NAD 3020B: Keeper or Clunker?

NAD 3020 where it should be: In our rack!

Been a while since I last posted on anything audio-related – I’m taking that as a good sign because I know I’ve been enjoying a *lot* of music lately.

NAD 3020 where it should be: In our rack!
Our NAD 3020B in use. (Please forgive the poor photo!)

Many an audiophile posting online has an extremely polarised attitude towards the humble NAD 3020 series of integrated amplifiers, which seem to be very much a “love ‘em or hate ‘em” box. I always thought I was in the “love ‘em” camp, but until I inherited a 3020B from my father at the end of last year I never quite knew why. It’s not been the easiest of journeys, so please bear with me as I try to explain what I’ve found and what was going on at the time I found it.

If there’s any one lesson to glean from this experience, it’s that getting hifi sounding good is as much about the interaction of components working together as it is about finding of well-engineered components and slinging them together according to a spec-sheet.  These are also differences that I feel can make or break a system over the long term, but may not be immediately identifiable in typical demonstration arrangements that most stores can offer.

When inheriting our current system, my intention had been to replace my existing components one-by-one so I could check how the sound was changing at each stage on the way. I first swapped the speakers, as mentioned in another post. I then started repairing and using the record deck – plenty of other posts on that particular subject. With that now mostly bedded-in, i’ve come to the final part – using the 3020B.

Build quality

As a whole the unit feels well manufactured. Years of dust needed cleaning out of the phono contacts before connecting anything, but the speaker output binding posts are firm and accept 4mm banana plugs without modification – this amplifier was made in the generation(s) before the EU got their teeth into manufacturing regulations in the mid-90’s.

The source-select buttons are known on this series to be of slightly cheap construction, resulting in the plastic caps flying across the room when a new source is selected. Also, the source input sockets are somewhat loose.  This might be a result of their PCB flexing slightly when connections are made, or it might just be that the dimensions tolerance of the sockets themselves isn’t quite right. Again, this is a common flaw with amplifiers of this series, perhaps even of this generation.

The switches operate silently so far as the audio path is concerned, and the Bass, Treble, Balance and Volume pots/knobs also operate silently – rather impressive for such an old unit, especially if it’s ever been exposed to cigarette smoke, pets, small children and life’s little accidents as I know this one has.

Overall this unit is in better physical condition than I could have asked for – some surface grime aside, it’s basically unmarked except for the small hole drilled into it side where an intruder-alarm used to have a line threaded through it as a crime-prevention method. It’ll be an extremely rare find on Ebay that turns out in such good condition.

Sound quality – Take 1

Used with the Tannoy Mercury M20 loudspeakers it had been paired with in its previous home, the first impressions were that it is far warmer in tone than the 302 I was comparing it to, even with all tone controls at neutral and the loudness control off. Bass has more depth, stereo imaging is wider and deeper, but treble felt like a veil had been placed over the speakers.

Some experimentation with the Soft Clipping circuit showed no audible difference whether it was switched “in” or “out”.  I prefer to be safe rather than sorry, so I’ve left it “in” for now.

Another interesting experiment was to assess any audible differences between using the “Normal” (Low and High-pass-filtered) and “Lab” (Unfiltered) power amplifier inputs.  Theoretically the “Normal” input should be used, to filter out frequencies below 20Hz and above 20KHz, enabling the amplifier to use all its power in the audible frequency range and to run without interference.  The “Lab” input sounds better to my ear – soundstaging feels more solid, and the tonal balance a little more accurate throughout the entire frequency range. (See the first comment on this post for more about the correct selection of “Normal” vs “Lab” input).

Even having worked out which signal path to use, and to avoid the “Loudness” button, the amplifier was still not producing an overall sound I thought I could live with.  I therefore started to do some tweaking to work out where the “problem” was, if only to understand what was going on.

Experimenting with Pre/Power amp combinations

Both the 302 and 3020 have pre-out and power-in socket sets, allowing either to be used as the power amp for the other’s pre-amp section. First of all I wanted to see if the older 3020’s pre-amp section was the cause of the slightly muted treble. Some re-plugging later, I had both CD and LP feeding the 3020 pre-amp section, which in turn was wired to feed the power-amp of the 302. This combination had narrower imaging, slightly leaner bass, and still the soft treble that felt like it was hiding something.

