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Studio SOS: Mixes That Translate

Allan Murrell
By Paul White

This month the intrepid SOS team travel to Wigan to address Allan Murrell's recording, monitoring and mixing problems.

Allan Murrell has a very enviable studio setup made all the more attractive because it is set up in a spacious farmhouse near Wigan where he has a separate control room, a spacious live room and a smaller adjoining isolation room with a window onto the live room that can be used for recording vocals or drums. These are all repurposed from an entrance porch, dining room and living room — apparently to the dismay of his long-suffering girlfriend! Rather than go the computer route, he has based his system around a Mackie HDR24/96 24-track recorder, a Mackie D8b mixing console (with numerous plug-ins) and a pair of Mackie HR824 active monitors, backed up by a pair of Genelec 1029As. Just in case you think he's bought shares in Mackie, he also has a rack of outboard processors that includes a Lexicon MPX500 reverb, a TC Electronic M*One XL reverb and a TC-Helicon Voice One vocal processor, as well as some nice analogue boxes, including a TL Audio Ivory 2 valve compressor.

Allan Murrell.Allan Murrell.He also has a good selection of mics, including the budget Superlux drum set, an AKG D112 kick-drum mic, some Rode NT3s and (his current favourite) a Rode NTK tube mic. Though Allan set up the studio for his own use, it soon became clear that there was a demand from bands and artists in his area, so the studio is becoming increasingly commercial. To enable bands to get good results very quickly, the live room is set up with a Roland V-Drum kit (with real cymbals and often a real snare drum), two Line 6 Pods and one Line 6 Bass Pod, the latter three set up on stands with headphones for the players. There is also an acoustic drum kit for those that require or prefer it.

Allan called us in because he'd had some problems with his mixes not sounding as good on systems outside his studio, and he was also concerned that his small live room made vocals sound slightly coloured. Additionally, he wanted us to check over some mixes he was working on, as he felt he wasn't getting the best possible sound from all the tracks and wanted to see if he could get cleaner-sounding mixes. After a surprisingly uneventful trip up the M6, Technical Editor Hugh Robjohns and I found ourselves sitting in Allan's control room drinking coffee and negotiating a plate of chocolate cake — Allan had clearly read previous reports and was aware of the requirements regarding esurience displacement!

Control Room Troubleshooting

We decided to start with the large control room, which was rather unfortunately proportioned, being almost 14 feet square and a little less than half that in height. Having dimensions that are close to being equal to or multiples of each other tends to exaggerate room mode problems, though the two large windows and one door helped to act as bass traps here. Before suggesting anything, we listened to a selection of Allan's mixes and some commercial CDs through the system before deciding on a course of action. The room tended to produce a slightly muddy sound with less-than-ideal stereo imaging, and one or two bass notes really set off the room's standing waves.

Studio SOS

Part of the problem was that the Mackie monitors were standing on outrigger shelves on the IKEA computer table that formed the control centre for the studio. These were not particularly rigid shelves, and even though the speakers were standing on dense foam blocks, both Hugh and I thought the bass end could be tightened up by mounting them on proper stands. We also felt that reflections from the wall behind the monitors should be killed if at all possible, something we tested by first fixing a duvet to the wall, then adding some profiled foam sheeting when we confirmed that it did indeed help tighten up the sound, particularly the stereo imaging. As Allan had plenty of spare foam sheet, we also fixed a couple of panels to the ceiling above and slightly in front of the mixing position (using spray adhesive), to damp down reflections from the low ceiling.

Comparing the Mackie monitors with the pair of Genelec 1029As Allan had for reference, we came to the conclusion that the Genelecs were sounding rather boxy, with too much bass, while the Mackie monitors were slightly bass light in their current position well away from the back wall. Setting the rear-panel switches on the Mackies to normal for the high and low ends (rather than the middle setting for the bass switch) and leaving the speaker environment switch set to 'full space' proved to work rather well. Hugh needed to set about the 1029As with a screwdriver to move the heavily recessed DIP switches to setting three so as to introduce around 2dB of low cut starting at around 500Hz. We also moved the Mackie monitors inwards towards the support side of their shelves, to try to improve their stability, moved them forward and angled them inwards, aiming at the back of the mixing chair.

