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Studio SOS: The Lab

Flying Duvet Remedies
By Paul White

Paul scurried onto the roof of the girls' drum booth to apply some more acoustic treatment, most importantly hanging a spare length of heavy felt carpet underlay over a crossbeam as a limp-mass absorber — you can see this hanging down behind the duvet in the background.Paul scurried onto the roof of the girls' drum booth to apply some more acoustic treatment, most importantly hanging a spare length of heavy felt carpet underlay over a crossbeam as a limp-mass absorber — you can see this hanging down behind the duvet in the background.

Flying duvets provide an emergency remedy for control-room acoustics in The Lab's two-storey industrial unit.

Jessica Farrar and Eve Horne both trained in sound recording and music-industry studies at the Gateway School of Recording when it was on the Kingston University campus. After graduation, they set up as the production duo She Devil, under the Continuous Entertainment umbrella, and also have studio and songwriting endeavours. Their studio, The Lab, is in an industrial complex near the Royal Arsenal by the river Thames, and in 2005 won the Social Enterprise Of The Year award at the National Business Awards. One reason for this award was that the duo wanted to make their studio affordable for anyone in the community who could benefit from it, so it's very much about being accessible.

Problems In The Lab

The girls did most of the building work themselves, as they were launching their business on a grant given to them by the Prince's Trust, and we were called in because they found their mixes didn't travel as well as they might — they were nearly always bass heavy. Their system is relatively simple, based around a Mac G5 computer, and comprises Apple Logic Pro 7, Digidesign Pro Tools LE and Digi 002 interface/control surface, and an analogue Yamaha desk. Monitoring is via Alesis M1 Active MkII speakers, and they have a small selection of good-quality microphones.

Jessica and Eve built a live room as a single-storey 'box' within their two-storey industrial space, which left them with a two-storey-high control room that also coupled directly into the space above the live room. The steeply vaulted ceiling was entirely glass on one side, which lent an airy feel to the studio, but also produced unwanted reflections. They'd set up their Yamaha mixer and Alesis monitors in front of the control-room window looking into the live room, which left them with a hard, reflective entrance door and wall behind them. They'd used some acoustic foam tiles around the side walls, but there were not enough of them to tame the coloration of the room, much of which came from the high ceiling.

The high ceiling in Jessica Farrar and Eve Horne's two-storey industrial unit was causing real problems with the control-room monitoring environment, so Paul had them buy a couple of king-size duvets and string them from the unit's suspended wiring conduits as a quick fix — and it worked surprisingly well!The high ceiling in Jessica Farrar and Eve Horne's two-storey industrial unit was causing real problems with the control-room monitoring environment, so Paul had them buy a couple of king-size duvets and string them from the unit's suspended wiring conduits as a quick fix — and it worked surprisingly well!

The twin LCD monitors for the G5 computer were positioned to the right of the desk, making mixing and post-production work less than ideal, as the monitor speakers were off to the side. The speakers were also standing directly on a wide desk, inviting reflections up from the surface of the desk, and they were also a little too low, as the tweeter should, ideally, be close to ear height. Because of this less-than-desirable monitoring environment, the girls had been misjudging the amount of bass end in their mixes, resulting in them producing tracks with far more low end than necessary.

They'd also been applying fairly radical EQ to clean up their recorded vocal sounds, which had suffered not only because of the monitoring, but also because the live room had two of its three walls covered in carpet — while this looked good, it left the room sounding very boxy. The fourth wall was covered in two-inch and four-inch thick acoustic foam squares, but the very selective absorption of the carpet (only very high frequencies are absorbed) and the lack of bass trapping conspired to colour the recorded sound very noticeably, and also produced a vocal 'honk' at around 300Hz.

Room Treatments

After plundering the girls' stash of biscuits and discussing the problem, Hugh and I agreed that the room would work better if the monitors were moved to the side wall, either side of the two flat-screen computer monitors set up on a narrower work top. This would place the monitors in view while mixing, and also allow the wall behind the mixing position to be treated more effectively, as it wouldn't contain doors and also had a settee in place for clients. Soft furniture is always welcome where you want to kill reflections! There were also three small foam panels on the wall, and adding another Auralex panel was enough to kill the worst of the reflections from that source.

In order to improve the stereo imaging of the monitoring system, Paul added some extra Auralex acoustic panels to the walls around the speakers.In order to improve the stereo imaging of the monitoring system, Paul added some extra Auralex acoustic panels to the walls around the speakers.

