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Studio SOS: Stourbridge Community Centre

Solving Low-end Problems
By Hugh Robjohns & Paul White

The control room is of a reasonable size, but the identical dimensions of the height and width bode ill for the low-end response.The control room is of a reasonable size, but the identical dimensions of the height and width bode ill for the low-end response.

The SOS team travel to a Stourbridge community centre to solve some low-end problems and build some speaker stands.

Nic and Chris run their studio, Raindance Music, from two rooms at the back of the Christian Centre in Stourbridge, and the guys called us in because the low end of their mixes wasn’t translating to the outside world as well as they would have liked. As we live a relatively short distance from Stourbridge, we made a preliminary visit to establish the seriousness of the problem and to think about possible solutions. Nic and Chris made sure they had plenty of coffee and chocolate Hob Nobs on hand to keep us going, but it didn’t take long to establish that the bass end was indeed quite uneven!

Installed on the building’s first floor, the control room was reached by descending a few steps at the back of the room from the stairwell, while a compact live-room space was located almost immediately below on the ground floor. The control room had a sloping wall at the monitor end, which was directly under the building’s roof, and although the maximum ceiling height (to the suspended ceiling) was quite high at around 2.8 metres, the width of the room was almost exactly the same — never an ideal situation from a room-modes point of view. The length of the room, from the door up to the point where the ceiling starts to angle downwards, was 3.6 metres, with around a further three metres of essentially wasted and difficult-to-use space beneath the sloping ceiling.

The room had some basic acoustic treatment installed, comprising some mid/high absorption in the form of a few 20mm-thick high-density mineral-wool panels covered in fabric, but these weren’t anywhere near thick enough to help with the room’s low-end issues, and there wasn’t very much of it anyway. There was one 600 x 600 mm panel each side of the monitoring position, and a 1200 x 600 mm panel mounted on the sloping wall directly above the mixer. Although the entire right-hand wall was covered in carpet, this was actually glued straight to the plasterboard wall, which wasn’t doing much for anything other than the extreme high end.

Something else that caught my attention was that the monitors were set up on DIY wooden stands made from three pieces of 50 x 150 mm timber screwed together to form a solid post, with square plywood panels fixed to the top and bottom as floor and speaker plates. Despite the use of thin self-adhesive foam sheets on the floor and speaker sides of these panels, the whole arrangement was a little wobbly and unstable, and would benefit from improvement.

In terms of control-room equipment, their system is based around a Mac Pro running Logic Pro 9, with a Tascam DM4800 digital mixer used mainly for signal routing, monitoring and patching in hardware preamps and effects processors. The monitoring was courtesy of a pair of nice PMC TB2 passive monitors that which were originally driven by a Hafler amplifier. However, when that recently failed they switched to a hefty Parasound A21 power amplifier (equivalent in power to the legendary Bryston 4B), which they picked up second-hand. Nic and Chris apparently noticed a worthwhile improvement in control and precision (passive PMCs certainly do seem to respond well to more power!).

Rolls of loft insulation make excellent bass traps, provided you’ve got somewhere to put them — like the unused space between a desk and an angled ceiling!Rolls of loft insulation make excellent bass traps, provided you’ve got somewhere to put them — like the unused space between a desk and an angled ceiling!The live-room monitoring was provided via a Behringer Powerplay P16-I input module, mounted above an eMagic AMT8 MIDI interface, the Parasound amp, and a Technics CD player in a fixed rack under the right-hand side of the desk. A wheeled flightcase rack on the left-hand side contained all the really nice toys, and was designed to be easily removed for location recording duties. At the top, an SSL Xlogic Alphalink MADI-AX interface communicated with the Tascam digital console, with an SPL Stereo Vitalizer, Drawmer 1969 valve preamp/compressor, and an Empirical Labs EL8-X Distressor sitting below. Further mic preamps included an Apogee Mini Me two-channel preamp and A-D converter, a Neve 4081 quad-channel and 1073 DPA two-channel preamps, an API 3124 quad-channel preamp, and a PreSonus DigiMax FS eight-channel preamp/ADAT interface.

There’s A Trap For That...

