altBelow is the complete review as published in Australian Hi-Fi Sep-Oct 2014. For the original magazine pages, including the full Lab Report and graphs, download the PDF version by clicking the button on the left (3.55MB).  

 

altNAD D 3020 integrated amplifier REVIEW

It is not unknown for some canny marketing types to ‘leverage’ old model numbers to stimulate sales of new and often completely different products. This marketing tactic involves releasing a new product with the same (or very similar) model number as a product the company previously sold that was popular with consumers.

One example of this in the automotive world is Nissan’s ‘Z’ series of sports cars. The current Nissan 370Z started its model life as the Datsun 240Z, a model that was so phenomenally successful for Nissan that when it ‘retired’ the Datsun marque, it deemed it essential to keep the ‘240Z’ numbering system to ensure the continued success of the model. So the 240Z transitioned to become the 260Z, then the 280Z, and so on, but even Nissan’s latest numbering schema still contains the ‘DNA’ of the original model number. (The actual car, unsurprisingly, bears very little resemblance to the original… inside or out!)

NAD has taken very much the same approach with its new D3020 integrated amplifier. The original NAD 3020, released back in 1978, was designed as a flag-bearer for a company that had recently re-badged itself (from the rather clumsy ‘New Acoustic Dimension’ to the tight and catchy ‘NAD’). The amplifier was deliberately both over-specified and under-priced (at least according to the hi-fi equipment reviewers of that era). The result of these strategies—not to mention the fact that it was a bloody good little amplifier!—was that the NAD 3020 was a run-away success story for NAD.

The company sold more than a million 3020s, which made it the best-selling amplifier of its time and it’s still fondly remembered even now, regularly getting mentions on listings such as ‘Best Amplifier’, ‘Hot Products’, and ‘Ten Most Significant Amplifiers of All Time.’ Recognising a good thing when it saw it, NAD leveraged the 3020’s popularity by following up with similarly-named models, such as the 3020A, 3020B, 3020E, 3020i and 3120.

altUnlike all previous 3020 variants, which used entirely linear power supplies and linear output stages, this new D3020 uses switching circuitry: both a switch-mode power supply and a Class-D output stage. For the record, although most audiophiles refer to Class-D amplifiers as being ‘digital’ (even I’ve been guilty of it on occasion), they’re not really: a Class-D amplifier is simply just a specific type of analogue amplifier. It’s probably most correct to call Class-D a ‘switching’ amplifier, which is why I have done so, using the authority of none other than the famous Bruno Putzeys, an expert in Class-D design (he invented the self-oscillating version that’s used by Hypex) whose own definition of how a Class-D amplifier is that it: ‘operates by deriving a discrete-state signal (usually two-state) from a continuous control signal and amplifying this using power switches.’

As you’d expect from an amplifier made in the 21st century, the D3020 also has onboard aptX Bluetooth circuitry to enable wireless music streaming from a Smartphone or other Bluetooth-equipped device, as well as an asynchronous 24-bit/96kHz USB input, so you can play back computer-based music from a desktop or laptop (or wired from a portable device).

The Equipment
Although I have seen some photographs (in print and on the web) which show the D3020 oriented horizontally, the designers intended it to be mounted vertically, not least because the D3020’s display is on the top of the unit, and the cooling vents are on either side. (It would appear that the ‘horizontal mounters’ have taken their mounting cues from the writing on the rear panel, which appears to indicate the unit should be horizontally mounted. I would not personally recommend this, not least because it blocks off one of the cooling vents.)