Next I swapped the amp sections round, with the 302 pre-amp now feeding the much older power-amp section of the 3020, and everything seemed better. The soundstage was locked tight between the speakers for centred instruments and vocals, but there was much freer reign for anything panned between and even outside the speakers to be given space to do their thing. Either amplifier seemed equally capable of playing ‘depth’ information in recordings that have it, and so this was the way I left the units set up for some weeks while I got settled with the record deck and its cartridge.

Listening to the Tannoy’s through the 302 (using both its pre and power sections) I thought the sound was nicely tonally balanced, but always felt like I was listening through an imaginary window that the box placed on the musical world being painted in front of me. Conversely, the 302-pre and 3020-power combo gave slightly more extreme bass and treble presence, and effectively took away that windowed effect while fixing the veiled treble of the older amplifier used on its own.

System changes – a second chance?

Having settled on using the 302 pre-amp and the 3020B power-amplifier, a couple of things changed. First off, I found the new complexity of the system somewhat frustrating, but were willing to live with it if that’s what was going to give us the best overall sound. Then came the other major shift in our listening; I upgraded the phono cartridge to a Denon DL-160 MC (High output), seeking more accuracy of sibilants and better soundstaging. This much I got, but then many recordings were now too bright. Whether this was a result of longer-than-optimal running times on some discs, or perhaps due to an active mastering decision, I’ll likely never know.

Phono stages

With the new cartridge in place, switching between 302 and 3020 phono stages showed the differences between them were surprisingly subtle, but the older stage won out. It seems to reveal more midrange detail than the newer design, particularly with female vocals.  There’s also a lot more information being played from the background of mixes, better rendering things like room ambience and reverb tails. It also has better overall dynamics, and the soundstaging is a little deeper and wider.

This surprised me, since on paper the older design looks like it should perform worse than the new one. For one thing the signal-to-noise ratio quoted by the manufacturer is slightly higher in the older design, and I would expect its component tolerances to have drifted enough with age and use by now to have a significant negative effect, likely leading to loss of high-frequency detail and increased noise.

Just one side-note on the 3020 phono stage – it has two modes, one for MM (Moving Magnet) cartridges and the other for MC (Moving Coil) cartridges. MM carts typically have higher output levels than their MC siblings, but our MC is a “high output” model, compatible with conventional MM stages. Having tried the unit in both modes, neither sounds different than the other, even when the setting is “wrong” for the kind of cartridge in use. The phono stage shows ample headroom – I did experiment with using the MM cartridge with the extra amplification of MC mode and could hear absolutely no evidence of added distortion, even with discs mastered with very high recording levels. Further, using the MC mode with its extra gain ought to bring more measurable background noise into the mix, but I’ve yet to hear this in practise.

The 3020B on its own – Take 2

I decided to give the amplifier a second chance to fly solo, with vinyl as the primary source. Soundstaging now sounds wonderful with well-mastered discs in good condition – Pink Floyd’s “Dark Side of the Moon” and Eric Clapton’s “Slowhand” show a lot of their natural recording ambiences.  Newer, more synthetic recordings like Enya’s “Watermark” or Jean Michel Jarre’s “Revolutions” sound as modern as their source material and production values should present, with the end result sounding always convincing and really very human. Every instrument and voice has its own space in the mix, with no particular instrument or frequency range standing out above any other.

Poorer or duller discs can easily be improved with an adjustment via the tone controls. The effect of the tone controls is subtle but effective – I don’t feel like either circuit (Bass or Treble) impedes any other aspect of the sound passing through it other than whatever I’m telling it to do. Most bass-light recordings are usually too heavy in the treble, so a slight treble reduction usually brings things back into perspective. The inverse tends to be true if a recording is bass-heavy – usually a slight treble boost evens things out.

Turning to digital sources, playback again felt like it was lacking some treble at first, and the soundstage was somewhat vague. For most TV and DVD content we watch this isn’t a bad thing, and easily fixed with a slight adjustment to the treble control.

With playback of CD or downloaded content from our EMU 0202USB, it seemed that while bass and mid-range were coming through with much more timbre than I’ve been used to, and a much more even tonal balance, the high-frequency content was being reduced slightly, and felt slightly hazy, if such a term can apply to audio.

