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Acoustics Accessories

Mini-reviews By Paul White
Published December 2007

Primacoustic Recoil Stabilisers

Acoustics AccessoriesStudio loudspeakers usually sound best when mounted on heavy, solid stands, but sometimes desk-mounting is the only option. This can compromise the sound: most desks aren't as rigid as we'd like, so some of the energy transferred from the speaker cabinets causes the desk surface to vibrate slightly, which colours the sound. Furthermore, the loudspeaker cabinet moves slightly in reaction to the moving woofer cone, as the desk isn't rigid enough to hold it firmly in place.

Radial's Recoil Stabiliser might sound like something off Star Trek, but in reality it is a more elegant interpretation of my DIY concrete-slab-on-foam solution to this problem. In essence, a piece of very thick, very heavy metal plate is folded, so that it sits on a block of high-density foam with the folded end hanging over the front to improve the cosmetics, and the top of the plate has a non-slip mat fixed in place. The whole assembly is around 2.75 inches deep, with a platform size of roughly 10 x 14 inches.

The high-mass metal part, upon which the speaker sits, effectively adds to the mass of the speaker cabinet, thus reducing the amount by which it can move or 'recoil' when the bass driver moves. The foam is very poor at conducting vibrational energy, and isolates the monitor and plate from the desk surface — so less energy gets through to the desk. In practical terms, better isolation should result in a tighter bass end and better stereo imaging.

Tests with my Mackie HR624s produced noticeably better stereo imaging than mounting the speakers directly on the shelf surface, and the low end seemed much better controlled. Next to sorting out any basic acoustic problems, mounting your speakers correctly is probably the most important thing you can do to improve your monitoring accuracy, and if you're desk-mounting them, I can't recommend highly enough using some kind of isolation pad. The Recoil Stablilisers are the best I've tried, and though not the cheapest, the results make them well worth the price.

$99 each excluding shipping and VAT.

Primacoustic +1 604 942 1001.

info@primacoustic.com

www.primacoustic.com

Ghost Acoustics Studio Kit

Acoustics AccessoriesGhost Acoustics is a new brand from the people behind the SE Reflexion Filter. They've created a modular system of acoustic panels that, as with all SE products, are designed and produced within the company, so they can ensure good quality control while benefiting from the low cost of manufacture in the Far East.

Each absorbent panel is contained within a brushed aluminium frame, and is made from high-density (100kg per cubic metre) glass fibre and layers of aluminium foil, all of which is finished with fire-retardant polyester fabric. Most of the available modules are included in the ST3 Studio Kit, which was sent for review. This comprises four Blocks (the basic square panel, measuring approximately 60 x 60 x 8cm), one Gobo Stand, a Big Block (60 x 120 x 8cm), two Wedges (like the Block but increasing in depth from 8cm on one side to 14cm on the other) and two Corner Traps. Ghost have since added a hanging ceiling panel and a version of the Block that incorporates blue LED lighting to the range — very swish!

I installed the kit on the walls of a small room with 10-foot-high ceilings, which unfortunately means it is roughly cuboid — the kind of sub-optimal room that's all too familiar in home studio setups. The mounting system for the Blocks, Wedges and Big Blocks comprises a thin metal frame, which needs to be screwed to the wall, a process that's quick and painless, though you'll want a spirit level to get the placement right. The panels simply slot on to T-bolts that are built into the frames, pulling slightly against them to ensure a snug fit, so they don't rattle. Aligning the keyholes with the T-bolts is slightly fiddly, as you can't see them when the panel is placed over the frame, but this isn't a major issue. Due to the thickness of the frames, the panels themselves are slightly spaced from the wall (about 1.5cm) which should make them more effective.

