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Studio SOS: Peter Brooks

Optimising A Loft Studio
By Hugh Robjohns & Paul White

Peter’s studio, after the major refurbishment but before the SOS team came to add their magic touch. To the right, you can see the tiny access door.Peter’s studio, after the major refurbishment but before the SOS team came to add their magic touch. To the right, you can see the tiny access door.

Team SOS travel to Sheffield, to help one man in his quest to realise his lofty studio ambitions.

Peter Brooks called us for advice during the planning stages of his new studio construction, and then invited us to come and help him optimise its operation once he’d finished the building work. Originally the studio was a disused loft space in Peter’s 200-year-old Yorkshire farm building, and was accessible only via a hatch in the floor. His building project included blocking the hatch, installing a new floor, and having a (low) doorway made to provide access from one of the adjoining rooms. The walls were tanked against damp and lined with insulation board, a skylight was fitted, and new power trunking installed. Overall the finished space looked very stylish, but its shape, size, and very thick external walls suggested that there might be some acoustic problems that would need addressing but which couldn’t be solved entirely by the use of mid-/high-frequency foam panel absorbers.

The floor area of the studio was around 2.3 x 3.5 metres, and the ceiling, following the profile of the roof, sloped upwards towards a fairly high back wall. Nothing was quite square or parallel, and the back wall was about a foot narrower than the front wall. All four walls and the sloping ceiling were painted plaster, with one side wall being solid stone and the others plasterboard on studs. The floor was a wooden laminate, and so the room exhibited some very obvious flutter echoes as well as being quite bright and lively overall.

Peter had his desk set up so that his SE Electronics Egg monitors faced down the length of the room, which is always optimal in smaller spaces. This placed the tall wall behind him when mixing, and the desk was set up under the low end of the ceiling slope, meaning that ceiling reflections from the monitors would tend to be thrown to the back of the room rather than into the listening area.

The loft space as it originally was! At the bottom of the picture, you can see the (since sealed) hatch in the floor.The loft space as it originally was! At the bottom of the picture, you can see the (since sealed) hatch in the floor.Peter’s equipment setup was very streamlined, comprising a Mac Pro computer (located in the adjoining room to keep the fan and drive noise out of the studio) with two LCD screens, a Focusrite Saffire Pro 40 audio interface connected via Firewire, the SE Egg monitors and their external amp pack, and a Novation Launchkey 61 USB-MIDI keyboard. The Eggs were set up on Samson monopole stands at a sensible height, although I would have preferred something more rigid. Peter also had a good selection of mics, including a couple of SE 4400As plus three Reflexion Filters.

Test Match

The first thing we did — after the obligatory coffee and Hobnobs — was to dig out Hugh’s test disc to start assessing the sound in the room. Hugh started by checking the monitors to make sure the left and right channels were the correct way around and that they were in phase, and then listened to some speech recordings in mono, to check the stability and precision of the phantom centre image (this is a good indicator of early reflection problems). We then moved on to playing a stepped chromatic bass scale test to highlight the inevitable room-mode problems. Pleasingly, thanks to the unusual room shape, this test revealed only a fairly benign broad bass hump caused by room modes, and we were fortunate in not having any serious narrow peaks or dips. So there were no missing or strongly emphasised notes, just a warm ‘blooming’ around the lowest octave. There was also the expected bass null right at the centre of the room, but fortunately the mixing position was well forward of that dead zone that Hugh and I have nicknamed ‘the spherical Bermuda Triangle of death’.

Foam On The Range

As is invariably the case, the bare walls needed some ‘standard’ acoustic treatment to tame the mid- and high-frequency reflections, so we added a few Universal Acoustics tiles to the Auralex tiles that Peter already had available. Four of our 600mm-square tiles were burgundy and a pretty good colour match for Peter’s chair, so we used these along the front wall behind the speakers and computer screens, covering the area between the power trunking and ceiling.

The foam around the back of the studio not only helped to tame early reflections from the monitors; it also provided a  ‘dry’ area for vocal and instrument recording.The foam around the back of the studio not only helped to tame early reflections from the monitors; it also provided a ‘dry’ area for vocal and instrument recording.Fitting these entailed trimming the bottom edges off the tiles and also taking a little off the sides of the outer two, as the wall was just a little shorter than the length of four tiles. The tidiest way to cut foam is with a bandsaw or an electric carving knife, but having neither to hand we used a serrated kitchen bread knife, which gave a fairly clean edge. It’s best to start the cut carefully on the top surface, which leaves a neat finish, as the back of the cut can get a little ragged. To allow continued access to the removable top section of the trunking, we left the bottom third of each tile unglued so that they could be lifted out of the way to give access without stressing the rest of the glued panel. Peter was happy for us to glue the tiles directly to the walls as they were to be a permanent fixture, and he didn’t want to put any nails or screws through the plasterboard for fear of damaging the waterproof tanking.

