Primacoustic London Systems

We check out these integrated kit solutions to room‑acoustic problems in the project studio.

Applying adhesive to a Scandia Scatter Block, and installing an Australis Corner Trap.Acoustic treatment can be as simple as a couple of a foam tiles and a duvet, or it can entail the ground‑up design and construction of a studio interior, including bass traps, diffusers, absorbers and so on. Fortunately, while large commercial studios with thick, dense walls and large monitors can be expensive to treat effectively, home‑based project studios can usually be treated fairly cost effectively, partly because they are smaller, but also because there are fewer bass problems due to the use of nearfield monitors.

The main elements of minimal acoustic treatment comprise absorption panels at either side of the listening position (to kill flutter echoes and to reduce early reflection from the speakers) augmented by some rear wall absorption, and perhaps some further absorption on the ceiling above the mixing console and behind the monitors. Additionally, a degree of bass trapping may be desirable, though where there are large areas of windows and doors, this may not be necessary where smaller nearfield monitors are being used, as windows and domestic doors reflect very little low frequency energy — it goes through instead!

Many studio owners go for a 'suck it and see' approach to acoustic treatment using off‑the‑shelf foam panels, and this can work well enough in small rooms, but foam panels alone are only effective down to somewhere between 250 and 400Hz, which means they are of little help where bass trapping is required. Canadian company Primacoustic have come up with a modular acoustic treatment system based on pre‑cut blocks and wedges of high‑density, open‑cell polyurethane foam that includes corner‑mounting bass traps. This takes a lot of the guesswork out of acoustics, as detailed instructions are included, yet the design of the individual panels allows plenty of flexibility when dealing with non‑standard rooms. The installation guide and technical notes tied in with what I've learnt about project studio acoustics over the past few years, which made me feel fairly comfortable about installing the kit in my own studio for the purpose of this review. Though the UK cost is a little higher than buying general‑purpose foam tiles, the end result looks very professional and the higher density of the foam makes them more effective than lighter foam panels.

The London 14 System

The system comprises a series of panels that can be assembled to form mid‑range and high‑frequency absorbers to deal with side‑to‑side and front‑to‑back flutter echoes, plus a number of smaller 'scatter blocks' that can be used on the ceiling, rear wall or elsewhere to increase absorption. Bass trapping is accomplished by large foam corner wedges and the kit includes sufficient adhesive (tubes of No Nails) to fix everything to the walls — all you need is a regular mastic gun to apply it.

I don't know if it's because the guys behind this are Canadian, but everything in the system has rather a strange name. The kits for various size studios are named after cities, which is fair enough, and I chose the London 14 kit as it is designed to treat a room about the size of a single garage. This contains something called the Europa Flutter Wall to provide absorption at the front of the studio, a pair of Orientique Washboards (I told you the names were weird!) for treating the side walls, four Australis Corner Traps and 24 Scandia Scatter Blocks. Both the flutter wall and side walls comprise foam panels of varying thicknesses up to around 2.5 inches, some parallel‑faced and some wedge shaped, which when combined look rather neat. Numerous design examples are shown in the installation guide, based on arranging the panels in a different order, and all the patterns are given interesting names.

Above and below: The two Orientique Washboard side wall diffusers installed in Paul White's control room.The side wall panels (washboards) end up being three feet square while the flutter wall is three feet by six feet. Of course you can assemble the panels into smaller sections if you need to, and in my case I didn't even use the front‑of‑room flutter wall kit as I have little free space there and, in any event, the existing treatment works fairly well in that area. Neither did I use any ceiling panels, as the ideal place to put them coincided exactly with my halogen light fitting. Furthermore, the installation instructions show one bass trap in each corner of the room, but, because of the way my room is set out, I opted to put all four in the rear corners instead. Each bass trap is three feet long and extends 12 inches from the corner in both directions, but if you feel this might take up too much valuable room, you could fit them into the corner between the wall and ceiling instead.