Having noted a slight increase in treble response over the few weeks the system lived in this new state, I’d have been happy to leave it there, concluding that either the increased usage had brought some components and connections back within tolerance, or (more likely) my subconscious processing of what I’m hearing was adjusting to the new system.

But then I made a discovery:  I could change the settings to run the DAC at a much-increased sample rate of 176.4KHz and 24-bit, with internal volume processing being done in the computer at 32 bits. This had the overall effect of giving slightly more audible treble, but more importantly it gave a lot more definition and control to the treble content.

I’ll likely write separately about this transition, but it really does take the digital playback to a level that competes with the best of what our vinyl source can give us. Listening to Royksopp’s “Senior” album for example, bass frequencies go into (and possibly below) sub-bass territory and the system keeps up, resolving the basslines with good speed – at no time does any bass note feel like it’s stopping later than it should. Synthesised kick drums tend to have very short attack times, and these are resolved wonderfully, the tonality of each kick drum making even different synths identifiable.  This is something I’ve never experienced before.

Remastered recordings I’ve complained about before (Al Stewart’s “Year of the Cat” and Genesis’ “Trick of the Tail”) are still a little too treble-heavy for my tastes, but have huge amounts of spacial and vocal definition, and are finally on a par with the original vinyl releases of the same albums.

Conclusion?

Based on some very practical testing, done by ear and confirmed with others who were unaware of the tweaking going on behind the scenes except for the cartridge upgrade, I have concluded that my 3020B is very much “a keeper”. Its warm tonal balance is generally flattering and does not interfere with the finer details of dynamics, soundstaging and definition. It is certainly able to show up any flaws of the recordings and source devices it’s amplifying. I think it fair to surmise that it does a good job with entry-level devices as they come out out of the box, but it does a truly great job when fed with higher-end devices, whatever form they would take.

Dual 505-2: Taming vinyl sibilance

I’ve been really happy with our record deck since we inherited it a few months ago, but one common problem has been playing back 70’s and 80’s pop/rock LP’s that have been, shall we say, well loved.  I had an idea while last re-aligning the cartridge/stylus that part of the treble reproduction issue I’ve been experiencing with these discs was that the cartridge was slightly vertically offset in comparison to the vertical alignment of the groove – almost as if the cartridge mounting is somehow twisted slightly on the arm.

The Dual 505-2 has no azimuth adjustment to speak of, but the cartridge is held in with a pair of bolts, and so the azimuth could easily be corrected by inserting a washer or some other small object to act as a shim.   I didn’t have any washers to hand that were less than 1mm thick (way too thick for this project), so for the sake of experimentation I’ve experimented with a piece of copper tape retrieved from a no-longer-working hard drive enclosure.  It’s less than 0.25mm thick, and easy to cut and fold to the right height.

To get a rough measurement of what was required, I chose an older duplicate disc and set it playing, and observed the end of the cartridge right above the needle riding the groove.  I estimated that the left side of the cartridge (as it faced me) was about 0.5mm too high compared with the level of the LP spinning underneath it, so I cut a small piece of the copper, folded it to get the approximate thickness required and cut a bolt-hole through it, before inserting it between the cartridge and its mount.

After doing up the bolts and re-checking the overall alignment, I started the same disc playing and listened.  Much of the treble harshness had gone, and vocal sibilant distortion was down around 50% – much more listenable for some of the older discs in our collection.  What’s more, newer/cleaner discs are sounding much more dynamic, and their overall soundstage much more focussed – much more digital, one might say.  Bryan Ferry’s “Boys and Girls” was a particularly problematic recording, but was much improved in this evening’s round of listening tests. The same improvement was noted on playing a slightly ratty copy of Michael Jackson’s “Thriller” LP.  We’re closer to hearing the music, and further away from hearing the equipment playing it.  That’s a good thing in my book.

Next on my list is to trim the copper shim to make the installation invisible, but it certainly proved my little theory and proves a nice illustration for anyone else wanting to try the same thing.

Mini-review: Tannoy Mercury M20 hifi speakers

I have Dad to thank for my love of all things hifi and all things musical – and somehow in December he agreed to let me give a new home to the core components of the hifi system that started it all.