The foam that was to be mounted behind the speakers had first to be cut in order to fit the space.The foam that was to be mounted behind the speakers had first to be cut in order to fit the space.The tall back wall was an obvious source of strong reflections, so we used three 600 x 1200 mm Auralex panels, spaced slightly apart at around head height (when standing). These would also double up to create a dead back wall for recording vocals, while the sE Reflexion filter would provide further cover for the rear and sides of the mic. We used the remaining panels (one 600 x 1200 mm panel and three measuring 600 x 600 mm) on the side walls to cover the mirror points at the front of the room, and also to break up the flutter echoes at the back. The entrance door’s placement meant that one of these had to be a little higher than optimal, but the general liveliness of the room was gone, with the overall acoustic now feeling much more controlled.

ARC De Triomphe

Of course, foam panels do very little at bass frequencies, especially the thinner 50mm types we were using, so we still had the bass humps to deal with. Dips and humps are undesirable as they can lead you to make unsound EQ and balance decisions. Fortunately, those very accommodating people at IK Multimedia donated an ARC 2 room-correction system for us to use on Studio SOS projects, along with a few serial numbers for the necessary plug-in. The ARC 2 system includes an omnidirectional measurement mic (which must be pointed upwards), the stand-alone ARC measurement software, and a cross-platform plug-in that applies the necessary EQ correction curve based on the room measurements.

Peter Brooks at work in his revamped studio.Peter Brooks at work in his revamped studio.When we set up the system to start taking room measurements we noticed that the mic output was coming back through the monitors, and this turned out to be because of a latency-free monitoring setup in the Focusrite Saffire interface’s internal DSP mixer. However, when we tried to reconfigure it, it demanded a software update, which took a few minutes to sort out as Peter hadn’t yet set up his Mac’s Internet connection. After five minutes filling in forms and entering passwords we were able to download the latest mixer software for the Saffire interface, as well as the bundled Focusrite Midnight plug-ins and various other goodies. We also needed to authorise and register the installed software, all of which takes up more time than you might expect.

For Good Measure

The ARC system requires a minimum of seven measurements to be taken at and around the mixing position, with any off-centre measurements being done in symmetrical left-right pairs. We took two pairs of off-centre measurements at and just slightly behind the mixing position, along with three measurements along the centre line, taken at, in front of, and behind the listening position. The software takes you through each step, including selecting the desired I/O ports on the audio interface, and refuses to move on to the next step until the test signal level is optimised in the monitors and through the mic preamp. Once all the necessary measurements have been taken the software integrates them and comes up with a stereo correction curve file, which can be loaded into a plug-in that you insert in the DAW’s main mix bus or (preferably) the monitoring bus. Naturally, if you use it in the main mix bus, the plug-in must be removed or bypassed when bouncing any final mixes, otherwise the room-correction EQ curve will be embedded into the mix itself!

Title LightIn common with most such software, the majority of adjustments involve pulling down humps rather than boosting elsewhere, because adding any significant boost to dips in the response can really eat up headroom in the amplifiers and speakers. In the case of Peter’s room, the majority of the processing was used to tame a single, broad peak in the bottom octave, and running through some of Hugh’s test tracks again, both with and without the processing active, showed that the ARC 2 system gave us a noticeably tighter and better-controlled low end. I’m always wary of using EQ to address room-mode problems, as these exist in the time domain while EQ tackles only the frequency domain. Having said that, when you’ve done all that is practical using acoustic treatment, such systems can still bring about a significant improvement, even though their result is only valid for your normal mixing position.

Ceiling Groovy

Peter uses Logic Pro 9, so after we’d sorted out the acoustic issues to get a pretty decent sound in the room and from the monitors, I set about creating a Logic Template song, which Peter could use as a starting point for his recording projects. It contained eight audio and eight software instrument tracks, with a general-purpose reverb and a delay on two post-fader aux sends, the ARC plug-in installed in the main mix bus insert point, and screen sets to utilise both his monitors effectively. Templates are a great way to save time, and by including the ARC plug-in as part of the template there was no risk of anyone forgetting to use it. Our final task was to go through some preliminary recordings Peter had made and offer a little general advice on mixing and the types of Logic plug-ins that might be most useful to achieve the results he was after.

And so, after thanking Peter for the bacon sandwiches and Hob Nobs, we headed back out to that joy that is the M1 motorway.

Reader Reaction

Peter Brooks: “Overall I was very pleased with the studio, having followed the advice around the structural aspects and finally having completed the work, set up the Mac Pro running Logic 9, and started using it.

“The room was overly bright though and, as it’s only about 2.5 x 3.5 m with a roof that slopes from about 1.5m at one end up to about 3.4m at the other end, had quite noticeable issues with uneven bass response. This is where the SOS team’s visit really helped. Application of a good number of acoustic foam panels at the key points in relation to the mixing position quietened the room down significantly, and has made it better not only for mixing, but also much more pleasant for playing in. An unexpected bonus was the IK Multimedia Acoustic Room Correction (ARC 2) system that SOS brought along and used to analyse the acoustic response within the room, and produce a correction plug-in which sits in the last slot of my output chain. This has made a massive difference and tamed the bass response to a sensible and, more importantly, even, level.

“Over the now-standard bacon sandwiches and Hob Nobs, much other general advice was given, along with a useful template being setup in Logic for me by Paul. I can’t thank Paul and Hugh enough for their visit — I now have a studio that’s as good as it could possibly be, and had a very enjoyable and informative day with two of the country’s experts in the recording field.”

Published November 2014