Loudspeakers

Oh to live in a trendy warehouse conversion overlooking the Thames. Imagine the acres of glass, the polished floors and the designer furniture with the Habitat labels peeled off. One’s loudspeakers would need to offer equally stunning visual splendour, exude an air of bespoke affluence and leave your friends (probably called Tarquin and Jemima) green with envy. Clearly you would need Jamo’s sumptuous R 909s or if your City bonus has been a little credit crunched this year, perhaps the smaller but equally lush R 907s reviewed here.
   Meanwhile in a panelled living room on a farm in the backwaters of East Sussex, the R 907s ocular charms don’t make as much sense. Its ultra-contemporary style is a little out of place and the gloss black baffles had canine nose prints all over them within ten minutes of sliding each speaker from the single sturdy crate.
   Just as well then that the stylish, backless form is derived from the design’s dipole function. With no cabinet enclosure the drivers radiate a fairly even response to the front and rear. ‘The reflected sound from the rear adds ambience and gives the impression of a much larger room and a more lifelike live performance,’ says Jamo.

DIPOLES APART
Dipole speaker configuration is a subject that keeps bars at hi-fi shows open ’til 3am, with proponents for and against arguing their corner. On the one hand dipole designs virtually eliminate cabinet colourations, can reduce the effect of room nodes in the LF region and usually achieve a much more natural and spacious sound. Quad’s classic electrostatics are a prime example of the benefits of dipole configuration. Conversely dipoles lose the bass reinforcement benefits of a cabinet so tend to be bass-shy; they are less efficient at turning Watts into dBs and the freestanding baffle is less stable than a cabinet. Moreover, the reflected sound can confuse stereo focus and imaging. All very much like Quads classic electrostatics in fact.
   Jamo’s backless beauty addresses the down-side of dipole design in a fairly elegant way. Twin bass drivers of monstrous proportion and a tweaked crossover ensure a deep and substantial bass response. Both the 140mm magnesium midrange unit and the decoupled DDT tweeter (see box-out) are very efficient in a bid to ensure reasonable dB output per Watt input.
   And the R 907’s construction certainly doesn’t leave the planar-baffle with any stability issues. Its 45mm-thick frame is attached to a weighty cast base plinth and braced with an aluminium strut running top to bottom. This, in turn, is constructed of two sheets of aluminium coupled with spacers that leave just enough gap to hide the driver cables neatly between. Interestingly, only the upper of the two bass drivers is fixed to the strut.
   But perhaps the R 907’s most canny design feature is the tweeter arrangement. This is actually a decoupled device set within a sealed aluminium enclosure – and thus not a dipolar design at all. Theoretically this offers all the benefits of an enclosed cabinet tweeter with good front-facing response and none of those pesky rear-radiated HF waves bouncing off walls. Back at the bar at 3am, one could argue this will give the R 907 better focus and imaging than if it were a true full-range dipole design.
   Others will argue that a substantial reflected response across the HF spectrum is just what adds much of the space, air and ambience for which dipoles are famed. My personal opinion falls into the latter camp. Going to the trouble of creating an open-back speaker and overcoming all the inherent efficiency issues seems a whole lot of hard work if you then go and install a sealed-enclosure tweeter.
   What’s not up for debate is that the R 907 boasts superb build quality, fit and finish. Every component used stands up to comparison with those employed by speakers costing twice the price while the paint finish is impeccably smooth and mirror-like. Indeed, it’s even on a par with Focal’s ultra luxurious Grand Utopias for example.
   Often such a piano finish shows spider-web scratches as soon as you breathe in the same room, but I am pleased to report that the wet-nose prints polished off a treat. A full set of grilles for front and rear are supplied – presumably in case Tarquin and Jemima come to visit with their kids, Cousteau and Porsche.

