ProAc K1 stand-mount loudspeaker
- Chris Thomas
- Jun 2021
I have never heard a bad ProAc speaker, and over the years, I have enjoyed them in many systems in many listening rooms. The K1 is the smallest of the K range, where the prefix refers to the Kevlar bass/mid drivers found in all models. The relatively recent K1 is the only stand-mount and follows a classic and traditional design model, proving itself over the years. The final success of the design always comes down to the implementation of the elements. Cabinet, drivers, crossover and stand, in equal order of importance. Get it right, and you can have a giant killer on your hands. I have heard so many systems that included various three or even four-way floorstanders that, in my opinion, would have been far more enjoyable if a high-quality two-way stand-mount replaced them. It seems that the promise of copious amounts of bass is just too hard to resist because a manufacturer told me recently that their market research informs them that floorstanders are what the audio buying public want.
But let’s start with what supports the K1 by looking at the high-mass stands themselves because one should never underestimate their, ahem, massive influence on what you hear from the finished installation. These come in a modular form and require assembly. A ringing bass plate with spike options and a more solid piece of steel beneath the speakers are separated by three wide diameter black tubular legs, with the possibility of filling them with sand. A solid aluminium post at the front of the speaker looks good and continues the design theme of the built-in plinth. These stands are an optional extra but, looking around, you’ll be lucky to find such a convenient fit elsewhere because the K1 is quite deep. Assembling them with a mixture of bolts is straightforward, and the black large-section supports tend to fade into the background because the bright, silvery front pillar takes the eye. Overall, they do the job, but I can’t help but think that they could have been more elegant and perhaps more minimal. Also, both the review speakers rocked very, very slightly on the flat top plate, so you need four tiny bits of Blu-tac to take up that slack. The spike fittings are up to the job, but I had the most success with a quartet of Stillpoints between wooden floor and base, and if I owned a pair of these loudspeakers, I might even think about damping the bottom with some stick-on pads.
The speakers themselves are immaculate, though the base might be better in a less ‘naked’ form. The review models were finished in Tamo Ash, a beautiful and highly figured light coloured wood, not unlike curly maple, with impeccably matched veneers. The cabinets themselves are formed from panels of HDF (high-density fibreboard), Bitumen-damped internally and of varying thicknesses. The first thing you will notice is the unusual built-in plinth which curves through an elegant arc at the rear of the cabinet to a 50mm space that is propped at the front by the same aluminium post material that fronts the stand. Visually it joins the stand to the cabinet, and that continuity is lovely and further detracts from the three bigger and uglier rear supports, as I mentioned earlier. Far from being just an aesthetic element, though, this is one of the K1’s main technical design features because the loading for the bass unit exits here in the shape of a hidden port. It seems to me that designer Stewart Tyler has been clever here in firing it downwards and fixing a boundary distance within the port’s influence. This port makes the K1’s behaviour more predictable and should give the user more latitude when finding their final listening positions. With a fair-sized cabinet such as this and a powerful Kevlar bass/mid driver crossing over at just above 3 kHz, I can see that a rear-facing port, though far easier to implement, could prove troublesome if you need to site the speakers close to a rear wall. In this configuration, it works superbly, and I couldn’t hear the port at all.
In a hotly contested market area, the K1 brings some serious driver armament to the table. A Kevlar 165mm (6.5 inch) bass/mid driver and a ProAc ribbon tweeter with an Alnico magnet that sits in its enclosure and features a diaphragm “As light as a human hair”, according to the literature, which is truly remarkable when you hear how it performs. A few years ago, Kevlar-coned drivers gained a reputation for harshness, but I could detect none after some bedding-in. We have a very, very stiff cone that is exceptionally responsive, can start and stop with impressive control, and is also nicely accurate pitch-wise and, when in the company of this admirable tweeter, very textural too. The midband is a real stand-out on the K1, as I’ll discuss later.
At around a healthy 90dB efficiency and with a benign 8ohm nominal impedance, I doubt you’ll have much trouble in finding an amplifier that will drive the K1. My advice would be to push the boat out in this department because the speaker will reward quality. The recently reviewed and very cost-effective Moonriver integrated amplifier springs to mind as a vice-free, well-priced option, but I spent most of my time listening to it with my trusty Vitus SIA-025. With this in place and operating in pure Class A, it took about a week of constant use from new before I thought the speaker came together musically. For this reason, I would always prefer to review a well run-in pair of speakers every time. When I first installed the K1, they were tonally cool, detailed, sharp and overly tight, but the ribbon and the bass/mid drivers were on no more than informal nodding terms. As the days passed, that 165mm unit loosened up, and they advanced toward a full handshake. It’s always fascinating to hear the noticeable ways that speakers develop with use, as with a week to ten days of intense exercise. The K1 became more musically whole and tonally expansive. The drivers, crossover and cabinet had formed a musical partnership, and I began to experiment with positioning.
