Monitor Audio R352s are veneered in walnut and look very nice. A close inspection showed no flaws and the only possible criticism was a rather rough edge to the reflex port; as this is normally concealed behind the neat framed black grille cloth, it is a minor point. An 18mm particle board, veneered on both faces to avoid warp, is used for the cabinet, with a thinner material chosen for the black painted baffle. The rear face is finished with a brown speckle paint and has a recessed panel (actually the reverse side of the crossover board) carrying the adequate 4 mm socket/terminals. Internally there are two braces fitted to the long sides and all surfaces are covered with 25mm plastics foam absorbent. Two drive units are used in the R352. High frequencies are handled by a SEAS 20mm plastics dome tweeter recessed into its front plate, which is in turn recessed flush with the baffle near to the upper edge. Bass and mid-range are handled by a centrally placed 200mm paper cone unit made to Monitor Audio's own design. This has a 25mm voice-coil moving in a gap claimed to be near saturation flux from the powerful magnet. The frame is a steel pressing again recessed flush into the baffle. The paper cone chosen is notably thin, completely free of additional damping and of almost flat profile; there is the usual PVC surround and central dust cap. The free air resonance is set at about 42Hz and the band-pass resonances in the reflex cabinet with its 65mm port and 40mm tunnel occur at 25 and 78Hz. As the cabinet is large and there is little damping anywhere, these resonances are both quite marked.
Listening tests rapidly established that the R352 boasts much above average sensitivity, a direct result of the lightweight cone and large cabinet. Nevertheless the clear mid-range quality satisfactorily confirmed that cone break-up, normally the big risk factor in this design approach, had been kept at bay. There is a slight hardness to the treble, perhaps because the units overlap considerably (but with different directional characteristics) and rather surprisingly the tweeter seemed to fade at the highest frequencies, taking away a little life from the transients. However these minor problems were not sufficient to damage the stereo image which held remarkably well over a wide selection of programme material, helped immeasureably by that smooth open mid-range. I was not so happy when considering the lower frequency end of things. There are obvious colourations in the area below 250Hz, which some reviewers have called warmth but are neither pleasant nor natural to my ears and certainly spoil the realism of male speech. Going lower still, there is a hump apparent around the area of the upper band-pass resonance which may well be popular with rock music enthusiasts; sadly a serious falling away occurs below this, giving emaciated results on organ pedals, bass drum and even tymps, which sounded more like someone kicking a large cardboard box. Investigating these deficiencies soon established that most of the colourations were produced by amounts of unabsorbed audio waffle barrelling around in the cabinet and falling unchecked out of the port. An ear placed against the latter was immediately assailed by this resonant drumming, which makes such an unwelcome addition to the overall sound. Recourse was therefore made to my collection of corks, stoppers and bungs and the offending holes sealed off. Not only did this largely remove this aural detritus (a mite still penetrates through the thin cone) but it also lowered and flattened the bass hump—the single resonance now appearing at 65Hz—greatly improving the character and weight of real bass artifacts. So where is the catch? A loudspeaker unit required to work in a sealed enclosure, even a largish one, really wants a more substantial cone to resist the pressures it must overcome or it will flex and distort; this would reduce sensitivity (and we have already thrown away the contribution from the port on other grounds). Furthermore the unit may not be able to achieve the displacement required to move sufficient air at low frequencies or, if it can, it will certainly not remain linear over its extended travels—distortion again. Yet surely the ear must be the final arbiter and, if my main interests required the accurate, real world reproduction of music rather than a coloured impressionistic view, and they do, then this is how I would use them. Particularly as I would not seek to drive this loudspeaker to anywhere near its maximum level and therefore any resulting distortion would be lessened.