Listening to some familiar music and a sequence of bass tones through the monitors, there were quite substantial audible bumps and dips in the low-end response, along with a general sense of the bass not sounding as tight as it should. The stereo imaging was also not as sharply defined as I’d expect from such good monitor speakers, all of which broadly confirmed the problems Chris and Nic had been complaining about. My initial diagnosis was that some bass trapping would be needed, the mid/high absorbers would need improving, and the speakers would need better supports. However, whereas installing adequate bass trapping is often a major problem in most project studios because of insufficient space, the part of the control room extending under the sloping roof behind the Tascam desk seemed an obvious and very convenient place to install a considerable amount of bass trapping. If really necessary, there was also further empty space above the ceiling tiles that could be used as well (it’s almost impossible to install too much bass trapping!).

Placing the PMC monitors on a set of IsoAcoustics isolation platforms on the desk helped the low-end response tremendously, but meant that the speakers were a little too close to the listening position for comfort.Placing the PMC monitors on a set of IsoAcoustics isolation platforms on the desk helped the low-end response tremendously, but meant that the speakers were a little too close to the listening position for comfort.I suggested that Hugh and I return at a later date to help with the mid/high absorbers and monitor stands, and to generally fine-tune the room as best we could, but in the meantime we recommended that Nic and Chris try filling the angled void behind the mixing desk with as many rolls of loft insulation as they could cram in there. This is a very cost-effective form of bass trapping, and is a very easy (and clean) job because the rolls can be left in their original plastic packaging. This arrangement forms a kind of damped membrane LF absorber that previous experience has shown works pretty well for budget bass-trapping applications, as long as you have the necessary space (which is considerable!).

Second Coming

Sure enough, when we returned a few weeks later, Nic and Chris had installed 12 rolls of insulation into the space behind the mixer. The guys were quite enthusiastic about the improvement such a simple alteration had already made, and when we fired up Hugh’s test CD it was instantly obvious that the bass response in the room was massively more even than before. However, the sound still lacked the tightness that the PMC TB2s should have been able to deliver, and our suspicions fell on the speaker stands, so our first test was to move the speakers onto the desk (a thick kitchen worktop supported on trestle legs), and put them on IsoAcoustics isolation supports, which SCV London kindly donated.

We constructed the ISO L8R130 supports initially with the supplied eight-inch columns, and this simple change actually made quite a dramatic improvement, but everyone thought the speakers were a bit too close to the listening position, so we suggested we dismantle the original wooden speaker stands and re-build them to be more stable — again using the IsoAcoustic isolation supports, but this time fitted with the supplied three-inch uprights. After a bit of fiddling around behind the desk to extract the speaker stands from the mass of cabling that inevitably forms in dark corners, we moved out to the car park with a saw, a tape-measure, and a box of screws...

Paul and Nic modifying one of the two wooden speaker stands.Paul and Nic modifying one of the two wooden speaker stands.

Stand & Deliver

A three-point support is always the most stable, so some 75 x 50mm timber was procured with the intention of using that to form T-shaped bases to the stands. The rebuild involved removing the plywood top and bottom plates and cutting about eight inches off the length of the three-plank pillars. We then dismantled the pillars so that a further section could be cut off the centre piece to allow a forward-facing foot to be inserted, made from the 75 x 50mm timber. Another length of the same timber was fixed across the rear of the reassembled tri-pillar to form two sideways-facing feet. Wood screws were fixed into the bottom of each of these three feet, protruding just a few millimetres, to provide three wobble-free points of contact with the floor. To complete the makeover, the top platform was halved in size in order to take the compact IsoAcoustics isolation mount.

After more crawling around under the desk to re-install the renewed speaker stands, and with the PMC speakers reinstated, the stepped tone test from Hugh’s CD confirmed that the bass response exhibited only the tiniest of mild bumps and dips, and the bass end was much tighter and better-controlled than when the speakers were on the original stands. The remaining very mild bass response bumps and dips could be improved by installing even more bass trapping, and there was still some space behind the desk for another two or three rolls of loft insulation, so that was added to Chris and Nic’s to-do list. Nic said he might also put more bags of insulation in the roof space because Hugh suggested this might make a further useful improvement. This very simple bass-trapping solution is extremely easy and cost-effective to try, and you can still sell the stuff ‘as new’ if it’s no longer needed, as it can stay in its retail bags!