All the panels and traps are held in place using only adhesive, though the installation guide suggests that you can use plasterboard metal corner bead fixed to the wall at the bottom of each set of panels or traps to ensure a straight, horizontal edge and to prevent any slippage while the adhesive is setting. In practice, I didn't find this to be necessary, as the adhesive grabs straight away, but it is important to mark horizontal and vertical pencil lines as guides before you start. Also, because the bass traps are heavier than the panels, I supported these from beneath for a couple of hours to give the adhesive time to set.

The scatter blocks come as wedge shapes and are generally used in pairs to provide either a concave or convex 12‑inch‑square module. Rather than put them all in one place, the idea is to scatter them over the rear wall to provide alternating areas of absorption and reflection. In my room, the back wall of the studio includes a large pair of French windows, so clearly I couldn't stick the blocks to those. Instead, I used the scatter blocks to cover the space above the door for the full width of the room and decided to treat the reflections from the door using a heavy curtain. As luck would have it, the strip of wall above the door was slightly less deep than the depth of two scatter blocks so I had to cut several of them down by about an inch and a half (this stuff is Canadian so no metric measurements here!). I found that most useful of studio tools, the electric band‑saw, did this beautifully, leaving a perfectly straight edge, but, if you happen not to have one, an electric carving knife does a neat job. A few scatter blocks were left over so I put a row of these above and below the side absorbers to hide the glue marks where I'd taken down my original home‑made absorbers.

Because I know my studio room pretty well and have experimented with various acoustic treatment options over the years, I felt confident in not deploying the kit exactly as specified, but for the less experienced user, I think it would be wise to stick as closely to the plan in the installation guide as possible. The modular nature of the panels means there is plenty of flexibility to cope with non‑standard rooms, and in studios that have a control‑room window, the front flutter wall components can be split up and placed around it, provided that symmetry is maintained.

Fixing the kit turned out to be extremely simple and only took a couple of hours. You have to take care not to get glue on the face of the tiles or it spoils the appearance, but this isn't difficult, provided that you're reasonably careful. Of course once the kit is up, you can't get it down again without leaving glue all over your walls — where you may need to uninstall at some later date, the guide suggests fixing light ply panels to the wall and then tiling onto those.

Absorbing?

So far then, the kit is easy to install and it looks pretty smart too, but what does it sound like? Although I had treated my studio before (albeit fairly minimally) and was happy with the mixes I was getting, the Primacoustic system definitely dried up the room from the mixing position, reducing side reflections and improving the stereo imaging quite noticeably. My original bass traps were quite bulky and used a lot of messy Rockwool and roofing felt, so the extra space afforded by the foam replacements was welcome. I didn't notice any reduction in the level of perceived bass in the room, but felt the bass response to be more even and slightly tighter than before.

Primacoustic don't make any exaggerated claims for their system, and they certainly don't say that you will end up with a perfect room. What you will get is a room that is sufficiently well behaved on the acoustics front to do serious work in and where any deviations from the norm are small enough that you can adapt to them, provided that your speakers don't have too much bass extension. The bass traps are effective down to around 45Hz, while the wall panels absorb mainly above 400Hz, but are still quite absorbent at 200Hz. At very high frequencies, the tiles are slightly reflective, something the manufacturers describe as 'soft diffusion'.

The company also points out that all foam tiles are flammable to some extent, even those made of fire retardant materials (it seems the Canadian regulations on this are tougher than ours) so, while they are fire resistant to a reasonable extent, care must still be taken by the user to determine suitability. Apparently the foam may also be coloured by spraying it lightly with a latex‑based paint.

Using this system, a typical project studio can be treated for between £600 and £1200 pounds, which is not a lot to pay for a tidy and effective solution. Kits are also available for treating vocal booths. I found the installation simple and was pleased with the results — there was a noticeable improvement in clarity, imaging and evenness of bass. I would agree with the manufacturers when they say that the only way to get a perfect room is to have it designed and built by studio professionals, but as a real‑world solution for project studios, the Primacoustic approach certainly works and I look forward to doing more mixes using it.