Before 240V mains power is applied, the NAD D3020 appears not to have any controls at all, save for the large (and rather wobbly… at least on my review sample) rotary control protruding from the front panel. However, after you’ve powered-up, sections of the previously-dark Perspex on the top and front of the D3020 light up to reveal that the top surface of the amplifier is a touch-sensitive pad that allows you to turn the power on and off—and select input source—while the front panel is a display that indicates the input source you’ve selected and the current volume level. At the bottom of the front panel is a 3.5mm headphone socket.

altThe rear panel is clearly labelled and has full-sized, gold-plated multi-way speaker terminals despite the limited space available. There are two SPDIF digital audio inputs (one Toslink optical, one via gold-plated RCA), one USB input (via a Type B terminal) and two analogue inputs (one via a pair of gold-plated RCA terminals and the other via a 3.5mm stereo socket). There’s also a subwoofer output terminal, again implemented via 3.5mm phone socket. (Such small phone sockets aren’t my favourite connectors, as they’re not overly robust mechanically, but NAD obviously didn’t have the room for larger ones).

Also on the rear panel is a triangular-shaped 240V input socket (à la Hewlett-Packard), and a 3.5mm 12-volt d.c. trigger input.

If you look at a photograph of the rear panel, you might be confused (as was I) by the fact that the ‘Aux 2’ terminal is also labelled ‘Optical 2’. After looking in the Owners’ Manual, I went back to the packaging I’d stored away and discovered the Toslink mini-adaptor NAD provides that converts this analogue wired input to a digital optical one.

While I had the Owners’ Manual out, I took the opportunity to look up the purpose of a tiny button (and with a diameter of only 2mm, I think I can safely call it tiny) labelled ‘Bass EQ (Service)’ that is recessed into the rear panel so deeply that you can’t accidentally operate it (though you can still do so with a finger: you won’t need a ballpoint pen). It turns out that although the D3020 does not have tone controls, it does have a Bass EQ button that, according to NAD’s aforementioned manual, will: ‘Boost overall bass response by at least 6dB.’ And when you push the button, the word ‘BASS’ appears on the front panel.

Internally, NAD uses a particular implementation of Class-D amplification which it licences from the well-known Dutch manufacturer Hypex. Hypex markets two different ‘flavours’ of Class-D: UcD (Universal Class-D) and N-Core, of which two NAD is using UcD. ‘The UcD is a very innovative analogue Class-D amplifier that is self-oscillating and uses a variable modulation frequency based on operating conditions,’ said Björn Erik Edvardsen, who not only designed the original 3020 for NAD, but also this new D 3020. It’s superior to most other Class-D technologies because of its load invariance, which means its sound doesn’t change with different speaker impedances; it’s unaffected by very low impedances; its loop gain is constant over the full audio frequency range (leading to low distortion even at high frequencies); it can be constructed using discrete parts (so no need for expensive control ICs); and distortion is extremely low even into low impedance at high frequencies. Edvardsen says he has further refined the circuit’s performance by upgrading the output FETs and reconstruction inductors (by using low-saturation cores) to allow more current delivery when using low-impedance loads. The power supply is a stiff switch-mode supply featuring synchronous (active MOSFET) rectification that eliminates supply pumping, which is an undesirable failing exhibited by most single-ended Class-D amplifiers. ‘It also benefits from the latest refinement of NAD PowerDrive, our exclusive circuit that gives phenomenal performance, both measured and subjective,’ says Edvardsen.

The remote control that comes standard with the D3020 is quite small (and so likely to be easily lost… at least in my household), and completely black. That is, not only is the remote itself black, but also the buttons, which makes identifying them rather tricky. However, since you’re really only ever going to use the volume up/down buttons and the input source switch (plus the power on/off) familiarising yourself with the button layout should be quite easy. (And if you’re visually challenged, there are indents to allow you to identify the keys by touch alone.) Although the remote’s ergonomic design has some minor short-comings, we should be grateful that NAD supplies a remote control at all: many amplifier manufacturers (including more than a few high-end ones) now charge extra for their remotes.

