The Studio SOS team sort out some acoustic problems, streamline a studio setup and brush up their drum & bass production skills!
Like so many Sound On Sound readers, Michael Coghlan doesn't have the luxury of a dedicated studio space. His recording setup is tucked away in the corner of a basement room that doubles as his office and as a guest bedroom. The room is around 2.5 x 3.5 metres and perhaps two metres high, with built‑in shelving and cupboards at one end and a patio door opening onto a small basement yard at the other.
In addition to a small desk housing Michael's PC/Cubase recording setup, there is another fairly long bench unit for his DJ decks and mixer, which, along with a bed-settee, leaves little room for manoeuvre. Michael had read many of our previous Studio SOS articles and fully understood that, in an ideal world, the monitors would face down the length of the room, but given the other functions of the room and the size of the furniture, this simply wouldn't be practical.
Coming from a DJ background, Michael's passion is drum & bass. His arrangements and choices of sounds were impressive and showed a DJ's appreciation of where the tracks should build and where breakdowns were needed, but he was having problems producing consistent mixes, and was burning countless CDs as he went around the loop of listening to his tracks on different systems, then going back and tweaking the mixes, burning new test discs, and so on. He also needed some tips on achieving adequate loudness without limiting his mixes to death.
Almost as soon as we arrived, Michael produced several packets of chocolate Hob Nobs and a large tin of Foxes biscuits, which he'd assumed from previous Studio SOS articles were some kind of prerequisite. We did nothing to dispel this notion! During tea and biscuits, Michael outlined his problems and the limitations he had relating to positioning his gear. He also said he'd appreciate some advice on reducing sound leakage into the rest of the house, as he often tends to work into the night.
Our first step was to play some test material over the system, which is based around a PC running Cubase 4. The PC is fitted with a Terratec interface, which connected to a Soundcraft Spirit Folio mixer and on to an Alesis power amp and a pair of Alesis Monitor One Mk II passive speakers, supported on rather wobbly metal stands. Michael had also integrated his DJ system, which includes two vinyl decks, two CD decks and a DJ mixer. These also fed into the Spirit mixer, and the tape output of the mixer was connected to the input of his audio interface. He often recorded material from his DJ system into Adobe Audition for editing before importing it to Cubase, so his wiring was rather convoluted. A Line 6 KB37 was set up as a controller keyboard connected via USB (though its audio facilities were not being used), while an SM58 was set up on a stand at the far end of the room for recording vocals.
With the speakers firing across the room and the right‑hand speaker backed into a corner, we expected some serious bass problems, but playing some test material via the turntables showed fewer violent fluctuations in level than we'd expected. There was a hump at around the port frequency of the speakers and another in the 150 to 200 Hz range, giving the bass something of a 'scooped' character, but it was nowhere near as bad as we'd expected.
Our first tweak was to move the speakers forward slightly, so that the distance of the right speaker from the wall behind it would be greater than the distance from the side wall. This helped a little, but the general bass character remained the same. The stereo imaging was also a little blurry, and such bass as we did have didn't sound as tight and well‑controlled as we'd have liked, so some acoustic treatment was definitely in order.
Welsh company Silent Peaks had given us some of their speaker platforms to use on our Studio SOS missions, these comprising a steel sheet on top of a foam block, with a heavy, thick neoprene slab atop the steel plate. The idea is that the foam helps discourage vibrations from the speakers getting into the stands, while the metal and neoprene platform adds mass and stability to the speakers. We put these on top of the existing stands (which we recommended replacing with something more rigid) and repeated our listening tests. These revealed a worthwhile tightening of the low end, which now also seemed a little more even. A simple touch test revealed that the Silent Peaks isolators were working very well, with no vibration now being felt on the stand platforms.
There was little point in trying to put acoustic foam at the side 'mirror points', as the right‑hand spot was occupied by the patio door, with a heavy curtain in front of it, and the left wall was at the far end of the room was occupied by shelving and cupboards, which would provide some useful scattering. However, we felt that the wall behind the speakers would benefit from some treatment, as would the section of wall to the immediate right, between the corner and the beginning of the window.
