Studio SOS: Taming A Large, Live Room

Ever wondered how to tame a large, lively room without drills, nails or glue? Or how best to mount monitors without speaker stands? Then read on to find out how we helped Simon Mayor and Hilary James.

Simon Mayor (right) and Hilary James (left) have been playing the mandolin and the rather wonderful mandobass together for many years.

Simon Mayor and Hilary James moved into their new home in Reading around three years ago, and since then most of their recording has been the production of live albums done on location. They wanted to be able to make release‑quality recordings at home using their Digital Performer and Mac Pro system but had unfortunately been experiencing problems that were mainly, although not entirely, down to acoustics.

Cuboid Crisis

When we arrived, Simon showed us to the upstairs room where his gear was set up, and both Hugh and I immediately recognised the almost perfect cube shape of the room as being a serious problem. Their Victorian house has very high ceilings, so although the room was just about big enough, any modal problem caused by resonances relating to the distances between opposing surfaces would occur at more or less the same frequencies for both pairs of walls and the floor/ceiling. There was no acoustic treatment at all and this, combined with the large expanse of painted plaster, gave the room a very obvious coloration and an over‑lively character.

Simon had his desk set up so that he was sitting close to the edge of the room with his back to the window, and his very nice ATC SCM12 passive monitors were set up on pieces of furniture at the far side of the room, with their backs virtually against the opposite wall. These were driven from a rather old Quad 303 amplifier and Quad 33 preamp Given the distance from the monitoring seat, the ratio of reflected to direct sound was less than ideal. Simon was also using a Tascam TMD8000 console, purely for its preamps, but was considering buying dedicated mic preamps instead, because he thought he'd rarely need more than six on a session. All Simon's mixing is done using a mouse and MOTU Digital Performer software. He doesn't feel the need to use a control surface because he likes to use a lot of automation.

Potential

On arriving, the existing cuboid control room had such awful acoustics that we decided to decamp the studio to this lovely rectangular room.

We could have had a shot at improving the room layout and acoustics, but it was obvious that the room was less than ideal. Simon and Hilary also explained that they used the larger room across the hallway when rehearsing and recording because it sounded better, and they had wondered about moving the studio in there. This room, again, had a high ceiling and a varnished wooden floor, but a much more healthy, rectangular shape. This seemed a much better option, so we moved some furniture to make room for the computer desk midway along the narrow wall of the room, at the opposite end to the bay window. There were no 'proper' speaker stands, but Simon produced two narrow and solidly built sets of wooden drawers of about the right height, but which were originally designed as part of a larger unit and were open at the top — so he went off to saw some chipboard rectangles to sit on top of these to support the speakers.

To keep everything stable, we used some non‑slip matting under the drawer‑unit bases and a few more pieces beneath the chipboard tops to prevent them sliding around. This matting is available from most kitchen and DIY stores. We then placed a pair of Auralex MoPads under the speakers, with the extra foam wedges inserted so as to tilt the speakers slightly downwards, aiming the tweeters exactly at the listener's head. Once the rather heavy ATC SCM12s had been put in place, the speaker mounting arrangement seemed quite secure — although Simon said that he may still look for some suitable speaker stands. Normally we'd recommend MoPads (or the more sophisticated Primacoustic Recoil Stabilizers) when mounting speakers on shelves or on furniture such as this, but they shouldn't be necessary when mounting them on rigid metal stands, especially with stands that are filled with sand. (For stand mounting, small blobs of Blu Tak under the speaker are generally all that's needed.)

Connecting up the system was fairly easy, because Simon's audio interface is a MOTU 2408. This device's breakout box has eight analogue ins and outs, and connects via a Firewire cable to a dedicated host card that slots into the computer's motherboard. Outputs one and two from the MOTU fed the Quad preamp, and we shortened the rather long speaker cables from an excessive 13 metres down to around two metres, ensuring that both were the same length. We arranged it so that all the power came from a single distribution board, so as to reduce the risk of ground‑loop hum, before firing it all up and playing Hugh's old faithful BBC audio test CD.

Mysterious Monitoring Malaise

Paul White discusses the improvements with Simon and Hilary: despite the lively nature of the room, only four pieces of acoustic foam and a couple of strategically placed duvets made a world of difference to the sound.

To our surprise, the result was somewhat bass‑light, and on closer investigation it transpired that the left speaker was quieter than the right. It was also projecting much less low end. Our first suspect was the phono‑to‑DIN cable that connected the MOTU outputs to the Quad preamp's 'tape' inputs, but although one phono plug seemed dodgy enough to warrant us resoldering it, repeating the test revealed the same problem. Simon then found a new phono-to-DIN adaptor to substitute for the original cable — but the fault still remained. The source selector switches in the Quad preamp were somewhat intermittent, and after some cable‑swapping to try to identify where the problem was, it looked like a power‑amp fault. Hugh took the top off the amplifier and discovered that two of the PSU capacitor seals were bulging slightly. Power-supply capacitors deteriorate with age, and when they do it is best to have them replaced. We thought that these faulty capacitors could be the cause of the lack of bass in one channel: it seems that this splendid old Quad amp and preamp could use a full service back at Quad HQ.

Fortunately, Simon had another amplifier available, albeit another vintage model belonging to his hi‑fi system: an A&R Cambridge A60 model, complete with wooden case. Other than a crackly volume control, this worked fine and delivered a solid, properly balanced sound with a much better low end. For monitoring at modest levels this worked fine, but for the best results with ATC speakers (which take a lot of driving) a more powerful amplifier would provide the necessary headroom, and probably also better control of the low end: something between 100 and 200W per channel would be ideal.

