Studio SOS: Cube-shaped Room

Setting up your studio in a cube-shaped room isn't a very good idea, as Pete Keen and Nick Smith found out to their cost. So the SOS team set off to Kidderminster to help find some solutions to the inevitable acoustic problems.

Pete Keen and Nick Smith have no problems writing music or finding an outlet for it — they have just completed the soundtrack to a short film called Just The Ticket shown at the Cannes film festival in May this year. In fact, it was this project that convinced Pete and Nick that it was time to upgrade their studio from an early Mac G4 to a shiny new G5, because running videos within the Pro Tools software on their old system was, as Pete put it, like wading through treacle!

Pete and Nick had tackled the bass problems resulting from the dimensions of their studio room by building an asymmetrical false ceiling (shown above), containing four-inch-thick furniture foam (in blue) for absorption. However, this treatment caused almost as many problems as it solved.Nick works at Worcester College of Technology, which runs a well-respected music-technology course and has a couple of professionally designed studios. Nick had taken in some mixes to check them over, and he was horrified to discover that they sounded nothing like the same mixes played back in the bedroom studio. Unfortunately, this particular bedroom studio is almost a perfect cube, which is the worst possible shape for a studio — other than perhaps a perfect sphere! Nick borrowed some acoustic panels from the college to see if anything could be done to improve the room, and after propping some of these against the ceiling using ladders and mic stands, he and Pete felt the sound was better, particularly at the bass end.

As a result of this experiment, Pete's woodworking skills were put to use building a false ceiling with holes cut into it, behind which could be wedged a generous amount of four-inch furniture foam. As Pete has connections in the furniture business, large amounts of foam seemed easy to come by, but although they made a fabulous job of the ceiling, complete with routed triangular cutouts, Nick had somehow got it into his head that studios should be asymmetrical about the monitor axis, and so he'd designed in an angle (effectively an inverted apex) about one third of the way across the ceiling. The pair had also decided to build similar structures on the two side walls, and had got as far as building the timber framing for one side when Nick called SOS for help.

Sorting Out A Small Cube Room

Hugh and I decided this might be an interesting challenge, a decision in no way biased by the promise of chilled chocolate Hobnobs (plain and milk!), so we soon found ourselves in a very compact bedroom studio on the outskirts of Kidderminister. The room was approximately nine feet square, with a ceiling height of around eight feet, though the false ceiling had brought this down to around seven feet at the lowest point. Pete played some commercial records back through their Tannoy DC100 dual-concentric passive monitors and explained that the ceiling had definitely helped to even out the bass end, but we all agreed that the overall sound was still somewhat muddy.

The speaker drivers were still too high for optimal monitoring, even from a standing position, so Hugh turned the speakers on their sides to lower the drivers to a more suitable level.

Because Pete suffers from back problems, he finds it easier to work standing up rather than sitting down, therefore the speakers had been placed on a high shelf. This resulted in the coaxial drive units being well above ear height, even when standing. Hugh cured this problem by simply turning the Tannoy speakers on their sides, therefore lowering the tweeter axis by eight inches or so. With most conventional monitors, turning them on their sides is usually a bad idea, because it corrupts the horizontal dispersion, but in the case of the Tannoy dual-concentric the dispersion is symmetrical in both the horizontal and vertical planes.

As it stood, the studio system was set up on a worktop that ran the full width of the room. It was quite congested, and it also made it difficult to make the room acoustically symmetrical, because there was a wall full of shelves to the left of the mixing position, and a window to the right.

Although the ceiling bass trap seemed to be fairly effective in controlling the inevitably bunched standing waves of the square room, the asymmetrical design didn't do the stereo imaging any favours at all. Asking Pete and Nick to rebuild their impressive ceiling trap would clearly have gone down about as well as a plate of stale digestives, so Hugh suggested turning the studio through 90 degrees, placing the monitors either side of the window. In this way, the ceiling trap would become symmetrical as far as the monitors were concerned, and the inverted apex might even prove beneficial in terms of bouncing early reflections away from the monitoring zone. We felt that the partially built wall frames were unnecessary, and could be dismantled. Another useful side-effect of the suggested new layout was that the bench would run down the left-hand side of the room, and the shelving full of books and accessories would be at the back of the room, providing useful scattering and diffusion. The monitors could also then go on proper stands or sturdy wall brackets, and there would be room on the wall either side to affix some foam panels, taking care of side-to-side reflections at the monitoring position.