Although the NAD D3020 comes with an Owners’ Manual, I was very impressed with the website NAD has built for the D3020, which has pdf versions of the manual in five languages, plus a ‘Quick Set-Up’ guide in English. There are also pdf versions of the D3020’s datasheet, a copy of an NAD ‘White Paper’ concerning the D3020’s design, a list of the codes used by the D3020’s remote control, plus two downloadable software programs: a firmware update for the D3020 (currently in Version 2.4) and a USB audio driver.

altIn Use and Listening Sessions
NAD has cleverly arranged the speaker terminals so you should be able to wire your speakers neatly using bare wire, with minimal ‘wire show’, but I would personally recommend you use dual Pomona terminals to connect your speakers (or, if you prefer, individual banana connectors). However, because the unit is so narrow, if you do connect a full complement of inputs and outputs, you’ll have quite a bit of wire showing behind the amplifier. Nonetheless, please resist the temptation to re-orient it horizontally!

The D3020 can be set to automatically go to standby mode (in which it draws less than 0.5-watts of power) when there is no active source. If set for automatic standby, it will enter this mode after 30 minutes of not sensing an input signal, or anyone using the controls. I am a great fan of saving power, but I also have a love–hate relationship with auto standby controls, because some amplifiers will ‘wake up’ from standby mode only if the remote stand-by button is activated (which means you have to know where it is… see my earlier comment about NAD’s remote), or if the mains power button is switched ‘off’ then rapidly pushed back on. Both systems annoy me (irrational, but true!). The D3020’s remote can certainly be used to re-activate the amplifier, but you can also do it by simply holding your finger over the ‘Power’ button on the top of the amplifier. This action is OK by me. Happy with this! (If you’re not, at least you have the option of setting the D3020 so it never turns off. Don’t imagine you’ll be wasting power, either, because the power draw when idling is less than 20-watts.)

Some users (and I was one) might find switching between inputs a little ‘clunky’ because of the touch sensor, but it’s not hard to keep up with what’s happening by using the front panel read-out. Repeated touches on the top panel result in the input cycling round in the direction: OPT1, OPT2, Coax, USB, Aux1, Aux2, BT. (This sequence runs ‘top to bottom’ in the display). In the event that you do switch the D3020 to standby (or it drops into standby automatically) it will re-select the last-used input upon switch-on, as well as the last-used volume level. Nice!

altNot-so-nice was the rather ‘spongy’ feel of the volume control and the front-panel display of volume level which has markings for only six levels (–100dB, –80dB, –60dB, –40dB, –20dB and 0dB). In practise, however, you’re more likely to use the remote to adjust the volume level, and although the display gives you a rough idea of the volume level, rather than an exact numerical readout, it ‘does the job’, as they say. (Although there are only six levels indicated, the display varies in brightness as you go from one level to another, so there are nuances you can pick up on. However, although you can see these nuances in display brightness as you’re actually adjusting the volume level, if you just come into the room and look at the display without touching the volume control, it’s difficult to work out the level that’s been set.) An accurate read-out of volume level would be more important if the NAD D3020 had a mute button, but it doesn’t, so it’s not so much of an issue. And if the lack of a mute button bothers you, just leave one of the six available inputs unused and switch to that whenever you want to ‘mute’ the sound. (Since the D3020 is firmware-upgradeable, it is feasible that NAD could ‘add’ in a Mute button via a firmware upgrade, even for existing models. If NAD thinks this is a good idea, I’d suggest using the play/pause button, since it’s not used for anything else on the D3020. Check with your dealer to see whether this upgrade has been implemented.)  [STOP PRESS: The NAD D3020 now DOES have this mute function, activated and deactivated by using the play/pause button on the remote. Older units, can add the mute function simply by upgrading the N3020's firmware.]

It seemed to me that the most likely customers for the D3020 would be those creating desk-based systems to provide high-quality computer-based sound, and those creating minimalist hi-fi systems, probably using NAS storage or streaming from their phone. My assumption was that it was likely that such customers would have high-quality, two-way bookshelf/stand-mount speakers, so most of my listening was done using such speakers (though I did take the time to audition the NAD D3020 with two pairs of large, floor-standing loudspeakers).