More Auralex foam was used on the walls each side of the listening position to improve the imaging. A filing cabinet was standing in a corner between the mixing position and the right-hand wall, so its side was also covered with a foam panel. Two further panels were placed between the monitors, above and below the panels the girls had already fixed in place. This took care of the early reflections and improved the stereo imaging, but of course there was still the problem of the very high ceiling and void above the live room to deal with. To do a rigorous job on this would take time and money, but we needed to come up with a quick, pragmatic, and affordable solution, so Hugh and I retired to the local coffee house while we sent Eve and Jessica shopping for king-size duvets...

Two robust wiring conduits ran across the room about 12 feet from the ground and supported the strip lights. Our plan was to hang a couple of king-size duvets between these conduits using nylon cord tied around their corners. This task would have been simple had the ladder available to us been four or five feet higher, but, as it was, fixing the duvets in place involved some precarious balancing work! Once in place, these duvets made a very significant difference, drying up a lot of the most audible coloration at a stroke.

Hugh propped a pair of Real Traps Mini Traps across the rear corners of the room to tighten up the low-end response.Hugh propped a pair of Real Traps Mini Traps across the rear corners of the room to tighten up the low-end response.We had also been supplied with a couple of Mini Traps by the manufacturer Real Traps, and we propped these up across the rear corners to help even out the bass end — more of these would have been useful in a room of this size, but in combination with the other tricks we'd tried the acoustic was starting to sound more controlled. We recommended that (when a suitable ladder became available!) the girls make a more permanent job of fixing the duvets, ensuring that they hung evenly, and far enough away from the light fittings. As it was, the strip lights were rarely used and produced very little heat anyway — all the same, it would be good to ensure a gap of several inches between the lights and the duvets. The girls had tended to use up-lighters on the floor to generate a diffuse lighting effect when working at night, but with the duvets obscuring the fluorescent light fittings quite effectively, the diffused light improved the overall aesthetic feel of the studio too.

A final tactic was to climb up on top of the live room and hang a spare length of heavy felt carpet underlay over a metal crossbeam to act as an impromptu limp-mass absorber. There were other crossbeams that could be used to support more material (curtains and carpet could be useful here) but the girls would have to find some way to obscure this from being seen through the window, as even our solitary piece of carpet felt looked rather untidy from outside the building.

Sequencer Processing Tips

While experimenting with some of the girls' mixes, we tried a few processing tricks using Logic that the girls were keen to try again later. One was that old chestnut of using a tempo-sync'ed delay or panner to add life to guitar and synth parts, and we also added a bit of welcome edge to a synthesized kick drum using Logic 's Phase Distortion plug-in. Hugh and I also advised the use of Space Designer as a main reverb, as it sounds much classier than Platinumverb and includes both real spaces and 'sampled' hardware reverbs and plates. For vocals, we found a nice bright plate setting, and then rolled off some low end to give a very polished sound that didn't fill up all the space with unnecessary reverb.

When EQ'ing the vocals, I replaced the earlier radical EQ with a slight cut at around 300Hz to take out the worst of the live room's honkiness, and also added just enough 10-12kHz broad-band boost to add clarity and focus to the voice. Hopefully the mid-range cut won't be needed once the problems in the live room have been addressed. I also demonstrated that EQ'ing some low end out of pad sounds could open up the mix, and that, where a sound lacks clarity and EQ can't put it back, Logic 's Exciter plug-in is sometimes just what you need, especially with synthetic percussion sounds.

If a mix is getting out of hand insomuch as some of the levels are peaking, you can select multiple channels in Logic 's Environment page and then pull them all down by a few decibels to get back some headroom without upsetting the overall balance. Of course this doesn't work if you've already added level automation, as the faders will simply return to their automated positions, but you can use the gain control on Logic 's Channel EQ or Compressor plug-ins to trim the gain back on these channels, or you can simply insert the Gainer plug-in and use this to bring the gain down without altering the way the overall automation works. This selecting of multiple channels in the Environment page also works for setting up sends to busses, where you want the same sends to be used on several different mixer channels.