With a pair of Wedges placed at the side mirror points, Blocks a little further back, and a Big Block behind my monitors, mid and high frequencies were tamed and there was a very noticeable tightening of the stereo image. I didn't have a ceiling panel to test, but as it is made of the same material, and the distance from the ceiling is adjustable, it should prove just as effective (if not more so, due to the adjustable height). I then installed the corner traps — the sturdy mounting frame is a little different, of course, but it is still the same basic approach. These made a significant difference to the bass end, which sounded tighter when I played a staircase test sequence over a few low octaves of sine waves. The traps proved a little large for such a small room — but that's a limitation of the room, not the traps, and they should work well in a larger space.

In terms of control room acoustics, there's little else to say — they're very effective, and they look great — but what makes them a cut above the usual acoustic foam is their flexibility. The Gobo Stand lives up to its name and is a useful way of mounting the panels, but the Blocks will happily stand on their own. With the stand, they can also be joined together to create larger panels. So, for the home recordist who mixes and records in the same space, these panels are hugely convenient: you don't have to store bulky gobos in addition to your room treatment; you just take them off the wall, place them where desired, do your recording and then simply put them back.

While it is difficult for acoustic treatment to have a 'wow factor', there is a good range of colours, and this system looks tidy and professional. They'll certainly appeal to those who are a fan of SE's 'industrial chic' — and the new blue LED version will improve on this still further. Though they're not exactly cheap, they are nonetheless good value, particularly considering the return you'll get over the years in terms of better recordings and mixes. This is a good and hugely flexible system that should appeal to both home and professional recording facilities.

ST3 Studio Kit £1250; Block £149; Wedge £169; Big Block £279, Corner Trap £169, Gobo Stand £79. Prices include VAT.

Sonic Distribution +44 (0)1582 470260.

info@sonic-distribution.com

www.ghostacoustics.com

Ready Acoustics Chameleon Acoustic Frames

Acoustics AccessoriesHigh-density Rockwool is a cheap and effective acoustic absorber, but it takes some skill to turn it into a good-looking trap. Ready Acoustics tackled this problem with their Ready Bag, a zip-up bag designed to take standard-sized Rockwool panels, but their Chameleon Acoustic Frames offer a more attractive solution.

The system comprises a set of metal side parts that screw together to form a rigid frame around standard Rockwool sizes. You can use any acoustically transparent fabric to give your trap a professional finish (or use acoustic foam in front of a thinner piece of Rockwool if you prefer that look). You supply the Rockwool and the fabric, Ready Acoustics supply the frames. Two depths are available (roughly 95mm or 50mm) and if your Rockwool isn't thick enough, you can always use wooden spacer strips to ensure a snug fit. The side pieces come in two-foot and four-foot lengths, so you can assemble panels of 2 x 2 feet, 4 x 2 feet or 4 x 4 feet.

The channel-shaped metal frame has punched apertures in the edges, and is available in six colours. You're only shipping the frames, so they're cheaper to transport than complete traps, especially if buying from outside the US. Assembly is simple — lay your fabric out flat and lay your slab of Rockwool on top. Fold the fabric around the edges of the Rockwool, push the frame parts onto the Rockwool's edges and screw together with the included screws. You can put thin fabric on the back, as well, in order to prevent any Rockwool fibres escaping — something that's cheap and easy to do before fitting the frames. The frames are made from folded steel, with keyhole slots cut into one edge for wall-hanging, but these are rather small so I had to drill them out slightly.

The edges of the frame are punched out to allow sound to pass through, so the traps are only as effective as the Rockwool inside, but as with most such traps you can improve their low-frequency performance by spacing them off the wall a little.

I put one 2 x 4 frame together, using two sheets of 30 x 600 x 1200mm Rockwool and one of two-inch Auralex foam (to match the rest of my studio) without any problems. Though the metric Rockwool sizes are slightly smaller than the imperial, the frame lips are adequately deep to accommodate it. If you use fabric, which I'm sure most users will, you'll need to ensure the Rockwool is a snug fit inside the frame and my inclination would be to use spray carpet adhesive on the edges and rear of the Rockwool in order to discourage the fabric from slipping.

