It's less than five years since we first encountered MonoPulse, as a relatively new brand with a number of interesting and unconventional ideas about loudspeaker design. Patron and hi-fi enthusiast Allan Hendry, worked for many years on pulsed, phased-array radar and after his retirement, applied his appreciation of the importance of phase relationships to loudspeaker design. These applied especially to the relative positioning of the drive units and their integration through the crossover network, in order to achieve genuine wavefront time-alignment through the entire region.
We actually reviewed the original version of the 42A back in 2005, when it was the top model in the range and priced at £995 a pair. Now it returns, similar in outline but somewhat different in detail, and carrying an altogether heftier £1,495 pricetag (£1,595 with external damping bar as tested).
The styling is very original and striking, with a wide steel wrap in the shape of a tall inverted-U forming the sides and top and firmly bolted onto the outside of a fabric-covered wood-composite enclosure.
This is also wide enough to accommodate the relatively large diameter 218mm Audax paper-cone bass/mid driver, while a reflex port is fitted into the base of the enclosure, firing downwards and held about 4-5 cm off the floor by some purposeful and well-seated spikes. The enclosure is roughly the same depth as its width, so the footprint is quite modest, but the hefty 28kg weight guarantees good physical stability.
As part of the time alignment, the two drivers are mounted on separate baffles, so the bass/mid driver fixing is slightly nearer listeners than the Morel-sourced 28mm soft dome tweeter. This also provides some mechanical and acoustic isolation between the drivers.
Although our samples came in a sober combination of metallic gunmetal and slate, the steel wrap and the two separate grille cloths are also available in a variety of colours. The lower part of the front panel was fitted with an offset metal damping strip that adds £100 to the price. Signal connection is made via twin terminal pairs, allowing for adventures in bi-wiring or bi-amping.
The 42A requires free space siting to deliver the best bass alignment, with the time-aligned crossover and precise drive unit spacing responsible for the remarkably impressive coherence, especially through the voice band, which seems to be MonoPulse's particular stock in trade. This in turn helps to sharpen the image focus and precision, more accurately and convincingly defining the position of a performer in space.
That's by no means the 42A's only strength. The large main driver helps deliver fine performance through the bass and midband, with good overall balance and ultimate bass extension. Best of all is dynamic expression, which is comfortably ahead of the pack and further enhanced by the superior timing and across-the-band time coherence.
The down side, is a degree of boxy coloration. While some listeners may find this unpleasant, others might well see it as an acceptable trade-off for the tight time coherence.
The original 42A was criticised for a rather too restrained top end and that is one factor that has received attention here. The top end is certainly better balanced, possibly as result of the change in tweeter, but it's still lacks some sweetness when compared with its rivals.