The components I’ve grabbed so far are:

  • Pair of Tannoy Mercury M20 speakers, with matching Target spiked stands
  • NAD 3020B amplifier
  • Dual 505-2 turntable

After unloading, I figured the mains-powered electronics would need some time to warm up to prevent condensation due to having spent four hours in the boot of a very cold car causing problems. So the first thing I did (after pouring myself a hearty Whisky Mac) was to get the speakers running with my existing gear – a 15-year-old NAD 302 I bought new in 1995, fed by iTunes played at 88.2KHz 24-bit through an EMU 0202USB audio interface from an elderly second-generation iMac.

To provide a reference point: my previous speakers were an unknown-model 3-way Magnat design, each employing a 1″ metal tweeter, 2″ high-mid paper cone, and an 8″ mid-bass treated paper cone. These were themselves a bit of a bargain when I found them. The cabinets about the same size and shape as the Tannoys, and when purchased new I would guess they were at similar price-point.

I’ve grown used to a slightly over-loud treble from the Magnats – perfect for the room I originally bought them for, but not so good in larger, more open spaces with less damping, such as a typical open plan living-room/kitchen/dining-room that they’ve served for the last year or so. Though well-extended, the Magnat’s treble delivery doesn’t quite sound ‘real’, and they could have trouble delivering a stable, centred lead vocal. Since each cabinet measures the same response using RTA/pink noise, and the drivers/cabinets are undamaged, I’ve yet to find a cause for this. Otherwise their sound was slightly warm and reasonably accurate, though I did find myself removing the bass-port tuning tubes to provide a more natural, dynamic bass-line. Curiously this also extended the the audible bass response by another octave.

By contrast, the Tannoys are a two-way design using a 1″ silk dome tweeter paired with a translucent white plastic 8″ mid-bass driver. Their sound is much warmer and smoother than the Magnats, with well-defined bass-notes that don’t noticeably allow any one bass note to play louder than any others. Upper bass notes are actually slightly less prominent than I’m used to, but there is a stronger and more accurate response below 100Hz, allowing kick drums and sub-bass lines to underpin the mix even at very low volumes. The sub-bass lines of any material I’ve played through them have shown they can keep up with the rhythm of even the fastest Prodigy or Underworld tracks, as well as allowing movie soundtracks enough bass to not need a sub.

What I remembered about these speakers in their original home was that they hold their soundstage together at extremely low volumes – this bodes well for micro-dynamics at more normal listening levels, but also allows for very enjoyable late-night listening when everyone else has retired to bed.  At more ‘normal’ listening levels (around 60-90dB depending on source and time of day) these speakers really come into their own, painting a very natural image and revealing the differences between recordings like nothing else I’ve spent significant time with.

I would say the real magic with these speakers has to be the way they present vocals. They don’t do the usual high-end hifi fancy trick of making the vocal sound like it’s right in front of you and about to take your face off – and I’m aware that some might say this is a bad thing. Instead, they present vocals in a way that seems effortless and yet somehow forces me to hear every last word, and they seem to do this without obviously emphasising any particular frequency range commonly associated with vocal intelligibility. It’s almost distracting at times – a song playing in the background suddenly demands attention in a way I’ve not experienced before. That is a stunning achievement now, but somewhat surprising considering I’m listening to boxes made some 25 years ago. Really, my only criticism of these speakers is that the treble doesn’t seem to obviously reach as high as I’d like. Anything above around 13KHz seems slightly muted.

This has been a lot of fun – these are speakers I can live with for daily use, yet are revealing enough to tell me when something’s not right in the recording or the playback chain.

And finally: thanks Dad, for letting us rob you that Saturday afternoon!

Update – 5th January 2013

Turns out that the speakers we have may not be the “Golds” that we all initially thought they were.  Ours are single-wired and marked as Mercury M20 in a gold logo at the bottom-right corner of each speaker.  The M20 Golds I’ve seen recently were biwirable, and featured black-plastic mid-bass drivers in place of the white units in ours.  I’ve therefore updated the model references in the article and the title.

Whether or not ours are really “Gold” or just standard M20’s, nearly two whole years have passed since the original posting, and I stand by my comments about the sound of our examples – and I’m not looking for replacements anytime soon!