Hugh assesses Alan's Mackie and Genelec monitor sound before suggesting improvements.Hugh assesses Alan's Mackie and Genelec monitor sound before suggesting improvements.Because Allan had read one of our previous Studio SOS pieces where there had been problems with sound from Genelec 1029As reflecting off the computer monitors, he had installed more foam between his monitors and speakers. However, in this situation there was actually little risk of reflections, since the speakers were slightly in front of the monitor screens with this particular setup.

Once all these adjustments were complete, the sound was noticeably tighter, and the two sets of monitors were in closer agreement as to how the mixes should sound. A duvet was hung over the door in the side wall to damp reflections, while the curtains were drawn on the window opposite to cut down on reflections from the glass (as well as sunlight causing glare on the computer monitors). We also suggested moving the entire equipment rack back a little closer to the rear wall, but as it needed to be completely stripped down before it could be moved, we left that for Allan to try at his leisure...

Live Room Acoustic Problems

The small live room presented a different problem, as our speech immediately sounded coloured when we walked in there, even though almost all the walls and windows were covered in more of Allan's profiled foam. I guessed that part of the problem was down to the foam being fairly thin and very lightweight, with a fairly open cell structure, which meant it was probably only absorbing effectively above 500Hz or so, mopping up all the high end but leaving the lower mid-range and bass frequencies to reflect freely. Actually the large window area probably helped with the deep bass, as most of this would pass straight through, but frequencies in the 150-350Hz region were definitely dominating the room. Allan was also recording with the mic set up very close to one wall, so we suggested removing the foam from some of the window area at one end of the room and using it to double up the foam at the other end to form a well-damped corner where the singer could stand (back to the corner). We fixed up the foam in a temporary fashion, moved the mic stand, and straight away the sound was more open, with a better balance of mid-range and high frequencies.

Studio SOSWe also felt that replacing the foam on the wall opposite the window with a thicker, more dense type (three to four inches thick) would control the low mid-range even better. However, as nearly half this wall was given over to the window looking out onto the live room, this wouldn't kill any flutter echo between the two windows.

As predicted, there was some noticeable flutter echo at the opposite end of the room to the vocal corner, where we'd removed the foam, which might be a problem when recording drums, but the vocal end was fine. As Allan wanted to get better sound isolation between the big live room and the small one, we suggested that, as the house walls were very thick, he could remove the single-glazed window dividing the two rooms and replace this with a double-glazed one, set at an angle to the window opposite. This would kill the worst of the flutter echo and significantly improve the isolation. As Allan had a double-glazing engineer as a studio client, this seemed to be a very promising avenue!

We also noticed that a lot of fine dust was coming off the foam, and this turned out to be the polyurethane breaking down due to the action of sunlight. Where such foam is to be used in direct natural light, it is best to cover it with fabric or, where it is to be used in a window opening, to fix it to hardboard or MDF with the board facing the window. Painting the board black provides a professional and neat finish for anyone looking at the window from the outside.

Fixing The Mix

Allan had been working with a rather good band that clearly had Pink Floyd/Roger Waters influences and, though his mix didn't sound bad, it didn't have the punch and clarity that he wanted. My first experiment was to try the Acuma Labs Final Mix plug-in on the D8b to attempt some mastering-type processing, which involved low-ratio, low-threshold three-band compression and a touch of the inevitable 'air' EQ (gentle wide boost at 16kHz in this case).

I reset the processor's crossover frequencies to 150Hz and 5kHz so as to leave the mid-band intact and used the gain settings in the three compressor bands to fine-tune the tonal balance. This opened up the mix quite noticeably, but there were some track EQ and balance issues we felt we could improve on, so all three of us went through the mix a channel at a time and checked the quality of the basic sounds while looking at the processing Allan had used.

Studio SOS Allan Murrell.Allan felt he had got into a bit if a rut with his EQ settings and was applying some 'by habit' curves in situations where they might not be the best thing to use. Furthermore, he had used some compression and EQ while recording and, while this can be perfectly valid in some circumstances, it made it very difficult to approach the mix with a clean slate. Our suggestion was for Allan to make future recordings with flat settings and minimal compression, at least until he got a feel for what could safely be done at the recording stage.

One of the first changes was to edit the Plate reverb setting being applied to the drums via the Lexicon MPX500, primarily by reducing the bass multiplier value from 1.0 to 0.6 and increasing the pre-delay to around 60ms. This took a lot of the muddy mid-range out of the reverb, resulting in a crisper drum sound.

