PMC twenty.sub - First Impressions

Does the Eclipse TD520SW have a rival for Ed Selley's affection?

by Ed Selley May 7, 2015 at 5:10 AM

  • Hi-Fi Article


    PMC twenty.sub - First Impressions
    When you are a speaker manufacturer renowned for making speakers with serious low end, the business of augmenting this with a subwoofer is no small undertaking.
    PMC as a brand is synonymous with the use of transmission line technology. This means that even their more compact offerings have substantial low end shove and their larger speakers have serious bottom end. As a result of this, PMC hasn't been in any great hurry to make more subwoofers but they have responded to requests to give the twenty and above ranges a little low end enhancement.

    The Subwoofer
    PMC twenty.sub

    The result of this demand is the twenty.sub subwoofer that broke cover in Bristol. As you might expect, the design wasn't an 'ordinary' one. The twenty.sub is built around a pair of 7 inch long throw drivers which are powered by a 400W Class D amplifier. While two 7-inch drivers gives a radiating area of roughly a 12 inch one, it is the use of a transmission line - in this case a whopping nine and half feet in length to give them the required heft. There's also a full suite of DSP functions, along with level control and settings, and slope and crossover points via a full control set on the rear panel.

    The impressions I gained of the sub at Bristol were positive. It was filling a large room without sounding strained and crucially for both fans of PMC and my own personal preferences, there were clear signs that the speed of the sub - the way it started and stopped and handled complex basslines and effects - was impressive.

    Ultimately though, while I have been to the Marriot Hotel in Bristol more times than I'd like, it is still not a room I am intimately familiar with. Regrettably, as there is only one twenty.sub in the world at the moment and it will presently have to make its way to Munich, it won't make it to my house for a while yet. Nevertheless, as a consolation, PMC organised a session for me to listen to the sub at their demo facility at Metropolis Studios in London. I could have a listen to material I was familiar with in a space that while rather better treated than a normal lounge, wasn't radically different in size. Afterwards I was taken for a quick look around the studio.

    PMC twenty.sub
    The first impression of the twenty.sub is that it is smaller than I thought it was going to be. At Bristol, in the centre of the display and lit by purple spotlights, the chassis looked to be very large indeed but up close and personal, the dimensions are actually very sensible. The PMC is a result of the demands made by the technology it uses so it was never going to be a conventional cube. The chassis is instead narrow and deep but PMC has used their comparatively recent understanding of the exciting concept of 'styling' to reduce the visible bulk by adding the same lean to the front and rear panels as the passive speakers have and to produce a very clean looking product overall.

    For the demonstration, the sub was joined by a pair of twenty.26 floorstanders for front left and right, a twenty.c centre speaker and a pair of the twenty.23 floorstanders at the rear. Electronics used were a Bryston SP3 processor, a wedge of accompanying Bryston Power amps and an Oppo BD105 Blu-ray into a JVC projector. If you are thinking this is all a bit overkill for a sub - even a sub that costs £2,950 you might be right but it does make for a challenge nonetheless. The sub can't make use of that excellent Bryston amplification so it has to be judged in combination with speakers that have excellent bass response in their own right being driven very well indeed.
    The first impression of the twenty.sub is that it is smaller than I thought it was going to be.
    And the good news is that by and large, it does that very well. Kicking off with PMC's own choice of the Total Recall remake, the scene at Rekall is handled with assurance and the twenty.sub gets a number of key attributes exactly right. The integration between the speakers and sub is excellent both in terms of the handover from passive to active and the tone of the bass itself. As suggested at Bristol, the PMC has the speed it needs to sound lively and agile and it manages to draw very little attention to itself.

    PMC twenty.sub

    Switching to the material I brought with me - copies of Unstoppable and Rush - the impressions are cemented by material I know better. PMC has not set out to produce a device that can liquify your internal organs. The claimed low end extension of 22Hz is probably attainable with only mild roll off but this is a sub that shares more in ethos with the enormous BB-5 pro monitor than an effects speaker. It is designed to add a perfectly integrated octave (or two depending on the partnering speakers) of low end to a speaker with more than reasonable bass as it stands and this is something it does incredibly well.

