German Physiks

HRS-130 Loudspeaker

£16,500

Despite the dazzling technological progress of the past few decades, we're still a long way from producing a perfect loudspeaker. There are many reasons for this, not least the fact that reproducing a treble signal at 10kHz accurately is a different challenge for a drive unit than delivering a clean 100Hz bass tone. That's why designers divide up frequencies between bass, midband and treble (or at least mid/bass and treble) and get purpose-designed drive units to handle each region. Then the problem of marrying these up is that they don't cross over near 3kHz, where the human ear is most sensitive. So rather like a fly splatting into your car windscreen right in your line-of-sight, it may only be small in the grand scheme of things, but it's in precisely the wrong place!

Countless speaker designs have tried to get around this, but few have really succeeded. One exception to this rule is arguably the £16,500 German Physiks HRS-130 floorstander. It uses a radical Dicks Dipole Driver designed by Peter Dicks, inspired by the work done by American engineer Lincoln Walsh in 1964. The DDD is smaller, simpler, easier to make, and has a much lower moving mass, higher sensitivity and is more rugged. The company was formed in Frankfurt in 1992 by Holger Mueller and produces a range of speakers, this being one of the more 'affordable' designs! It sports two drive units – the DDD at the top and a conventional 250mm woofer firing down just above the speaker's base – the former goes from 24kHz all the way down to 220Hz, with the latter taking over below that.

DDD THEORY

The way the DDD works is complex and requires some understanding of loudspeaker theory. When the voice coil of a conventional drive unit moves, the cone moves with it – sending the sound in the same direction as the cone is moving the air. Because the cone and voice coil in a conventional driver moves back and forth in unison, like the piston in a car engine, they are often called pistonic drivers.

A DDD behaves differently. At the lower end of its operating range, it operates pistonically, just like a conventional driver. There then follows a band of frequencies where radiation through pistonic motion is progressively replaced by radiation through bending waves. Bending waves in the cone occur because it is very thin and flexible. Whilst it maintains its conical shape at low frequencies, the increasing force exerted by the voice coil as the frequency rises eventually causes the cone wall to flex where it is connected to the voice coil and a wave to travel down the cone's wall towards its open end. As this wave travels faster than the speed of sound, it causes a sound wave to be radiated outwards from the cone.

Finally, the last mode of operation happens above the bending wave band at the dipole frequency, when the first standing wave occurs on the cone wall and modal break-up begins. Here the DDD operates using modal radiation. In very simple terms, what happens is that vibrating areas are established on the cone's surface that resemble the pattern of ripples you see when a stone is dropped into water. Each one of these vibrating areas acts like a discrete sound radiator. As the frequency increases, the size of these vibrating areas gets smaller, and they become more numerous.

Both bending wave and modal radiation modes provide a lower effective moving mass than when the driver is working pistonically, says German Physiks. This is because, unlike when the driver is operating pistonically, where the moving mass is the voice-coil and entire cone, in bending wave and modal radiation modes, the moving mass is effectively the voice-coil and the mass of the cone material in the wave at the point of launch. It is this reduced moving mass that is the key to the DDD's extensive frequency response. Furthermore, careful selection of the cone material and its dimensions allows these three modes to be optimised using powerful computer modelling.

The end result is an ultra-wideband driver that propagates sound omnidirectionally. A DDD is far less prone to producing a 'sweet spot' in the room, and high frequency beaming is said to be eliminated – so the tonal balance is more uniform across the room. Also, because the driver has a very low moving mass, transient response is better. Finally, as the driver works smoothly across nearly seven octaves, there's no need for an invasive crossover.

The HRS-130's DDD driver uses a cone made of extremely thin (0.15mm) carbon fibre, said to be very light yet ultra-rigid. Each one takes six hours to make in the company's German factory, after which it is tested and then subjected to a ninety six-hour 'pre-ageing' process. The woofer at the bottom of the cabinet works in a sealed enclosure, linked via a small opening to a smaller cavity at the top of the cabinet, acting as a Helmholtz Resonator. This is tuned to a harmonic of the bass cavity's first resonance, and because it is filled with damping material, it helps to smooth out a peak in the bass response that this resonance would otherwise create. It takes over from the DDD at 220Hz.

