PMC Twenty.26 floorstanding loudspeakers

PMC Twenty.26
PMC Twenty.26 floorstanding loudspeakers

PMC’s Twenty.26 is the fifth and latest stereo pair in PMC’s mid-price Twenty series, and appears to have a concept and numerous elements in common with the much more costly fact.12. However, many of those commonalities are in truth illusory; the only component the two models actually have in common turns out to be just the stainless steel spikes – even their associated locknuts are different!

That said, both are slimline three-way floorstanding designs, both use PMC’s trademark ‘advanced transmission line’ (ATL) bass loading technique, and both feature 50mm diameter midrange drive units. These midrange dome drive units are both based on some very interesting research carried out at the National Physical Laboratory, by PMC’s Oliver Thomas, alongside its resident physicists (see page 16). A radical non-intrusive laser-based method was used to optimise the shape of diaphragm and faceplate for the smoothest pattern of sound distribution. The difference between the two versions is that the fact.12’s version is made in-house by PMC, while the later version developed for the Twenty.26 has been re-engineered for less costly manufacture and is made by an outside supplier. Otherwise, it’s pointless trying to list all the differences between the two models.

The Twenty series currently consists of five stereo pairs – two standmounts and three floorstanders – plus centre-front ‘dialogue’ and subwoofer speakers for AV surround sound users. As previously stated, the range-topping Twenty.26 is a three-way design. Its bass unit is a 170mm cast alloy frame and a 125mm diameter doped paper cone with an unusually large (c90mm) dust cover. The 50mm dome-shaped midrange unit and 27mm tweeter both have soft fabric domes that are inherently rugged, even though both are also protected by perforated metal grilles.

Perhaps the most obvious distinction between all the stereo Twenty series models and the overwhelming majority of the competition is that they lean ‘backwards’ a few (actually only five) degrees. This is not only rather stylish, but also means that the voice coils of the three drive units approximate a vertical line more closely than would be the case if the drivers were mounted on a vertical baffle. This might well help simplify the crossover networks, which inevitably tend to be complex in a three-way design such as this, especially since PMC has always favoured steep (4th order) filtering. Indeed, the fact that the electrical and acoustic crossover points (measured at 500Hz for both and 4/3.5kHz respectively) are so similar is an indicator of the steep filtering, evidenced by the crossover points at 380Hz and 3.8kHz.

To stop the backward tilting enclosures from falling over – and also to ensure a solid foundation for the floor spikes – a hefty black-painted Medite/MDF plinth is supplied, with the rearward extension required to handle the tilt. This is bolted securely to the base of the speaker, albeit not so tightly as to crush the cork washers that add a measure of decoupling. The shiny stainless steel spikes come complete with matching lock nuts that may be tightly fastened.

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