    This means that the attempts to slow down the runaway 777 in Unstoppable are captured with detail and exceptional pace. There is easy differentiation between the noise of the train proper and the impact into other things. Equally, Rush, with its heavy use of effects at the high 30Hz to 60Hz range which can be a nuisance for systems with poor integration is handled with equal ease and really shows how well PMC has cracked the handover between the passive and active sections.

    PMC twenty.sub

    Finishing off with some music in multichannel- in this case a spirited rendition of Superstition from the Stevie Wonder gig at the O2, the twenty.sub rams home how effective the use of smaller drivers is for a fast and effortlessly rhythmic sound. In a way, the PMC is preaching to the converted because as my recent eulogy to the almost identically priced Eclipse TD520SW showed, my personal preferences will always happily trade off a fraction of low end extension for proper speed, refinement and detail. If you feel differently, I don't think that the PMC is going to truly convince you otherwise. Nonetheless, there aren't many subs I've heard that can handle music so effectively.

    So, what do I take from the demo? The twenty.sub is distinctive and full of some unusual touches but offers the most effective partner I've heard to the twenty series speakers in terms of augmenting their distinctive and excellent bass response. It isn't cheap and it isn't an absolute monster but even in the heavily damped demo room, it suggested it has the effortlessness and power in reserve to produce excellent performance. Once series production is underway, I look forward to trying it in more familiar surroundings.

    The Studio
    PMC twenty.sub

    The choice of venue for the demonstration is not an accident. Metropolis is one of the leading independent studios in Europe and since it was founded in 1989 it has had a close working relationship with PMC who have equipped the various studios with their mighty pro monitors. The building is a modified power house for the old tram system - which although it was purpose built for, it actually only did for a comparatively short period of time. The owners and developers of Metropolis have done an excellent job of creating impressive and inert spaces in the building while keeping a lot of the industrial character.

    The highlight for me was meeting mastering engineering Tim Young a Grammy award-winning mastering engineer for Metropolis. Having worked on a list of albums that includes some standout classics (and, I only realised after I met him, my current favourite album, Public Service Broadcasting's The Race for Space), Tim has enormous experience of the foibles of the industry and the sort of understanding of the recorded arts that most of us would kill for.

    PMC twenty.sub

    The suite is set for editing in stereo and multichannel and a quick blat of the active BB5-XBD-A speakers was quite something. Each BB5 is comfortably taller than me. If it can be said that all design speaks something of the intent of the designer, this has the same swagger as the bloke that knows they are the toughest and most capable person in the room and has no need to show off. This means that they will of course go devastatingly loud but they have the same peerless integration and fine detail retrieval that PMC is striving to recreate with the twenty.sub.

    PMC twenty.sub

    Elsewhere, I was shown the facility where Metropolis can record direct to vinyl acetate. The machine itself is pure heavy engineering of the type I lamented the passing of in the recent podcast and only its enormous weight prevented me from trying to make a run for it with it in tow. Metropolis is of course happy to work exclusively in the digital domain (and Tim demonstrated how simple advances in processing power actually have an effect on the sound of a recording) but this room and the amazing reel-to-reel machines scattered around the facility make it clear that if you want to do it the old fashioned way, they've got you covered.

    More importantly, it reminds you that PMC's pro heritage is not something from the dim and distant past or talked up to sell more domestic products but a very real part of the company's business that shapes all aspects of their design practise.
    My experience with pro audio is relatively limited and I always find the enormous mixing desks to be a source of fascination but there is no question there are some mighty fine sounding rooms here. This, of course, isn't an accident. Most of the studios use room within a room principles for isolation and effective room treatment is carefully but sensitively applied. The result is that even in fairly small spaces, speakers are beautifully dialled in to their surroundings and they are an eloquent demonstration of how much influence the room has on the overall sound of the speakers.

    More importantly, it reminds you that PMC's pro heritage is not something from the dim and distant past or talked up to sell more domestic products but a very real part of the company's business that shapes all aspects of their design practise. In the case of the twenty.sub, this has resulted in a unique but extremely capable product that should provide an interesting alternative option at the £3K price point.

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