The first sound we felt needed improving was the fretless bass, where Allan had used some chorus, compression and EQ. The chorus sounded fine and the compression wasn't too far off, but the EQ he'd set up had a deep notch in the low mid-range, which meant there was plenty of deep bass but no real definition. Removing this dip and adding boost centred at around 250Hz immediately reinforced the woody quality of the instrument. Once the rest of the mix was brought back in, it was obvious the bass sound was sitting much better. It sounded better defined and was punchy without sounding overblown — and it could still be heard clearly with the monitors turned down, when deep bass tends to disappear.

Still at the bass end, the kick drum was also lacking definition, something we remedied by adding quite a large amount of boost centred at around 4.5kHz and balancing this with an 80Hz hump. There was also some rather muddy ringing so we invoked the channel gate and adjusted the release time until we had what we felt was a tight, punchy kick sound.

This was the first time I'd used a Mackie D8b in anger and, though the EQ sounded very musical, it seemed to need far more cut or boost to get the job done than an equivalent analogue EQ. Typically I might use 2-3dB of boost on an analogue EQ, but to fix this kick sound I found I was adding more like 10dB of boost! This is quite common with digital desk equalisers in my experience, although some of the later algorithms are a lot more analogue-like in this respect. Allan had used a dual-mic approach for the kick drum, with a D112 inside close to the beater head and a Superlux kick mic a little further out. Again, we had to EQ this second mic heavily in the 4-5kHz region to give it some attack, then we mixed it in with the main kick sound, but a few decibels lower in level, to provide a fuller and more rounded sound than the close mic could provide alone.

The snare had also been dual-miked with Shure SM57s, one mic above and another with the signal phase reversed on the bottom head. The upper mic needed some EQ boost at 6.1kHz to make it crisper, then the low head mic was boosted at 7.4kHz and brought up in level until we had a suitably convincing snare sound. Boost was also needed to freshen the hi-hats, in this case at 8kHz with a corresponding 140Hz high-pass filter to reduce the low-end leakage from other sources.

Acoustic & Electric Guitars

The 12-string acoustic guitar was peaked at 11.5kHz and dipped at 200Hz, the latter to cut boxiness from the sound, while a six-string acoustic was boosted at 10kHz to add shimmer. The compression Allan had applied to both these acoustic guitars was reduced until the gain reduction meters were showing no more than around 5dB of gain reduction, and the attack time was set in the region of 20ms to allow the attack of the sound to come through clearly.

The track also featured a flanged electric guitar that was tending to clutter up the middle frequency region of the mix, so it was thinned by notching it at 150Hz and adding a 4.5dB boost at 2.2kHz. A high-pass filter was set at 50Hz to take out unwanted low end, then the guitar rebalanced in the track. A lead guitar that was also taking up a lot of space in the mix was similarly treated, but with a 210Hz notch and a 2.2kHz peak. The result was a powerful guitar sound that didn't stomp all over the vocals.

Moving back to the percussion tracks, the Tambourine was treated to heavy boost at 5.1kHz plus low shelving cut below 150Hz, and then the digital trim control had to be backed off by about 5dB because the HF boost was causing the channel to overload on peaks. A shaker was brightened by adding a relatively narrow boost at 9.5kHz. While all the EQ settings seemed quite drastic, they were needed only because that was the nature of the digital EQ being used.

The outcome of our endeavours was a much more transparent and open-sounding mix with better-defined drums and bass, complemented by lively acoustic guitars and percussion. It was brighter than Allan's original mix, but sounded more natural and airy, and no longer required the mastering EQ we had used to 'polish' the original version. The last job was to try to maximise the level of the mix so that it would sound loud when compared with commercial CDs, a job we attempted using the Final Mix software by setting the compressors to an infinite ratio and fast attack time to act as limiters, and also engaging the soft-clipping function. This bought us a noticeable amount of extra level, but wasn't as intuitive to set up, or as effective, as dedicated mastering software/hardware with a separate limiter.

Mixing Multitrack Drums

Allan also brought out a multitrack recording of an acoustic drum kit which sounded a little unnatural, partly because of the way the kit was tuned and played, but also because he'd EQ'd the toms to remove what he considered was excessive high end, presumably to minimise cymbal spill. Though most of the energy in a tom resides between 100Hz and 250Hz, the high end needs to be there to preserve stick definition, so we restored the missing high end and also beefed up the kick drum at 80Hz and 4kHz to give it depth and attack. Apparently the drummer wanted a ringy piccolo snare sound, but this wasn't really in the character of the drum. Nevertheless, by cranking up the mid-range boost, then sweeping it between 2kHz and 4kHz, we found a sweet spot that improved the sound. Once located, the boost was pulled back to a more practical level.