The Alesis speakers have rear porting, so we reasoned that ensuring there was thick foam behind these could only help smooth the bass response further. We also thought that a ceiling panel would be useful to kill reflections from the relatively low ceiling. Fortunately, Michael didn't mind us sticking acoustic foam directly to the walls and ceiling, which makes a neater job than simply hanging the panels, and he also provided a serrated bread‑knife so that we could cut a couple of panels into two to fit around the corner.
We had a few square, two‑foot panels of Vicoustic foam left over from a previous job, and as we didn't really have space to fit the 2 x 4‑foot panels that Auralex usually supply for our Studio SOS adventures, we used the Vicoustic panels instead. These particular panels have a flat surface rather than a carved profile, making them more effective at absorbing lower frequencies than a profiled panel of the same thickness.
Hugh and I fixed the panels, while Michael did the important job of boiling the kettle, then out came the test CD and we crossed our fingers, hoping we'd hear some improvement. We let Michael make that call (in case glue fumes had affected our judgement!), and the music had only being playing for half or minute when he pronounced that the bass was not only tighter‑sounding but also seemed more punchy, with improved mid-range and HF clarity. Stereo panning showed up more clearly, too, and although the low end still wasn't entirely flat, there were no really strong bumps or dips. Hugh was impressed by the performance of these monitors, considering their low cost.
Having done what we could with the acoustics from the perspective of the listening position, we turned our attention to the recording chain, as Michael was having problems with hiss when recording vocals. The SM58 was plugged into the DJ mixer, and from there to the Spirit mixer and eventually to an input on the Terratec.
Clearly, the tortuous signal path and less‑than‑optimal gain structure was producing a significant level of hiss. However, as the Line 6 KB37 can double as an audio interface and has its own quite reasonable mic preamps, we reckoned that if we could get this to work as the interface for Cubase, Michael could plug his mic directly into that, which would make recording much easier and, hopefully, much less hissy. He could also use the KB37's output to feed his Alesis power amp directly for monitoring, which would mean he would have a volume control on the desk in front of him, rather than having to lean over to reach the Folio mixer or the power amp.
Getting the KB37 up and running necessitated Michael registering with Line 6, via their web site, and downloading their Monkey software, which checks the connected hardware and finds the necessary driver downloads. Once the latest software was installed and the computer restarted, the Line 6 KB37 was selected as the active audio device, and we were in business. A test recording using the SM58 plugged directly into the KB37 gave decent results, as long as the mic gain wasn't turned to maximum, at which point some hiss returned.
We explained the concept of leaving plenty of headroom by setting the gains to get the meters reading about half full‑scale, and although there was still an audible low‑level hiss when recording quiet spoken word, it was low enough not to be a problem, and Michael pronounced that it sounded much cleaner than anything he'd achieved before. The fact that there was now a local monitor-level control, as well as a headphone feed (again built into the KB37), was also much appreciated.
Hugh then connected the DJ mixer to the line inputs of the KB37 so that Michael could record vinyl, or other material needed to create loops, directly into Cubase, without having to re‑patch anything. Reconfiguring the studio in this way meant that the Spirit Folio had become completely superfluous in the system, leaving Michael wondering what to do with his long‑serving and trusty console!
To create a drier vocal recording environment, we suggested hanging a duvet from a wooden beam, which was conveniently placed behind where the singer would normally stand. Even more conveniently, there were already nails in the beam where we could hang loops of string. We folded a polyester duvet and then tied string loops to the corners so that it could be hung from the nails. It looked like one of Michael's kids would be having a cold night!
This arrangement did indeed help to clarify the vocal sound, and it also reduced the level of computer drive and fan noise getting into the vocal mic.
Although Michael's computer was built specifically for musical applications, it's a few years old and is starting to puff and pant a bit on some of his more demanding mixes. He'd configured the system for 16‑bit recording, which makes setting recording levels much trickier than it needs to be. When we switched it to 24‑bit, however, some of his songs pushed it over the edge.
Our solution to this was twofold. One was to set a low‑ish buffer size (128 or 256 samples) when recording, to minimise latency, and a higher one for mixing (typically 1024 samples), when latency is less of an issue.
Michael often uses multiple layers to create his big and brash bass sounds, and this places quite a load on the CPU, so the other solution was to use the 'track freeze' function to convert CPU‑hungry VST instrument tracks into temporary audio files. As neither Hugh nor I use Cubase on a regular basis, it took a while to find the elusive Freeze button. Michael eventually found it (hit the F11 key) using a Google search, after the manual ran us around in circles without giving us an answer. Freezing just his bass tracks dropped the CPU load by around 50 percent, and the computer seemed far happier.