Having experienced high-quality Class-D amplifiers previously, I was not surprised by the amount of power the D3020 was able to deliver, but if you haven’t you will certainly be surprised. It’s amazing that such a physically small amplifier, without any visible heatsinks, can produce such deafening levels of sound. However, having experienced Class-D amplifiers previously, I was absolutely amazed by how good the D3020 sounded, particularly across the midrange and up into the treble. As I swapped speakers in and out, I was also surprised by the fact that the sound quality and volume level of the high frequencies remained constant no matter what speakers I used. Previously, I have found that the high-frequency sound of Class-D amplifiers I have evaluated in the past changed considerably depending on the speakers being used, so that speaker choice became critical in determining the ‘sound’ of the amplifier. This definitely did not occur with the NAD D3020. Its high-frequency sound, in particular, will remain identical irrespective of the speakers you use with it. And that high-frequency sound is excellent! Its level was always perfectly balanced against the mids and it was also unerringly clean, with no distortion, no high-frequency noise and no audible h.f. ‘clutter’ .

This lack of clutter and the crisp high-frequency sounds were demonstrated beautifully on Mikhael Paskalev’s recent strangely-named album ‘What’s Life without Losers?’. Listen to the acoustic guitar intro to Woman and you’ll know immediately what I mean. The clarity of Paskalev’s ‘unique’ voice is also reproduced accurately by the D3020. The same goes for the next track (Susie) even though the song, the music and the singing are totally bonkers. If you can last long enough to hear Brother (Track 9… and trust me, Paskalev really is an acquired taste!) you’ll hear that the NAD D3020’s bass delivery is super-solid and super-precise. No overhang, no unwanted warmth… just wham and slam whenever required. I did take the opportunity to try out the Bass Boost button. Its effect was immediately obvious and rather too overpowering for my tastes… at least with the speakers I tried. You may think differently, which is no doubt why NAD has made it switchable (and relatively inaccessible).

Once I had established that the NAD was a well-powered and good-sounding amplifier, I wondered if these traits remained true irrespective of how the signal was sourced, so I switched from using wired analogue signals to using Bluetooth, and then switched back and forth between ‘wired’ and ‘BT’ deliveries of exactly the same music. While I did have to express a preference for the hard-wired delivery of music, the two were so similar in sound quality that I’d be hard-pressed to justify this preference solely on sonics alone… because depending on the music being played, the differences were indeed small. The same happened when I used the NAD D3020’s USB connection, except that the differences became infinitesimally small. There’s certainly some superior D–A conversion going on inside the D3020.

Conclusion
In all the reviews I have seen of the NAD D3020 it seemed that most of the reviewers were intent on trying to compare it with the original 3020. Frankly, I think that’s a complete waste of time. Good though the original 3020 might have been, we’re talking about an amplifier that was designed and manufactured more than 30 years ago. Technology has moved on since then, NAD has certainly moved on… and so have the undeniable talents of designer Björn Erik Edvardsen. Indeed I suspect Evardsen would be quite offended if anyone suggested that he hadn’t learned anything about amplifier design in the past thirty-five years. In fact the opposite is true: Edvardsen has learned a lot since he designed the original 3020, which is precisely why we now have the D3020.

If you’re after a small form-factor, vertically-oriented amplifier that’s absolutely ideal for computer-based/streaming applications, NAD’s new D3020 is a little cracker. # Dean Shopes

(Note: A full laboratory test of the NAD D3020 is included with the pdf version of this review. You can download it HERE.)

NAD D3020 Integrated Amplifier
Australian Price: $699 (RRP)

PLUS Points For: Bluetooth, USB/SPDIF, vertical design

MINUS Points For: Only two analog inputs, touch panel, volume control

Warranty: Two Years

Product page: www.qualifi.com.au