PMC has built its brand on a cabinet loading technology that had all but disappeared when the company was launched in 1991. The transmission line became the advanced transmission line or ATL in Pete Thomas and his late partner Adrian Loader’s hands. The advanced refers to the use of damping foam in the line that runs from the back of the main driver to a vent at the bottom of the box, the material being selected so that only the lowest frequencies escape from the vent and the length of the line chosen so that what comes out is in phase (time) with the output of the main driver. PMC has further advanced this loading system by adding fins to the vent that prevent turbulence and allow for a smooth flow of air, further clarifying the sound of the system. This system is called Laminair and first appeared on the twenty5 series when it was launched in 2017, so it’s perhaps surprising that the company has upgraded this range to twenty5i status so soon. But the PMC R&D department, headed up by Pete’s son Oliver, doesn’t rest on its laurels and in the intervening three years it cooked up the biggest PMC yet seen in the Fact Fenestria. This is one of those products that’s so expensive that few of us will ever get to hear it in anger but was used as a means of researching new technologies to trickle down into real world speakers. The twenty5i range is the first place the trickle has made an impression.
It has impacted the twenty5i models in two ways; the most obvious is in the tweeter which is very similar to the model created for the fact models and designed by PMC in collaboration with Norwegian driver specialist SEAS. This has a 19mm dome at the centre of a large roll surround that brings the overall radiating area up to 34mm. There is always a trade off with loudspeaker cones and domes, the larger they are the more power can be produced but the lower the usable bandwidth that can be delivered, eg. a 12 inch bass driver can generate serious sound pressure levels but doesn’t produce clean midrange let alone treble. In this tweeter the small central dome gives very high frequencies and wide dispersion while the extra area of the surround enables high power handling and a lower crossover point to the midrange.
The two floorstanders in the twenty5i range benefit from another aspect of Fenestria research, vibration control. Although the plinth bars on this model look much like those on the preceding twenty5 models there is a vital difference in the form of rubber grommets that provide a degree of isolation between cabinet and metal bar. These sit either side of the bar with a bolt through to the cabinet base, the rubber like material ensuring there is no metal to metal contact and the instructions urging users not to over tighten them, which reduces the amount of isolation provided. PMC are the only major brand to have used Townshend Seismic Podiums under speakers in demonstration and clearly understand the benefit of compliant isolation, but rather than use springs they looked for material that would provide the best sonic outcome with the minimum of impracticality. They discovered that by significantly reducing vibration transmission around the 400Hz point that the quality of midrange was greatly improved and found a compound that provided that isolation. PMC supplies custom machined stainless spikes to fit into the plinth bars and these can be used with or without receptors provided to protect wooden floors, so there is still a firm connection to the floor at lower frequencies.
The 6.5 inch bass driver in the twenty5.26i has a woven cone in a very minimal cast alloy basket, it’s a long throw type that’s designed to cope with high power outputs over extended periods. PMC’s experience in studios has taught them a lot about making bomb proof drivers. The midrange is a 50mm fabric dome and the only one you’ll see in this particular speaker range, what with the 26i being the biggest model and all. PMC also go to some lengths with the crossover which uses military grade fibre glass boards and thick pure copper tracks for its fourth order slopes. It connects directly to a single pair of high quality cable terminals in a matte finish stainless steel back panel. The whole speaker whether it be in real wood veneer or one of the two paint options available is exceptionally well finished and attractively appointed.
In the system with an admittedly rather affordable Rega Elex-R amplifier on the other end of the speaker cables these speakers made a positive impact with a tremendously open and rhythmically clear-cut presentation, the slightly dry character of the Rega was apparent but that did nothing to undermine weighty bass and excellent lyrical intelligibility. No matter how much Tom Waits muttered and grumbled I could tell what he was saying, it really brought out the pathos in the songs. I’m a big fan of Townshend isolation bases because they let the sound escape from speakers so well, the PMC isolation system seemed to have the same effect. PMCs tend to be more open than most because of the company’s emphasis on dispersion and the isolation system does nothing to undermine this, quite the opposite.
