GIK SlatFusors

The SlatFusors are available in several depths to suit different environments.

GIK’s ingenious new design provides both absorption and diffusion, at a highly affordable price.

Manufacturers of acoustic products aren’t just competing with each other: they also need to offer something we can’t easily build ourselves. When it’s so cheap to pop down to your local builder’s merchants and pick up a few slabs of Rockwool, commercial makers need to differentiate their products from simple DIY options. They can do this by offering better performance, smarter appearance, greater convenience or a design that can’t easily be home‑made. And with their new SlatFusor line, GIK seem to have achieved all four things.

Absorption & Diffusion

In general, acoustic treatment employs two basic mechanisms: absorption and diffusion. For a typical small studio, absorption is the more relevant. Small spaces have inherent low‑frequency issues relating to the room modes, and the best way to tackle these is to absorb or ‘trap’ the bass energy that would otherwise excite standing waves in the room. This can be done in several ways. Basic panels and corner traps are usually little more than a block of mineral wool in a covered frame. These are easy to DIY and can be effective over a wide frequency range, but in order to achieve much at low frequencies, you’ll need a lot of them. An alternative is to use tuned devices such as Helmholtz resonators or limp‑mass membrane absorbers. These provide more space‑effective absorption that is targeted at specific problem frequencies, but they are not trivial to DIY.

Diffusion, or scattering, tackles a different acoustic problem. When we put in enough absorption to properly control the low frequencies, it’s very easy to over‑damp the midrange and treble, leading to a room that sounds muffled and dull. It’s important to retain hard surfaces to reflect the right amount of midrange and high‑frequency energy back into the room. However, flat walls tend to produce a few discrete echoes, when what we want is a more diffuse reverberation made up of many small reflections. Diffusors can help to break up and scatter the reflections and deliver the kind of benign reverberation we’re after. There are many different designs, but what all of them have in common is that apparently trivial details tend to be crucial to their effectiveness. What looks like a random arrangement of dowels, holes or slats is actually a mathematically generated structure that needs to be built exactly to specifications in order to have the correct properties. So, although it’s possible to create DIY diffusors, it isn’t easy.

If you’re creating a studio space from scratch, one popular approach is to build the absorption into the walls, which can then be faced with a porous diffuser of some sort, so that the wall itself acts both as an absorber and a diffusor. But if you’re converting an existing room, the absorbers have to be inside the room, so the more absorbers you have, the less wall space remains for diffusors or other reflective surfaces. Unless, that is, you use GIK’s SlatFusors.

For the loss of a few inches’ depth, ordinary walls gain two useful acoustic properties when SlatFusors are hung on them.

Slat Happy

The basic idea behind the SlatFusor design is clever and conceptually simple, but probably not easy or cost‑effective for most of us to DIY. In essence, it’s an absorbent panel fitted with a front face that is both an effective diffusor and, to some extent, a membrane absorber. Different sizes and depths are available, and whereas basic absorbers tend to work best when spaced away from the wall, GIK say their tests show the SlatFusors are most effective when placed directly on the wall. So, for the loss of a few inches in depth, ordinary walls gain two useful acoustic properties when SlatFusors are hung on them.

The SlatFusors are available in four different depths — 25, 50, 100 or 150mmone, two, four or six inches — and as square 600mm23.5‑inch or rectangular 600 x 1200mm23.5 x 45.5‑inch panels. I went for the 150mmsix‑inch version of the latter. Note that the nominal depth refers only to the absorptive panel: the diffuser adds another 30mman inch or so in front.

SlatFusors are manufactured to order and delivered by a standard courier service. The entire process is impressively fast. The build quality of the review SlatFusors was impeccable, and certainly far better than I could have achieved with my limited DIY skills. The wooden frames housing the absorption are rigid and precisely constructed, and neatly faced with black fabric that is held in place using staples. The diffusion on the front panel is effected by slats spaced at regular intervals along a flexible baffle made of high‑density felt. This material is carefully chosen so as to not only allow sound energy to penetrate to the absorptive material inside, but also to provide an element of limp‑membrane absorption.

