, power amplifier speakers or cables. This is no mean feat as I’ve been deeply impressed by the progress made in these areas.

The PRA makes any attached power amplifier sound ‘bigger’. While the actual amount of power on tap doesn’t change, the PRA sends a more dynamic signal in – there’s more going on in every regard and this works both in terms of quality AND perceived power. Not only does this breathe new life into existing power amps it also make the differences between power amplifiers more obvious.

A case in point (which I’m going to expand upon in Part 2 when we look at the PRA’s performance in the context of digital systems), is with the NuPrime MCX-2 and Evolution One power amplifiers. The MCX-2 is a real favourite of mine combining what seems like an absurd amount of power (550 watts), with a particular live sounding signature. The PRA only enhances this and the greatly improved detail shines through making me like this amp even more. But it also clearly showed me the improvements wrought with the Evolutions – previously I thought there were some things the MCX did that the Evolutions didn’t but now with a better input it literally becomes clear.

Conversely the impact made by the PRA to the MCX sound is (from my listening so far), perhaps greater than it is with the Evolutions – I’m picking that because the Evolution Ones already feature a 1M Ohm input impedance like the PRA, they are already exhibiting some of what I hear with the PRA. Confused? Not really – I’m just working through all the possible combinations.

Again – this also points us at the matching AMG STA power amplifier – like the Evolutions it has a 1M Ohm input and runs at a switching speed of 700kHz. Everything I’ve heard so far suggests that the AMG PRA + STA combination will be a seriously high-end sound while the PRA + MCX gives us both quality and giant killing power. NuPrime are possibly giving us too much choice but when has that ever been a bad thing?

 

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So – is the NuPrime AMG PRA analogue preamp for you? If you have an existing pre and power system my unequivocal reply is yes – it’s effectively in a field of one when it comes to straight sound quality and is much better than any other preamplifier I’ve heard unless we want to go completely crazy price-wise. More to the point the PRA really is a taste of the high-end. The lack of digital inputs is a non-issue as I’m going to show in part two.

The PRA will physically fit in any system, runs cool and has plenty of scope for adjustment. In combination with almost any power amplifier it’s working at a level far beyond any integrated amplifier – it completely encapsulates the logic behind separating pre and power sections by redefining transparency, eliminating compromise and giving almost limitless flexibility.

Nuprime AMG PRA analogue preamplifier NZ$2850

We could say mission accomplished and for my own analogue listening, it’s hard to see where I’d go from here. But I have also found that the NuPrime PRA has some real potential in Digital systems and so will explore this with you next in Part 2.NuPrime AMG PRA angle

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