Finally, I set up Logic 's Multipressor to add polish to their mix, and although you shouldn't do this to material that is due to be mastered, it is a good way to get demos sounding good. I adjusted this to cover just three audio bands, with the split points around 120Hz and 5kHz, then set low compression ratios of around 1.2:1 in the high and low bands and 1.1:1 in the mid-band. Combined with a low threshold of between -35dB and -45dB, this produces a gentle thickening effect that makes the mix seem more homogenous, and if you pull down the mid-band by a decibel or so, the impression of loudness and clarity is enhanced. I followed this up with Logic 's Adaptive Limiter set in such a way that the peaks were reduced by no more than 3dB, achieving the maximum possible loudness without damaging the subjective sound of the track.

Listening Tests

To get the speakers to the correct height, we had to experiment using boxes full of the studio's marketing literature as impromptu supports, but recommended that these be replaced with something solid, such as bricks or concrete blocks, at the earliest opportunity. Simply sitting the speakers on blobs of Blu-Tac on the bricks would be fine, with perhaps some dense foam or non-slip mat underneath to help isolate vibrations from the table surface. As usual, the speakers were angled in towards the listening seat, and now that the speakers were on a much narrower surface, reflections from the table were much less of an issue.

With the acoustic treatment in place, Paul loaded up some of the girls' projects in Logic, and passed on some of his top tips.With the acoustic treatment in place, Paul loaded up some of the girls' projects in Logic, and passed on some of his top tips.Listening tests using our standard test CD showed that not only was the room coloration greatly reduced, but the stereo imaging was now very well focused, whereas it had been almost non-existent before. Those duvets in the ceiling, while not effecting a complete cure, had damped out an enormous amount of the boxy coloration coming from the high ceiling, and in combination with the additional foam and Real Traps, this made the room feel very different to how we'd found it a couple of hours earlier. The degree of bass build-up towards the entrance door had also been reduced, and the sound balance remained creditably even throughout the room. More importantly for keeping clients happy, mixes sounded good and evenly balanced when sitting on the sofa. Prior to this, the perceived level of bass on the sofa was somewhat different to that in front of the monitors.

Playing some mixes the girls were working on showed them now to be quite bass heavy — as I had expected — though we were more than impressed with their general choice of sounds and arrangements. This just shows how misleading an inaccurate monitoring environment can be, and it was the reason why their mixes always sounded somewhat bass heavy on other systems. The radical vocal EQ could now be reduced to something closer to normal, and after a few minutes re-balancing and EQ'ing of their mix, we got it sounding very sweet, with a sensible level of low end.

Live-room Recommendations

We didn't have time to make any changes to the live room, but we did make some recommendations. Firstly, the recorded vocal sound would be better if the singer stood with their back to the wall covered with thick foam. If more foam could be used to create a vocal corner that the singer could back into, the results should be cleaner still. After all, a cardioid mic hears sounds mainly from in front and to the sides, so having absorbent surfaces behind and to the sides of the singer is the best way to keep the sound clean. On some of their mixes, the vocals had been compressed rather more heavily than usual, and an inevitable side-effect of this is that any room coloration is further exaggerated when the compressor brings the gain up at the ends of words.

The live room had three of its walls covered in carpet, while the other wall was covered with acoustic foam tiles of different thicknesses. The very selective high-frequency absorption of the carpeting combined with the lack of any bass trapping conspired to produce a coloured recorded sound, with a pronounced vocal 'honk' at around 300Hz.The live room had three of its walls covered in carpet, while the other wall was covered with acoustic foam tiles of different thicknesses. The very selective high-frequency absorption of the carpeting combined with the lack of any bass trapping conspired to produce a coloured recorded sound, with a pronounced vocal 'honk' at around 300Hz.This room was also to be used for recording guitar and drums, so we had to come up with a way of reducing the effects of the carpeted walls and re-balancing the reverberation time across the entire spectrum. Without resorting to a solution outside the available budget, the best way forward would be to add back some high-frequency reflections and diffusion, while also introducing some bass trapping to take care of the low-end boom. High-frequency reflections are easy enough to deal with by using small areas of reflective material such as wood strips or plastic sheets scattered around the walls. We've even used old CDs to do this on previous jobs! A cheap solution is to cut strips from laminate flooring and glue these directly to the carpet on the walls, adding a few at a time and stopping regularly to evaluate the results.