Damping Down

Speakers are ideally placed on proper stands, but if you have no option but to place them on shelving or furniture, you can improvise effective mounting structures using chipboard, non‑slip rubber and Auralex MoPads.

With the basic system working, it was now time to look at the acoustics, because the room sounded extremely lively. It would have been a shame to spoil the decor of the room by permanently fixing or gluing anything to the walls, but fortunately the room was fitted with a picture rail running all the way around. After a brief discussion, Hilary cycled into town to pick up some picture‑rail hooks and nylon cord while Simon finished preparing a splendid salmon lunch.

Once we had the necessary materials, we started by fixing loops of nylon cord to some thin strips of wood, which were then glued across the backs of four Auralex pyramid foam panels, so that we could hang them like paintings using the picture‑rail hooks. Four panels wouldn't be enough for a room this size, so we decided to press a couple of duvets into service too. Duvets are not dense enough or thick enough to make effective full‑range absorbers, but a cheap winter‑weight, polyester‑filled duvet will dry up the mid range and high end quite effectively, improving not only the monitoring, but also the sound of instruments and voices recorded in the room. Again, we opted to hang the duvets from the picture rail so that they could be taken down and stored when not in use. Hilary found some spare wooden curtain-rings, and after some unsuccessful experiments with safety pins — which can't take the weight — I decided to try stitching them on using some of the nylon cord we'd used for hanging the foam panels. Fortunately, Hilary had an extra‑large darning needle, so it was just a matter of pulling the thick thread through the duvet using a pair of pliers, then tying it around a curtain ring. We found that by putting an extra bend in the picture hooks using pliers, the curtain rings would hang from them quite securely.

There was nothing unusual about our approach — we wanted to damp the mirror points at either side (the high ceiling didn't seem to be a problem) and also the two flat sections of rear wall at either side of the bay window. We needed enough damping to dry up the over‑live sound of the room but not so much as to make it unpleasantly dead for playing in. A glass‑fronted bookcase was located at the right‑hand reflection point, so we modified more picture‑rail hooks and used them to hang a single duvet from the top of the bookcase door, with one of our foam panels hanging between the bookcase and the large fireplace located halfway along the side wall. A similar foam panel and a double duvet were hung on the left wall, and two further foam panels took care of the rear wall, either side of the bay window. There seemed to be no serious bass problems, probably due in part to the natural trapping effect of the window and door, as well as the large room size and friendly dimensions, and once the foam and duvets were in place, the acoustic felt very comfortable, both for playing and mixing. The new monitor setup had excellent stereo imaging, with a solid and stable phantom centre image for centre‑panned sounds, and a well-balanced sound everywhere in the room — there were no obvious zones where the bass was too heavy or absent.

We'd also brought along a couple of 2x2‑feet Real Traps panels. These can be used to provide bass trapping in corners, but we thought they'd also make useful mini gobos, improving the separation between small instruments such as mandolins when recording. For mixing, they could be placed on the wide mantlepiece to help control reflections from the right wall. Simon was eager to try these because he'd always had to try to improvise screens between instruments.

On Reflexion

A problem in the monitoring chain that resulted in a bass‑light sound was eventually traced to the power amp's capacitors, which had deteriorated over time. It may sound bad, but a quick service should put things right!

Hilary was also very keen to improve the sound of her recorded vocals. She was using a Rode NT2 for her vocals, which she'd sensibly chosen after doing several comparative blind tests with mics at various price points, to see what worked best on her voice. For a pop shield, she was using a home‑made 'tights and coat hanger' solution, and this worked well enough.

Sonic Distribution had kindly donated a Reflexion Filter for this Studio SOS visit. The idea of this device is that the curved screen reduces the amount of sound falling on the rear and sides of the mic, as well as reducing the amount of the singer's voice getting out into the room and subsequently reflecting back into the microphone. In our experience, these work much better when the singer also has an absorber directly behind them to prevent sound bouncing off the wall, travelling over their shoulder and back into the sensitive front of the mic. In this room, all Hilary needed to do was stand with her back to one of the duvets we'd hung up, picking a place somewhere between the wall and the middle of the room but without being too close to either. Simon found a rather old and very heavy mic-stand with screw‑in legs that was ideal for supporting the weight of the Reflexion Filter, although, as usual, we rejigged the mounting hardware to get the centre of gravity in a more sensible place. Used as SE recommend, you need a mic stand with very long legs to avoid toppling, as both the mic and Reflexion Filter are on the same side of the stand, but you can use a second mic stand, screwed directly into the base of the Reflexion Filter, to support it separately, if you prefer.

Results

By the end of the afternoon, Simon and Hilary had their studio working in a much more pleasant environment than before, with more space, more light and a better sound. The wooden floor was ideal for recording acoustic instruments, while for vocal recording it would now be easy to pull a rug under the vocal mic when needed. They played a few tunes live in the room so that we could check out the subjective sound, and it seemed close to perfect for the instruments being used. Hilary also did a spot of singing, which again sounded well balanced, and not unduly influenced by the room. Best of all, every piece of acoustic treatment can be lifted down in minutes — we didn't need to drill a single hole or glue anything to the walls — which should be music to the ears of anyone recording in rented accommodation. We can't wait to hear their next studio album!