UP CLOSE

This is the second model up in the German Physiks range and measures a not inconsiderable 1,259x325x325mm (HxWxD) and weighs 34.5kg apiece. The cabinet is made from MDF with internal reinforcements fitted at critical points, and a thick layer of high density felt is applied to the inside of each panel. A sound-absorbing material called Hawaphon is also applied to the inside of each panel to reduce vibration and minimise cabinet resonances. This is a matrix of small cells filled with steel shot; the idea is that vibrational energy moves the pieces of shot against each other, converting the vibrational energy to heat. This is said to be highly effective at reducing vibration; the material's makers claim reductions of up to 50dB are possible.

WBT nextgen bi-wiring posts are fitted around the back, along with jumpers to alter the high-frequency output levels in four steps (-2dB, flat, +2dB and +4dB). Wood veneer or satin paint finishes are standard; my review sample came in high gloss polyester, which costs an additional £2,300, while carbon fibre is £3,450 extra. My overall impression of the review sample was very positive; it feels like a very high-quality product and is highly acoustically inert if you knock it with your knuckles.

German Physiks claims a frequency response of 29Hz to 24,000Hz for this speaker and a power handling of 120W. Sensitivity is quoted at 86.9dB/1w/1m, and nominal impedance at 4 ohms; this means you'll need a gutsy solid-state amplifier to drive it or a brawny valve amp – peak current delivery is key here. Plenty of drive means the amplifier can properly tickle the DDD driver, stirring it into action. Weedy ones will result in a flat, boring sound. My Sony TA-N86B power amp, with its 30W of Class A, wasn't quite up to the job, but a 150W RMS per channel Copland CSA-150 integrated showed no fear! Surprisingly perhaps, I found this speaker relatively easy to place – ideally, it needs to be over a metre from any wall; this is the main criterion when setting up.

THE LISTENING

Normally when I talk in terms of a loudspeaker having a distinctive sound, I mean that there's a particular aspect to its performance that stands out. For example, it might have exceptional bass power or speed, dizzying transient speed or excellent midband detail. The HRS-130 is distinctive in quite a different way because it doesn't particularly draw attention to itself in any way. Indeed, it's almost as if you have to unlearn the ritual of listening to a conventional multi-driver box loudspeaker. Rather like the best electrostatics, it instantly marks out the failings of regular speakers without celebrating itself.

That's why, on first appraisal, some people might actually call it bland. A well-positioned pair sets out the music before you, and you're sat there wondering where all the booming, squawking and fizzing has gone; you're also puzzled why the sound is uniform from top to bottom, and also why it doesn't change much regardless of where you are in your listening room. This is precisely the opposite of the 'shock and awe' that you get when hearing some big high-end box speakers, with their thundering bass, powerfully projected midband and incisive treble beaming out at you.

What is more, the representation of spatial information in a recording is remarkable, providing you've set the speakers up in the room correctly. They instantly home-in on where the singer was in the recording studio's microphone booth and/ or where the producer had placed their feed on the mixing desk. There's a laser-like accuracy to the positioning of voices in broadcast studios, too; it was almost as if I'd set up a secret spy camera in a BBC news studio when listening to World Service radio!

For these reasons, the HRS-130 is quite a remarkable speaker, yet it still won't be for everyone. It does some things brilliantly and most things rather well, yet its super-civilised sound simply won't excite some listeners. This is because it's not actively 'remixing' the music it's being asked to play. Indeed, feed it the energetic new wave rock of XTC's Making Plans for Nigel, and this speaker can sound too matter of fact. There's little in the way of bass boom, midband nasality or treble smear. Instead, you get a unique insight into the dry sound of the recording studio and the slight softening imbued by the late seventies analogue tape and mixing desk being used. When you've got over the initial shock of not being assaulted by banging bass, screeching upper mid and/ or sibilant treble, things become far more enjoyable. It's only then that you begin to appreciate this speaker for its many fine qualities.

It is as if the HRS-130 tears down the walls between the listener and the recording, then doubles back and hangs a very light, almost acoustically transparent black curtain between the two. Tonally this speaker is subtly dark and velvety; nothing ever screams at you, not even the light, bright, modern recording that is Coal Mine by Syd Arthur. This neo-psychedelic/ prog-rock recording channels the sultry late sixties valve-drenched sound of Caravan's In the Land of Grey and Pink but is actually a lot cleaner and modern sounding. It proved a pleasure to listen to via this speaker, even if there was a very subtle sense that the rough edges had been smoothed out.