The slats themselves are backed by a sheet of high‑density felt which provides some resonant absorption.

If you order multiple SlatFusors, the necessary fittings are supplied all together in one of the boxes, along with a generic instruction manual that covers installation of all GIK products. Several different hanging and mounting systems are used for the various panels in the range. In the USA, the SlatFusors come with ‘sawtooth’ hangers, whereas units sold in the UK and Europe are supplied with ‘French cleats’. These are a neat and unobtrusive way of mounting panels on a solid wall: basically, you get two bent pieces of metal, one of which is attached to the wall and the other, inverted, to the rear of the panel at the top. The cleat on the panel then simply drops into the wall‑mounted bracket and a combination of gravity and friction keeps your panel securely in place. There’s scope for adjusting the left‑right position of the panel after installation, but you need to make sure you get the vertical alignment right first time.

You need to attach cleats to panels yourself, which involves drilling into the frame, and could perhaps benefit from slightly more detailed instructions. The cleats each have four holes, but only two screws are supplied or needed. I found in a couple of cases that holes were blocked by the staples used to attach the fabric, so it was useful to have the options. Note that if you plan to mount several SlatFusors together, it’s important to attach the cleats to the same end of each of them — the back is symmetrical, but the front isn’t, and you want to make sure the pattern of slats is continuous from panel to panel. (Ask me how I know...) With a certain amount of huffing and puffing I was able to mount the SlatFusors on my own, though it would have been easier with a second person.

Peak Performance

Unlike DIYers, commercial manufacturers of acoustic products can and should provide measurement data from an accredited laboratory. GIK have been very diligent in this respect, and full test results from the University of Salford are available separately for the 25mm, 50mm, 100mm and 150mm‑deeptwo, four and six‑inch‑deep versions. As you’d expect, the main differences concern the low frequencies; the 50mmtwo‑inch version offers maximum absorption around 500Hz, with limited effectiveness below 200Hz, whereas the absorption coefficient of the 150mmsix‑inch version peaks at 125Hz and is still above 1 at 100Hz, suggesting it’s doing the most work in the range that is most problematic for small studios.

Another advantage of buying through a company like GIK as opposed to going down the DIY route is that they have acoustics specialists on staff who are able to offer professional advice and recommendations. I was aware that efforts to treat the low end in my own space had made it a bit too dead, without fully taming the bass. Simply installing yet more absorption would have made the midrange issues worse, especially as the hard floor is in a poor state and needs to be covered with rugs. There’s nowhere to easily fit panels behind the listening position, so GIK recommended installing SlatFusors on the front wall behind the monitor speakers.

There are usually multiple factors at play in any change you make to a studio, and in my case, fitting the SlatFusors also meant I had to slightly reposition my monitors. But the cumulative effect was impressive, and measurable. I used Genelec’s GLM software to generate reports before and after the process, and the ‘after’ results were substantially better, especially in the 80‑200Hz region. The room still benefits from EQ correction within GLM, but the degree of correction required is noticeably less, and a couple of sharp notches disappeared from the graph. The SlatFusors did exactly what they’re meant to do, helping to control the low end without over‑damping the midrange. They also look a lot smarter than the wall they’re hanging on!

With the SlatFusor, GIK have managed to put together a single product that combines both broadband and tuned absorption with an effective diffusor. Just a few will be enough to make a real difference in most rooms, especially if you have space for the 150mm version, but at the same time you can install as many as you like without the risk of over‑deadening the midrange and treble. Perhaps most impressive of all is the cost. Even if you had the patience and the skills to build something like the SlatFusor yourself, I think small‑scale DIYers would struggle to obtain the raw materials for all that much less than GIK’s full retail price. Save yourself the time and effort, let GIK do the hard work, and get on with making music!