PMC twenty5.21

Hardware Review

PMC twenty5.21
Monday, January 29, 2018
standmount loudspeaker
Jason Kennedy

I had a lot of fun with the last .21 model from PMC, the twenty.21 is small and energetic with a lot of charm, a genuine pocket rocket of a speaker that makes up for its limited bass extension with superb timing and musicality. So when the twenty5.21 turned up I was expecting the same but more, what I got turned out to be more but in a very different way. The two speakers may share much the same cabinet and drivers of the same sizes but the similarities end there, the more expensive twenty5 series model is a far more sophisticated and revealing loudspeaker, so it doesn’t grab you straight away but gradually gets under your skin and makes itself an essential part of listening enjoyment.

 

 

The twenty5.21 has many similarities to the twenty5.23 floorstander but comes in a smaller box, so the drive units are the same but the space available for the tapered and damped transmission line is considerably shorter. Which equates to bass that doesn’t extend so far and in all likelihood less dynamic capability. Yet neither of these things stand out in the listening because it delivers such incredible coherence and large scale imaging. The twenty5 series were developed with the aim of getting higher potential output level and lower distortion than the twenty models whose shape they emulate. The first element that was worked on was the mid/bass driver where designer Ollie Thomas chose a woven material for the cone so that it could cope with the power and long throw that he wanted. This increased cone movement created a problem however, the speed of air leaving the end of the line was causing turbulence as it left the vent and this muddied the sound of the bass, an area where PMCs have always been particularly strong.

In order to combat this Ollie drew on his experience in F1 car development where methods for dealing with turbulence have been refined for decades. This lead to fins or strakes being used in the vent that allow for faster and smoother air movement. It’s a clever idea that contributes quite significantly to the advantages of the twenty5 series models and one that I have been badgering PMC to incorporate into the fact series models, one of which I use as a reviewing reference. The treble driver is a 27mm soft dome that PMC developed with SEAS and is found in a number of models because it obviously suits their needs. It sits behind a dispersion grille that also has the benefit of protecting the dome from the curious, the grille for the speaker is a magnetically attached type.

 

 

The twenty5.21 stands 34cm (13 3/8 inches) high and has a sloping cabinet designed to create a degree of time alignment between driver centres and, naturally, to look cool. Internally it’s divided up to create a transmission line that’s over five and a half feet long, this is damped with carefully selected foams in order that only the lowest frequencies produced by the back of the main driver make it to the vent. The crossover is fixed to a stainless steel back plate chosen so that the components characteristics do not change with variations in power, it also looks great. There is only one pair of cable terminals but they are custom made with matte rhodium plating and knurled ends. As the sensitivity of the twenty5.21 is only 86.5dB it is wise to connect up an amplifier with reasonable power reserves, but it doesn’t need to be a brute. PMC’s own Cor integrated is rated at 95 Watts, but I wouldn’t expect much joy with a single ended triode design.

Sound quality
I used an ATC P2 power amplifier which is more powerful than most and proved a good match, its calm grip allowing the twenty5.21 to deliver an effortlessly detailed and surprisingly wide bandwidth sound for such a compact box. With Trentmoller’s refined electronica it delivered a cosmic result and it just kept getting better with every piece of music I played, including the perfect groove of the Grateful Dead’s ‘Roll Away the Dew’ (Blues for Allah) which compelled me to turn it up and enjoy the full effect. This revealed that the size of this speaker does indeed limit its dynamics and that it does not break the laws of physics, which is probably for the best. What it does do is have vanishingly quiet backgrounds, there is clearly very little being added by the box and drivers because you can hear such quiet sounds. A speaker is a passive device and thus doesn’t have a noise floor in the usual sense but a speaker that doesn’t vibrate or ring after each note is effectively quieter than one that does colour the result with its own resonances. A violin’s sound is a result of strings vibrating wood, a speaker’s sound is dictated to a large extent by the drive units vibrating the cabinet (which is why non wooden speakers sound so different). It would be better if the cabinet didn’t vibrate at all and a small well braced cabinet like this one has a natural advantage in this respect.

 

 

It accounts for why you can hear so much of each recording and for that matter each piece of equipment. Therefore the better the source the better the result, so playing Anouar Brahem’s Blue Maquams album on the CAD 1543 MkII DAC through these PMCs made for very compelling listening. This musician’s oud playing is subtle, it’s rather like Bill Evans’ piano playing, you have to pay attention and it takes a good speaker to let you hear the subtleties and make the music involving. The twenty5.21 is singularly excellent at this. It is also rather good with intense and powerful music where it’s ability to separate the various instruments and voices means that the music remains intelligible at virtually all time. The other key quality is its timing which is absolutely impeccable, you can have all the detail and openness in the world but if you can’t hear the timing, the interplay that great musicians are so good at then you end up with an uninspiring result. That is definitely not the case here, you can throw any kind of music at all at this speaker and it will let you know all about it. I guess that those after Cradle of Filth in full effect would be better off with a larger loudspeaker, but the power handling capability of this PMC far exceeds expectations and it’s really only in the lower octaves that you sometimes feel the need for more. I found that by placing them close to the wall (30cm/1 foot) they delivered remarkable extension for their size.

Every loudspeaker is at the mercy of the source of the signal but not all of them let you hear so much of a source’s potential as the twenty5.21, as much became apparent when the ground breaking Innuos Zenith SE network server arrived. The extent to which this upped the ante was very clear indeed, both server and speaker have very, very low noise so the combination lets you hear so much fine detail that it can be jaw dropping. I particularly enjoyed Bert Jansch’s Jack Orion where the speed and transparency of the speaker allowed all the intensity of his acoustic guitar playing to come through in dramatic effect. It’s not the sweetest sounding of recordings but let’s you know just why Jimmy Page in particular took so much from this underrated musician. If you want to hear an acoustic guitar properly thrapped look no further than the title track.

 

 

Not many companies with as many models as PMC build a luxury stand mount, it’s usually the domain of boutique brands, but this means that they can invest such products with technological and cost advantages that no small scale company can match. Which is why the PMC twenty5.21 is such a revealing and even handed loudspeaker, its own characteristics are so subtle that only comparison with something much more expensive would reveal them. In other words it’s very hard to fault and never draws attention to itself, rather it acts as a conduit to the beauty and drama of the music it plays and if it’s emotional communication that you appreciate then this is a very hard act to beat at any level.

Specifications: 

Available Finishes: Walnut, Amarone, Diamond Black, Oak
Crossover Frequency: 1.8kHz
Drive Units:
LF - PMC twenty5 series 5.5”/140mm long-throw g-weave cone with cast alloy chassis
HF - PMC/SEAS, 27mm twenty5 series, SONOLEX fabric soft dome, Ferrofluid cooled
Effective ATL™ Length: 1.72m 5.6ft
Frequency response: 46Hz – 25kHz
Impedance: 8 Ohms
Input connectors: One pair 4mm binding posts
Sensitivity: 86.5dB 1W 1m
Dimensions: H 340mm x W 162mm x D 284mm (+9mm grille)
Weight: 6kg

Price: 
£1,950
Manufacturer Details: 

The Professional Monitor Company Limited
T: +44 (0)870 4441044
pmc-speakers.com