It proved to be impossible to gate the toms (to try to clean up the mix a little) because of excessive spill from the snare which caused false triggering. This seemed very odd given that the tom mics were apparently mounted just over the tom head rims, and implied that either the drummer didn't hit the toms very hard at all (unlikely!), or that they had been recorded with some compression in an attempt to create a fatter sound. Once again, this shows that it is often better to record the original signal raw, then apply gating and compression during the mix.

The kit had been recorded with stereo overhead mics, and Allan had taken the low end out of these during recording. All they needed was a bit of high-end encouragement to lift the cymbals out, something easily achieved using boost in the 6-8kHz region. However, while this approach was fine for the intended purpose, it also meant that there was no possibility of using the overheads to form the basis of a complete kit sound, with the close mics then being added for extra definition, because the low end of the drums had effectively been EQ'd out. In other words, the mixing options had been severely limited with no real gains — another example of why it usually pays to record flat and with minimal compression, to keep all options open.

Allan had also gated the snare-drum mics quite hard, which affected the attack and resonance very audibly. The overall sound improved considerably when the gate range was set to around 10dB rather than infinity. This allowed a low level of spill to survive, which seemed to help the overall kit sound gel with the overheads, and it also improved the attack of the drums because some of the original transient could still be heard even though the gate took a short time to open fully.

In A Nutshell

The room problems we encountered were typical of those experienced by many project studio owners, and again we demonstrated that the worst of these problems could be improved at a relatively low cost. However, the control room still had a somewhat uneven bass response, largely due to its unfortunate geometry, so we suggested Allan fit two foam corner bass traps to each of the rear corners, in addition to finding a tidier and more permanent solution to the layer of foam and duvets we'd fixed to his front wall. We also felt that some one-metre-high speaker stands, ideally filled with sand, would tighten up the bass sound further.

Once the monitoring was sorted out, the reasons for the mixing problems became more evident, and it transpired that Allan had been perhaps too enthusiastic with his EQ and compression settings during recording, which had forced him into a bit of a corner when mixing. In a lot of cases, Allan had also been applying (almost as a habit) small amounts of lower mid-range cut at similar frequencies to try to reduce the perceived mid-range clutter in his mixes, rather than using the EQ to bring out the important elements of each source individually.

During mixing, we tended to use less compression than Allan had (over-compression can rob a sound of punch and clarity) and our final EQ settings were determined entirely by ear, simply by sweeping a parametric EQ across the frequency range while set at full boost to determine the best frequencies to cut or boost. Once these key frequencies have been identified, the cut/boost and bandwidth can also be adjusted by ear to give the best subjective sound. We also stressed the importance of making the final EQ adjustments with all the tracks playing, as what sounds great in isolation might sound quite wrong when the whole mix is up.

As a rule, EQ boost should be as broad as possible for a natural sound, though, in the case of drums and percussion, you can sometimes get a musically useful effect by making it narrower. EQ cuts on the other hand should be made as narrow as possible while still getting the job done, so that you're not taking anything more away from the sound than you need to.

On an artistic level, we also pushed the drums and vocals a little further forwards in the mix to get a more modern sound, while keeping any 'thickening' sounds further back in the mix to avoid congestion. A lot of modern mixes have most of their energy in the vocal, drums and bass parts, with everything else sitting lower in the mix, so choice of sound rather than sheer volume allows those parts to remain audible and distinct.

 Some Auto-Tune Tips 
 Allan also mentioned that, although he had the Auto-Tune plug-in for the D8b, he'd never really got the hang of using it, so we called up a vocal track, established its key by playing along with a guitar, and set about adjusting the controls after setting the key input in Auto-Tune's plug-in window. The most important control is the one that sets the speed at which the pitch is corrected, and once I'd figured out that this moved the opposite way from its VST plug-in counterpart (fastest correction when fully down), it was easy. The most natural correction was achieved by setting the correction speed slider about a third of the way from its top end (slowest position) where the pitch-correction display confirmed that corrections were only being made on sustained notes and that natural pitch variations were being allowed through intact. Allan was quite pleased to see this working so well as he had worried that it would sound unnatural. 
Published July 2003