The finished panel is quite heavy; one person can lift it, but you may need help guiding the keyhole slots onto the screwheads. Ready Acoustics also supply small S-shaped hooks that allow you to hang the panels on chains (which are available from any DIY store), and you're thus able to hang the panels across corners to increase their bass trapping efficiency.

I was really impressed with the Chameleon traps, as they turn a chunk of cheap Rockwool into a very professional-looking trap for relatively little cost, even taking shipping and import duty into account.

$34.99 each; $360 pack of 12. Prices exclude shipping and VAT.

Ready Acoustics +1 612 817 8844.

email via web site.

www.readyacoustics.com.

SE Electronic Instrument Reflexion Filters

Acoustics AccessoriesSE's original Reflexion Filter is an acoustic absorber, designed to reduce the amount of room ambience getting into a microphone during recording. It comprises six main layers behind a punched aluminium frame, which is how it manages to be so effective without having to be hugely thick. It's intended mainly for vocal recording, and though it can be used in some instrument applications, there was clearly a need for a smaller product, for use in situations where space and weight are major considerations.

SE have therefore produced the Instrument Reflexion Filter — but it isn't just a smaller version of the original. It is slightly simpler, with just three absorbing layers behind a punched-aluminium outer screen that protects the inner materials while providing useful diffusion. The absorbing layers are well-spaced, so as to maximise absorption. Around a quarter of an inch thick, it is fairly rigid, but you can blow through it, which means sound can pass through but energy is absorbed, and each successive layer absorbs a little more.

The screen measures just 6.5 x 8 inches, and merely scaling down the original design wouldn't accommodate a pencil mic (let alone one with an XLR plug stuck into the back of it), so the new design includes an aluminium tube that allows most pencil mics to poke through (an acoustic plug fills the hole for use with side-address microphones), and a spring-loaded plunger at the side of the tube holds the mic firmly in place, so a single mic stand can hold both Filter and mic.

The mounting arrangement is a 12-inch gooseneck arm with a mic-stand clamp on one end, so if you use normal boom mic stands to position drum overhead mics, you can angle the mic and screen to any position you're likely to need.

Reflexion Filters work in two ways: they help screen the rear and sides of the microphone from reflected sound or spill from other instruments; and they reduce the amount of the original sound escaping into the room to cause reflections. The larger, original version used in close proximity to a vocalist is more successful in containing the source sound than a smaller version placed at some distance from an instrument; in most instrument miking situations, you can pretty much discount any reduction in the source sound getting out, but because of the central tube, you can get the Instrument Reflexion Filter very close to the microphone, creating a wide 'acoustic shadow' that intercepts room reflections before they reach the rear and sides of the mic. This is particularly useful when recording drums in non-optimal rooms, where ceiling reflections getting into the overheads can be a major problem. By keeping the overhead mics fairly dry-sounding, you can add back a plausible live room sound using a suitable reverb — whereas adding reverb to poor room ambience rarely works well.

I've used the full-size Reflexion Filter on a number of acoustic guitar recordings, and it is particularly effective with omni or figure-of-eight mics. The instrument version makes it easier to get the mic in the right place because of the central tube, and much easier to position without getting in the way of the performer. I find that an omni mic gives the most natural sound on acoustic guitar, and the Reflexion Filter means I don't have to worry about it picking up too much room ambience from behind. The Filter is also helpful when recording electric guitar cabinets with figure-of-eight ribbon mics, though the full-size version offers slightly more effective rear screening and the size is rarely a problem.

At about half the price of the original, the Instrument Reflexion Filters are good value and very practical. I can't stress enough how important it is to minimise ceiling reflections when recording drums in small rooms, and though a screen this size can never be 100 percent effective, the difference is well worthwhile. If you just need a pair to do the occasional job, you can buy them that way but you can also get a set of five in an aluminium flightcase, which makes sense if you do a lot of location recording. 

£119 each; set of five with boom stands £500. Prices include VAT.

Sonic Distribution +44 (0)1582 470260.

info@sonic-distribution.com

www.sonic-distribution.com

Published December 2007