Bass trapping requires a little more work, but still need not be expensive. Given a healthy budget, Mini Traps suspended in the wall-to-ceiling corners would work well, but as there was little budget left we suggested using 30mm or thicker Rockwool cavity-wall slab along the wall/ceiling boundary fixed at 45 degrees using simple wooden battens as fixing supports. The face of the trap could then be covered in fabric, or even porous carpet. To judge how much trapping is required, it should be possible to lay out the slabs between the floor and wall corners and then make some test recordings. Playing back bass lines through a speaker in the live room and then checking the bass level is even for different notes is also a simple way of checking that the amount of bass trapping is adequate. Once the amount of trapping has been decided, it can then be fixed to the wall-ceiling boundary in a permanent fashion. The traps can be made more effective still by filling the space behind them with insulation-grade Rockwool, but this isn't essential. Knowing how the girls love the power-tool section at B&Q, this should easily be within their DIY capabilities!

Another problem with the live room was sound leakage through and around the single fire door separating it from the control room — even though the girls had used neoprene door strips to try to effect a proper seal when the door was closed. An industrial compression latch that forces the door against the surrounding seal will help, but the best solution here is to add a second fire door. Even two doors separated by the thickness of a stud partition wall can bring about a significant improvement in sound isolation when compared to a single door. These doors cost only around £20 each here in the UK, so it is a very cost-effective solution and undoubtedly the best option here.

System Tweaks

Currently, a Yamaha four-buss desk is being used essentially as a set of mic preamps feeding the four line inputs on the Digi 002. There's also a Focusrite voice channel that can be patched directly into the Digi 002. Whichever way you play it, you can only handle a maximum of eight inputs at a time using the Digi 002 (it has four mic preamps of its own) so for larger projects, a different audio interface might be advisable. A multi-channel interface that can be expanded via one or more ADAT ports is a good option, as there are now several eight-channel mic preamps with ADAT I/O on the market that can be added to such systems. This would make the Yamaha mixer redundant, freeing up desk space and budget, but the Digi 002 would have to stay for those projects that need the capabilities of Pro Tools. It would also be worth looking at the possibility of using its moving-fader interface to control Logic Pro, as mixing by mouse alone can be very frustrating.

The girls had created a door seal using neoprene strip in order to try to reduce the sound leakage from the live room into the control room, but this wasn't very effective. Paul suggested that a compression latch might improve matters, as would adding a second door.The girls had created a door seal using neoprene strip in order to try to reduce the sound leakage from the live room into the control room, but this wasn't very effective. Paul suggested that a compression latch might improve matters, as would adding a second door.The studio also has a Roland JV1080 synth module which the girls were playing live from a MIDI keyboard, recording the audio output. I showed them how to set up Logic 's Environment page to allow more freedom to edit the MIDI data or change patches while working up a song, before committing the audio to Logic just before mixing.

Overall, this was one of our tougher Studio SOS sessions, because of the difficult shape of the control room, but our duvet 'clouds' and additional foam panels tamed it to the extent that we now felt it was a much better mixing environment. I still wouldn't recommend doing final mastering in the room, as neither the monitors nor the room acoustics are accurate enough for such a critical application, but then this is true of all but the best professional studios too. Any remaining mix EQ issues should now easily be fixable by a mastering house, and our listening tests showed that the monitoring system was now giving a much more accurate impression of the music played through it. The recommended changes to the live room should improve the tonal balance without incurring too much cost, and adding that extra door should improve the isolation between the control room and live room to a worthwhile degree. More hanging material in the void above the live room should help tame the control-room acoustics further, but the improvement in the room after the addition of the duvets, foam panels, and Mini Traps was very significant and immediately obvious when you walked into the room.

The girls are clearly very talented as producers, with some great arrangement ideas, but they were being frustrated by acoustic problems that they could hear, but that they felt couldn't be solved professionally within their budget. Our pragmatic solutions may not have been quite up to what you'd get in exchange for a £50000 cheque, but they did make a very worthwhile improvement and have brought their room up to the standard where most people should be more than happy mixing in it. 

Session Impressions

Studio SOSJessica Farrar and Eve Horne: "The control room was our main problem, with the room being so spacious, so much so that we had reverted to mixing mainly on headphones in order to obtain the stereo image we needed! However, that didn't help our problem with bass overload in our tracks... As Paul and Hugh worked their magic, we were amazed at the difference in the sound of the room, and it was reassuring to find out that it was indeed the acoustics that were to blame."

+44 (0)20 8301 8668.

she_devilproductions@yahoo.co.uk

www.thelabonline.com

Published May 2006