With the low end improved by bass trapping, some Auralex acoustic foam was deployed to tame some of the high-frequency reflections.With the low end improved by bass trapping, some Auralex acoustic foam was deployed to tame some of the high-frequency reflections.

Foam Calls

Time, next, to think about the mids and highs. Auralex had kindly donated to the project a box of six 600 x 600mm panels of 100mm (four-inch) Studiofoam Wedge acoustic foam tiles, and we decided that the most effective way to use these would be to put two at either side of the listening position in the ‘mirror’ points, and two more above the mixer in place of the thin rockwool panel already up there. One of the mirror-point panels needed to be over the side window, so Nic suggested that we glue our treatment to his now redundant 600 x 1200mm mineral-wool panel so that it could be leaned in the window recess when needed. We settled on one of our Auralex panels glued it to the centre of his 600 x 1200mm panel in the window, which would put it at around head height for anyone seated in the mixing chair, and to glue the other one for that side of the room directly onto the lightweight panel that was already hanging on the wall. For the opposite wall we glued two foam squares directly to the existing carpet, and for the space above the mixer we glued the last two Auralex foam panels directly to the ceiling tiles.

Playing some of Hugh’s test tracks revealed a much clearer stereo image, with a good sense of focus and a stable phantom centre image. Switching to mono placed the image directly between the speakers, as a narrow, sharp image, just as it should. Both Nic and Chris commented immediately on the improvement in overall clarity, and the increased ability to hear into the mix.

Voilà! The combination of foam and insulation absorbers, and the incorporation of IsoAcoustics absorbers into the speaker stands, yielded a significantly more accurate sound at the listening position. One of the equipment racks was also relocated to the left of the desk, where it now works as a handy keyboard and mouse stand.Voilà! The combination of foam and insulation absorbers, and the incorporation of IsoAcoustics absorbers into the speaker stands, yielded a significantly more accurate sound at the listening position. One of the equipment racks was also relocated to the left of the desk, where it now works as a handy keyboard and mouse stand.

Baby Got Rack

With the basic acoustic treatment usefully improved, we looked at other areas where we could enhance things further. The desk area around the mixer was a little congested, so Hugh and I suggested that the outboard equipment rack could be moved to the right of the desk, where its top would be a handy place to put the Mac keyboard and mouse. This would also leave more space to place Chris’s Nord Stage keyboard by the window where it would be more accessible, instead of tucked under the desk as it was previously. A little rejigging of the cables and this was done, leaving the desk area feeling far less cluttered.

At this stage we broke for a lunch of fish and (orange) battered chips (yes, really — it’s a West Midlands delicacy!). Afterwards we went back to play some of the mixes Nic and Chris had been working on. Nic said that the improved monitoring accuracy was showing up some elements in his mixes that would merit further adjustment, but that should mean that the low end would translate better when the mixes left the studio. Chris agreed, so after tinkering with their mixes for a while, Hugh and I agreed that it was time to leave Nic and Chris to it.

Raindance Music

Raindance Music (www.raindance-music.com) was formed nearly 15 years ago as a ‘one day a week’ project. Inspired by Clyde Sandry, the then senior pastor of Amblecote Christian Centre, Nic and Chris pooled knowledge and resources and set up in a spare room at the centre, which was already established in serving various sectors of the local community.

Initially catering for the recording needs of people from the immediate area, they were soon gaining a reputation for good-quality work which spread to the wider musical community. Fifteen years on, and in another part of the building, it’s now a full-time operation offering clients a full production service that sees songwriters, bands and artists from all over the country, as well as some from as far as Northern Ireland, Holland and Switzerland.

Reader Reaction

Nic (left) and Chris (right).Nic (left) and Chris (right).“We had a very enjoyable day with Paul and Hugh. Their experience and expertise highlighted and then solved the problems we were having, resulting in a much more accurate listening/mixing environment.”

Published August 2015