The Tannoy speakers themselves sounded a little tired and flabby to our ears, and as Peter and Nick were already considering upgrading to active monitors I agreed to bring along the Mackie HR624s that I normally use as rear surround speakers to see how they worked out in that particular room. As they were mixing and processing entirely within Pro Tools, we also suggested that a master control box similar to a Samson C•Control or Mackie Big Knob would be useful, as it would allow them to handle headphone monitoring and the connection of two-track recorders and players without having to re-patch.

With our suggestions carefully documented, we left Peter and Nick to tackle the changes, offering to return once the supply of chocolate biscuits had been replenished...

Happy Returns

On our return, the studio had been transformed, with the previously cluttered bench now supporting only the necessary equipment, and an impromptu desk set up beneath the window to hold the flat-screen monitors and computer keyboard. The G5 was purring away on the floor beside the desk, and the Tannoy DC100s were standing on blocks and ladders so that we could confirm correct placement before they did anything too permanent.

On their return, Hugh and Paul found that the whole studio layout have been changed along the lines of their suggestions, and they could then set about positioning the Tannoy monitors for the best sound — the ladder was used as a temporary stand while experimenting with different speaker positions.

The half-built wooden frame on the right-hand wall was gone, and on the side walls they'd fixed some more furniture foam, topped by some Auralex panels — the extra thickness of foam would absorb to a lower frequency, though it probably wasn't essential. They'd also finished wiring the ceiling lights and crammed even more foam into the ceiling to improve its effectiveness at low frequencies. Finally, because the studio had been rotated by 90 degrees, the newly built ceiling was now nicely symmetrical about the monitoring axis.

The sonic improvement surprised even us, as cube-shaped small rooms are definitely bad news for audio accuracy, especially when they are this small. What we discovered was that the bass was very even and consistent everywhere in the room apart from a beach-ball-sized volume, which we nicknamed the 'zone of death', exactly in the centre of the room — here, the bass just disappeared completely. However, provided that this zone was avoided, the monitoring seemed pretty accurate and reliable everywhere else (except very close to the walls, of course). The stereo imaging was astonishingly good too.

Moving the Mackie speakers to the window sill demonstrated how much the placement of the speakers affected the sound — the bass end immediately became much less reliable.

Next we tried out the Mackie monitors. The bass end felt even more controlled and the high end detail was more revealing than with the Tannoy passive speakers, and both Nick and Pete agreed that they were now hearing things in their mixes that simply weren't audible before. Although Peter wanted to use wall brackets to hold the speakers, I strongly recommended stands, as they give you the opportunity to fine-tune the speaker position for the best results. After seeing how easy it was to build our SOS DIY stands (as shown back in April's Studio SOS article), he resolved to build his own from timber.

Just to demonstrate how important speaker positioning is, we moved the Mackie monitors from either side of the window onto the window ledge. The sound changed dramatically — for the worse at the bass end. A little further experimentation confirmed that stands either side of the window, but away from the room's corners, would be difficult to improve upon.

Box Clever

This Studio SOS visit showed that, although small square rooms are generally bad news for audio, they can be made usable by applying appropriate acoustic treatment, provided that you're careful about where to sit and where not to sit when mixing. Pete and Nick are planning to use this studio for a couple of years while they have a garage built, which will free up enough space for them to do the job properly. While I'd be the last to claim that they now have perfect acoustics, the improvement is enormous — they can at least hear the detail and stereo imaging of their mixes and make a fair stab at judging the level of bass in a mix. They shouldn't try to master their own mixes in this room, but that doesn't mean that they should have any problems doing mixes for fine-tuning at the mastering stage.