By using a fairly stiff isolation system at lower frequencies their system allows these speakers to deliver powerful, at times menacing bass whilst the midrange exposes all the fine details that create a sense of an instrument in space. This was made clear by playing Keith Jarrett’s Budapest Concert (ECM) where the quiet coughs of the audience appeared in the mix for the first time, I was almost surprised that Jarrett didn’t throw some of his toys out of the pram. On Bob Marley and the Wailer’s ‘Natural Mystic’ (Natural Mystic (The Legend Lives On) Island), which has become my ‘go to’ bass resolution track of late, the solidity of the low end is balanced by texture and depth to the notes. These PMCs are first rate at producing a three dimensional soundscape, putting the music and its reverberations and harmonics in the room with you.
Moving up to the considerably greater power of an ATC P2 amplifier with the Townshend Allegri+ preamplifier brought a strong sense of control to proceedings, if nothing else this amp has grip. It lets you hear a lot more in ‘Natural Mystic’ and brings a degree of immediacy and presence to the sound that is addictive. The result is vivid and precise but remarkably fluent with it, the sheer amount of inner detail that came off Yussef Kamaal’s superb ‘Remembrance’ (Black Focus, Brownswood Recordings) made the drums sound tremendously real, while the Rhodes keyboard’s higher notes had a shine and vibrance to them that felt so right. The midrange on this speaker is very special indeed but it wouldn’t be that way if the treble weren’t totally seamless and effortlessly extended, I noticed this with the twenty5.22i two-way and it remains so here. The bass is phenomenally clean and articulate and this explains both the quality of timing on offer and the overall musical ease of the speakers even at higher levels.
Switching to the Moor Amps Angel 6, an amplifier that has since become a mainstay of my system, and pairing it with the Allegri Reference preamp took the experience onto another plane, revealing qualities in recordings that had hitherto been very well hidden. The twenty5.26i laps up upgrades in source and amplification, making it clear that its transparency and neutrality are there to be exploited. This amplifier’s dynamic range makes most alternatives sound compressed; it’s not unduly powerful (150W/8 Ohms) yet it finds dynamic contrasts that can be positively shocking, such as the bass that comes out of Bugge Wesseltoft and Henrik Schwarz’s ‘See You Tomorrow’ (Duo, Jazzland), is a track I’ve played many times yet never really heard it seems. It’s remarkable what modern loudspeakers can find hiding on your favourite albums, the state of the art is clearly progressing at a healthy pace.
The twenty5.26i might be a tricky sell for PMC, not because of what it can do but because of the company’s mid price origins. This is a genuine high resolution loudspeaker of that there’s no doubt but I fear that the snobs among us might feel the brand is a little bit too well known for it to get the recognition it deserves. The transparency to both the source recording and the ancillary components that the twenty5.26i delivers is in a higher league than its price, don’t let the fact that PMC is a well established marque stop you from giving it a try, or you’ll miss a genuine musical and audiophile treat.
- Type: 3-way, three-driver, floorstanding speaker with PMC ATL (Advanced Transmission Line) enclosure and isolation base
- Driver complement: One 19mm SONOMEX soft dome, ferro-fluid cooled tweeter with 34mm surround; one 50mm soft dome, chambered soft dome mid‑range; one 6.5”/170mm long-throw g-weave cone with cast alloy chassis
- Crossover frequencies: 400Hz, 4kHz
- Frequency response: 27Hz–25kHz
- Impedance: 8 Ohms
- Sensitivity: 86dB/W/m
- Dimensions (H×W×D): 1040 × 192 × 439mm
- Weight: 25kg/each
- Finishes: Walnut, Diamond Black, Oak, White Silk
- Price: £8,995/pair
Tel: +44 (0)1767 686300