They are actually quite forgiving in this respect and I had decent results near a rear wall but better with them standing in more free air which I certainly preferred. As ever, toe-in needs a bit of experimentation, never easy with a heavy stand-mount. Perhaps the reputation that ribbon drivers have with regard to high-frequency vertical beaming needs factoring in but these ribbons don’t strike me as being particularly guilty in this respect. If you want a clean-cut and fully detailed musical picture, you’ll likely end up with them directly facing the hot spot, but I eased that a little with a small toe-in angle without any significant drop off at high frequencies but I liked the driver integration and slightly relaxed presentation more.
It’s a fairly straightforward design, classic even, but there’s something so musically focussed about a properly designed two-way stand-mount with high quality drivers and a great crossover. It’s the sense of uncomplicated articulation coupled with a very focussed, free and dynamic bass that sits at the heart of great two-way designs, and the K1 is a superb example of that philosophy, with such a taut and stiff cone material as Kevlar, a synthetic Aramid fibre, the K1 drives with a real sense of purpose and most importantly, control. It is very fast with considerable transient power and the ability to translate what is happening in the bottom end with rhythmic flow and movement that grew more and more impressive as the hours and days passed. If you want to delve into what a bass player is doing, then the K1 will tell you in detail. Fast or slow, attack or decay, start or stop, it’s right there, on the button every time. But don’t ignore the influence of the ribbon in translating the music down here, either. That crossover is immaculately matched to the control of the drivers and the cabinet, and the speaker never wanders into vague territory. Dreaming Spirits from Mark Egan and Arjun Bruggman [Wavetone] features that singing fretless bass carries distant memories of the great Jaco and certainly has the whiff of Weather Report within its harmonic progressions cascading rhythmic signatures. This is a spacey, moody album full of soundscapes that speed and dart around the room, invoking a sense of floating mystery. The K1 was extra special here. That tweeter and its subtleties of tonal shading, control and texture really bring the music into the room. It is never wispy or remotely brittle, and I mean never. The bass/mid unit just sings, and the integration with the ribbon projects the music outside the speaker boundaries. In a word, it is seamless, and I used this album as a gauge for the K1’s run-in status over several weeks and as things improved tonally, so did the balance between technical precision of the speaker and the humanity of the musicians. It is easy to listen to the melody and the unique character of that fretless bass at any level. It’s picture painting in sound, and the K1 just glides through it with ease and great delicacy.
Every time I sat for a listening session with this ProAc, I was struck by its clean-edged directness and the neat, compact shape of the music. Suppose you like low-frequency bandwidth and love to feel that initial and compressive impact of a bass drum, then you won’t be disappointed. The sheer weight and punch is dramatic and, most importantly, clean. I ran through a few Billy Cobham albums, and it was good to hear his agility at the bottom of the kit potently expressed. Zero cabinet effects are dragging the tempo down. The interplay between Billy and his numerous bass players over the years was great because that strict sense of taut, bang, bang, bang pistonic drive that comparatively few speakers manage is easy work for the K1.
The K1 has all the good things that a properly designed two-way stand-mount speaker should excel in. Intimacy, speed, transient attack and recovery alongside eloquence are significant assets. But the K1 goes those extra steps along the musical path by having a quiet cabinet and a tonal palette that opens up the more beautiful aspects of music. Mainly through that lovely midband that, as the days passed, grew and grew in warmth and focus. I found myself reaching for piano music more often than usual. Labyrinth by Khatia Bhuniatishvilli [Sony Classical] has been stirring my contemplative side for a few weeks now. It’s a lovely recording for sure, but her sense of timing has a poignancy and considered pace that draws you toward the beautiful phrasing and her touch sensitivity on the keys, which itself is epic. It’s at times like this that this ProAc proved its inherent musical nature to me with its delicacy and, of course, the restrained power of the piano under her artistic control. Late night music, at its best for when the air is still.
A very accomplished and beautifully balanced design, the K1 deserves consideration in a hotly-contested market. Ensure that the demo pair you audition are fully run-in and nicely loosened because when they are, they sit confidently on the musical groove and just let it happen because this is always the message that makes the most persuasive case.
- Type: Two-way stand mount loudspeaker
- Drivers: 1 × 165mm Kevlar bass/mid driver, 1 × ProAc ribbon tweeter
- Sensitivity: 90dB
- Frequency Response: 28Hz–30 kHz
- Crossover: Dual-layer with oxygen-free copper cable split for bi-wired option
- Recommended Amplifier Power: 10–150 W
- Size: 569 × 210 × 401mm (H×W×D)
- Weight: 16kg each (35.5lb)
- Stands: Optional – 50 cm high
- Finishes available: Black Ash, Mahogany, Cherry, Walnut, Oak and Silk White
Rosewood, Ebony, Tamo Ash and dark Eucalyptus at extra cost)
- Price: £5,995 in standard colours
- Stands: £995
ProAc homepage – https://www.proac-loudspeakers.com/nfindex.php
K1 loudspeaker – https://www.proac-loudspeakers.com/html_files/Speakers.php?Range=K&Speaker=K1
UK Dealers – https://www.proac-loudspeakers.com/html_files/Dealers.php
Worldwide distributors – https://www.proac-loudspeakers.com/html_files/Distributers.php
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