ON THE MOVE
The only disadvantage to those lovely acres of high-gloss paint is that they show up finger marks with the efficacy of a CSI professional. Not a problem on a day-to-day basis for sure, but as you will spend the next fortnight moving the R 907s back and forth, in and out, and adjusting the toe-in angle you might want to keep a can of Pledge handy.
   Easy to position, the R907’s are not. All that rear-firing LF and midrange energy bounces around the back of the room like a pin-ball on steroids and the effect on the sound is enormously variable. On the path to the right speaker position I went through standing waves big enough to surf on, multi-path distortion that sounded like bad quadraphonic and surreal phase-timing issues that, for reasons I am yet to understand, made my eyes water.
   The Jamo manual gives good advice on where to start but this type of speaker is designed to interact with your room boundaries. It is no surprise that getting the speaker-room interface correct is going to be a variable feast. Through an in-depth trial and error process I discovered various grades of sweet-spot to be had, each trading a little of this for a gain in that; bass for more space, focus for scale, timing for impact and so on. And I started to enjoy the process. Despite the R 907’s bachelor pad pretences, this is a truly ‘tweaky’ enthusiast speaker with far greater potential for tuning than most traditional loudspeakers.

SWEET AND LOW
When the R 907s finally came to rest in my room they sat at the sweet-spot for popular beat combos, rock anthems and bombastic classical symphonies. The reason being that few, if any, sub-£10k speakers I’ve heard in this room deliver anything like the R 907’s super-low frequency punch and attack. Those twin drivers, free of cabinet colourations and back-pressure damping, offer remarkable output down to subterranean levels with bass speed and precision that makes many cabinet speakers sound merely pedestrian. If more loudspeakers delivered LF this low and this tight, subwoofers would be a thing of the past.
   The title track to The Raconteurs’ Broken Boy Soldiers is not so much played by the R 907’s as unleashed. The opening beat powers into the room and near physically makes your head bob in tune. As the howling guitars cut-in the soundstage swells to a Wembley-Arena sized scale. The step-down key change half way through the track is delivered with the sort of energy that could make the Pope pick up an air guitar.
   Meanwhile, the top-end cymbals crash out of those uber-efficient DTT HF drivers with equally robust and energetic stance giving the whole presentation an up-front and really lively balance. If your music collection starts and stops at
Brit-rock then you need look no further than the R 907s.
   The wonderfully box-free sound requires quite a romp through your CD collection to really get a handle on. It is so open and, at times, amazingly natural and unforced. Female vocal is a revelation in its simple cleanliness, particularly with my favourite bedtime audio tipple, Emiliana Torrini’s ‘Fisherman’s Wife’. The Jamos manage to avoid the chesty edge that her voice can acquire to varying degrees with most box speakers, letting her breathy tones wash over you in gloriously detailed waves.

WATCH THIS SPACE
What lets the R 907s down as an all-rounder is an in-room frequency response that I suspect looks like the Himalayas in profile. Many of the anomalies will be room and position dependent but no matter where I placed the speakers the mid-bass was light and recessed and the top end remained forward and peaky. Some shifting of position, particularly nearer wall placement, brought up the mid-bass but sacrificed the class-leading attack of the deep stuff.
   ‘Sister Sadie’ from the Ray Brown Trio’s Best Of... box set is a furiously fingered masterpiece of double-bass but much of the texture and warmth of the main instrument is lost to the Jamo’s mid-bass reticence. Again there is no shortage of pace and foot-tapping musicality to deliver that first-listen hit of euphoria, but the searing snare soon stifles the more delicate bass nuances.
   I can’t help but think this is a speaker that desperately needs space. I suspect a 5x7m-plus open-plan warehouse living space would allow the mid bass to breathe better and tame the top end with greater distance to the listening position. And you can’t knock a speaker for playing to a specific audience.

VERDICT
The R 907 offers spectacularly good deep bass and amazing midrange spaciousness offset by a lightweight mid/upper bass and a tweeter with a little too much energy for its own good. Lucid and utterly transparent at best while aggressive at worse, the design is incredibly room size and room position dependent. Still, it’s good value and offers plenty of tweaking potential for the strong of constitution.

Originally published in the October 2009 issue