Indeed one could argue that we have become accustomed to listening to the messy sound of drive units crossing over, and because this isn't present on the HRS-130, it can seem too silky. There's certainly something in this, as this speaker is seamless from bottom to top. With fewer distractions than usual, I was able to focus on the beautifully crafted electric guitar work; the texture of this instrument seemed to glint out from a dark void, such was its lack of colouration.

I heard the same on the brass stabs of Walking in the Sunshine by Bad Manners; this speaker made them sound fresh and smooth at the same time, rasping rather than screeching. This early eighties ska track conjured up a gigantic wall of sound. Despite it not being a particularly sophisticated recording, the HRS-130 conveyed its scale and atmosphere better than almost all other designs I have ever heard. The music seemed to emerge from a circular 'force field' around the speakers rather than a kind of two-dimensional electric fence between them.

It was even more so the case with Fine Time by Yazz, a tremendous late eighties dance single; this track has a massive synthesised baseline that chugs along, over which the singer's voice calls out mournfully. Again, I was once more surprised by the sheer scale of the occasion – the expanse of sound left to right and front to back. Contrast this to conventional high-end floor standers such as B&W's new 804D4 that I had to hand, and it was more like the latter was beaming sound waves at me, rather than circulating them ethereally all around. That is no small compliment because the latter is nobody's fool.

The genus of the HRS-130 is its smoothness, spaciousness and subtlety, then. Even with loud and histrionic classic rock records, it's able to convey a great deal of their appeal. The Who's Won't Get Fooled Again wasn't as viscerally impressive as similarly priced JBLs or Klipsches, but it doesn't set out to compete with these 'big bangers'. Instead, it works by gently drawing the listener in to enjoy the performance in a finer and more intricate way.

There are downsides, of course, as no speaker is perfect. The HRS-130 has a sweet spot in terms of listening levels where plenty of power is flowing into it, but it's not being expected to raise the roof. As high-end floorstanders go, it's not that large and simply cannot compete with significantly bigger designs. The Who track lives or dies by how hard Keith Moon bashes those snare drums and the zing of Pete Townshend's guitar power chords, yet these seemed a little subdued at very high levels. Of course, most conventional floorstanders with limited cabinet volume do just the same – so if you want ear-bending transients, buy a horn-loaded design.

I really enjoyed this speaker's bass, albeit a little different from the fray, like the rest of its performance. In my medium-sized listening room – with its admittedly imperfect acoustics – it generally sounded fulsome and solid, with a decent bounce to the proceedings. It certainly caught the taut, supple bass guitar work on Rush's The Camera Eye. Yet it's not quite the tightest and most taut around. In my case, I suspect that this is a function of the speaker's interaction with my listening room – which wins no prizes for its lack of resonant modes. I suspect the HRS-130 works best in seriously large rooms. In fairness, though, I have had other speakers working better low down – especially infinite baffle designs such as ATC's SCM40. Moral of the story? Audition a pair in your own listening room, if you possibly can.

This being said, the German Physiks never sounded less than highly enjoyable and insightful, with wondrous stereo imaging. No matter the programme material, the HRS-130 performed well across the board. From microdynamics and low-level detail resolution to spatiality, treble delicacy and timbral resolution. It did an excellent job of reproducing most things, giving insight into the music and the recording without getting too analytical.

Of all the music genres I tried, it shone brightest with classical. Here, its clean, open and natural sound – almost wholly devoid of colouration – was a revelation. The superb London Symphony by Ralph Vaughn Williams was an unalloyed pleasure, as the HRS-130 played majestically to all its strengths. What amazed me was its sheer resolution of the depth and breadth of the concert hall, with all the air and space inside it. At high volumes, one could virtually hear a fly land on the fire exit door handle. As the music began, the orchestra's unique sound was beautifully carried, and the music had a brooding, almost menacing quality as it built up to a crescendo. The timbre of acoustic instruments was a joy, as was the way the piece pushed along in a clearly rhythmic way. Dynamic accents sometimes felt like firecrackers going off, such was the intensity of the listening experience.

THE VERDICT

There are various great loudspeakers on sale at this price – all of which have differing visions of what constitutes superb sound – and the German Physiks HRS-130 is one of them. Of course, the best model for you is one that fits in with your taste, musical preferences, your system and your room – all of which are highly subjective. Yet, I can see many taking to this and loving it. Its engineering depth and build quality confer unique attributes that mark it out as an extraordinary high-end design.

Visit German Physiks for more information