Our last practical bit of PC advice was to put a USB hub around the back of the computer, as the Cubase dongle was currently plugged into the front of the computer where it could easily be kicked and damaged.
Now, about those big, loud sounds. Michael had read about parallel compression and understood the principle, but the Cubase compressor seemed just too polite, even when set to really pile on the gain reduction. I suggested he download the free Listen Mic Compressor from the SSL web site, as that is really vicious and can work very well for parallel processing. A few minutes later, we had it loaded up and tried using it to beef up his drum sounds. It doesn't have a lot of low end but adds plenty of lower‑mid angst just where it is needed. Result! I can see that working well for Michael in the near future.
To get his mixes to compete with commercial tracks on the loudness scale, Michael had used a Waves L2 limiter over the stereo mix, set to give around 12dB of gain reduction on peaks. He combined this with some overall peaking EQ at 10kHz, to add some presence to the mix.
While this certainly made the mix sound loud, the heavy limiting robbed the drum hits of their dynamics and created a slightly fatiguing sound, so we tried the familiar EQ‑compressor‑limiter combination, using a shelving EQ at around 8kHz to add the airy highs, followed by a 1.25:1 compressor with the threshold lowered until we had around 4dB of gain reduction. The limiter was then adjusted to trim only 4dB or so off the peaks, which left us with a mix that was still loud but had a greater sense of dynamics, and without being so aggressively fatiguing.
The final issue related to noise leakage into the rest of the house. One option would be for him to look at the Focusrite VRM box, which emulates the sound of various studio monitors over headphones and is great for late‑night working. The other practical improvement would involve adding mass to the door between the studio room and the kitchen, as this is currently a fairly light panel door with a gap underneath, and an ill‑fitting top edge to the frame (originally it was an open archway, but the door had since been fixed on the inside of the music room to close against the arch).
We suggested that the door panels be filled in with plasterboard, and then a sheet of 10mm MDF fixed on top to add mass and thickness, which would be cheap and easy to do. A wooden threshold strip would need to be fitted to the floor at the bottom of the door, then wooden beading with a compressible neoprene strip glued to one edge could be pinned around the frame on all four sides. This should provide a seal when the door is closed and, again, it would be pretty easy to do. It wouldn't be a complete solution, but it would certainly make a significant improvement over the current situation.
That pretty much concluded what we could achieve in the few hours that we had available, so after a final raid on the Hob Nob stash, we set a course for home.
Michael Coghlan: "A very interesting, informative and biscuit‑filled experience. I've already heard and felt the improvements to my mixdowns; I think the combination of the new Vicoustic foam, a slight movement of my speakers and the Silent Peaks speaker platforms have made a world of difference. I'm finding that what I produce in Cubase sounds a lot closer to what ends up on CD, not only improving my workflow but also saving me some money on CD-Rs!
"The tweaks made to my patching and wiring have given me a more ergonomic workstation and reduced the amount of rewiring required to record a good vocal or a mix from my turntables (which I'm now recording directly into Cubase). The new vocal‑recording environment has been tested, and despite having to remove a Disney duvet cover every time I need to record a vocal, the time spent is more than made up for by needing fewer takes and less processing to produce a hiss-free vocal."The big revelation, though, has been the versatility of my Line 6 KB37 interface, as previously I was only using it as a controller and I had overlooked its other attributes: the high‑quality, built‑in soundcard, easy‑to‑use interface and, more importantly, the cool VU meters that make a lovely change from the digital ones I spend my time studying.
"The discovery of the Freeze function in Cubase has helped me immensely, too, freeing up CPU power to work more quickly and with less latency. I have now finished my hard‑limiting rehab program too; all of the activities above are producing a more powerful, dynamic and polished sound, leaving less need for me to push everything louder through the Waves L2 limiter. It's been a thoroughly enjoyable experience, and SOS has helped me beyond measure. To listen to my improved music, please go to www.soundcloud.com/dj‑d‑mix. You can also catch myself and DJ Evolve playing at Lowdown at the Purple Turtle in Reading every other month. Thanks, Sound on Sound, for all of your help!”