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Studio SOS: Henry Froelich

Your Studio Problems Solved
By Paul White

This is Henry's studio at the beginning of the Studio SOS visit. It's a typical small box-room, and as you can see it was unsullied by acoustic treatment! A plus point, though, was the Yamaha NS10M monitors, which don't put a huge amount of bass out into the room and have a fast transient response, helping to avoid some of the problems at the bass end that plague so many small rooms.This is Henry's studio at the beginning of the Studio SOS visit. It's a typical small box-room, and as you can see it was unsullied by acoustic treatment! A plus point, though, was the Yamaha NS10M monitors, which don't put a huge amount of bass out into the room and have a fast transient response, helping to avoid some of the problems at the bass end that plague so many small rooms.

We get the best from an ageing Mac and tame the worst acoustics problems in a small studio.

Henry Froelich is French but lives in the UK, where he works for Line 6, a well‑known music-equipment company on the guitars, amps and effects side of the industry. Due to his expanding family, Henry has relocated his home studio to the smallest room in his house. An estate agent might describe it as a bedroom, but 'box room' or 'cube' would be more accurate! Henry somehow managed to get all his gear in and wired up, so that he could carry on recording — but he soon discovered that the sound he was hearing from his monitors wasn't very good.

He was also having issues with his computer system, an ageing Mac G5 tower running Apple Logic Pro 8, hooked up to a Line 6 Toneport UX8 interface and an M‑Audio Keystation Pro 88 master keyboard, with a Korg Triton Rack synth tucked away at the back of the desk, beneath a TL Audio Ivory 5060 valve compressor/preamp. Monitoring is via a Samson power amp feeding a pair of Yamaha NS10s, and Henry also has a nice pair of AKG headphones for working quietly and for vocal monitoring. The challenge for this Studio SOS, then, was to see how much of an improvement I could make given the size and shape of the room.

On Arrival

When I arrived, Henry's speakers were aimed down the longest axis of the room, which is what I usually advise — but with only 10cm difference between the wall lengths, I wasn't expecting great things! The size of the room meant that Henry's head would be almost exactly in its centre, and almost halfway between the floor and ceiling. Rooms with a near‑cube shape have the most uneven bass responses, because their widely‑spaced room modes all pile up at the same frequencies. Furthermore, where the room is small, the engineer usually has to sit near the centre, and there's often a severe dip in bass end at that point too, due to a significant amount of phase cancellation taking place.

Theoretically, sitting at the centre of a spherical room would be worse, but in normal domestic spaces, small cube‑shaped rooms have the greatest potential to be acoustic nightmares. Not only do they suffer from the aforementioned problems, but they don't have enough space to add effective acoustic treatment, particularly of the sort needed to solve low‑frequency issues.

Closer Examination

Playing some commercial material in the room, though, I was surprised: the low end wasn't as uneven as I'd expected. Although there was some drop in perceived bass in the centre of the room, it wasn't as severe as I'd feared it might be. Closer examination revealed that, being on one corner of the house, the room has two solid walls facing the outside world, and two internal walls of relatively lightweight plasterboard on wood framing. This worked in our favour, as some low-frequency energy passes through this type of partition, but there's also some absorption as the sound energy attempts to vibrate the plasterboard, losing some of its energy to friction. Two windows and a lightweight door contributed further to the bass leakage and trapping of the room.

Henry had also set up his system slightly off‑centre, so as to accommodate his audio gear and his rack of rather nice guitars, so the two speakers were at different distances from the side walls, which probably helped add a small random element to the modal behaviour of the room! A final factor working in Henry's favour was his Yamaha NS10m monitors. These have a fast transient response and don't kick out a lot of deep bass. I thought that, as long as Henry is prepared to lean back in his chair to clear the slight centre‑of‑room bass null when making critical mix decisions, the low end would prove acceptable.

No Stereo?

The stereo imaging, though, was almost non‑existent, and the hard walls lent a somewhat boxy tonality to the room sound. Although the relatively thin acoustic foam we often use when treating domestic rooms only deals with the mids and highs, the difference between an untreated room and a minimally treated one can still be huge.

I added a relatively small amount of acoustic treatment, comprising just four 2 x 4-feet panels of two-inch Auralex foam, plus some Auralex Mopads to replace the bits of furniture foam Henry was using to isolate his speakers from the desk. Mopads are cut at an angle, and in this case the extra foam wedges that came with them weren't needed, as the pads alone tilted the monitors at just the right angle to point the tweeters at Henry's head when seated. I suggested he try our trick of putting a heavy floor tile under each speaker, on top of the foam, as the increased mass can help tighten the low end.

To put up the acoustic foam without sticking it directly to the walls, I stuck unwanted CDs to the back of the foam panels, so they could be hung on nails or screws. The side mirror-points overlapped with the windows, so we used nails hammered into the window frame to hang these two panels. Part of the window was obscured by foam, but it would be easy to remove the panel when not doing critical mixing. The remaining two panels were fixed horizontally and centred at head height, one on the rear wall and the other on the wall behind the desk. That required three more CDs per panel.

This diagram shows the dimensions and layout of Henry's studio after the Studio SOS 'makeover'.This diagram shows the dimensions and layout of Henry's studio after the Studio SOS 'makeover'.

Replaying our commercial test mixes with the foam in place revealed a much better‑defined stereo image and a generally clearer sound. This room is never going to be brought up to mastering-suite spec, but at least these simple fixes made it usable!

The Big Freeze

Henry's ageing G5 Mac had been running out of CPU power, even on some seemingly simple mixes, and he'd experienced some missing icons and nonsense file names. I suggested rebuilding his system drive's disk permissions, a process that's accessed via the Disk Utilies section of the Applications/Utilities folder. After chuntering and whirring for a few minutes, the Mac declared everything fixed, and displayed a list of minor problems that had been corrected.

The Logic project that was giving Henry problems used an instance of FXpansion's BFD software drum instrument (with its outputs fed to separate Logic mixer channels), a virtual tonewheel organ, one Space Designer reverb, and a handful of low CPU‑overhead gates and compressors. The CPU meter registered an excessive peak shortly after the track started to play, so I recommend the Freeze Tracks option. Many DAWs offer something similar, the idea being that a track using power-hungry plug‑ins can be temporarily rendered as an audio file, with any effects or soft synths printed in place to reduce the load on the computer. If you need to make changes, you unfreeze it, make your adjustments, and re-freeze. Henry's system wasn't showing the track Freeze buttons by default, so we ticked them in the 'Configure Track Headers' dialogue under Logic's View menu.

We froze the organ track, which was going through some pretty intensive amp modelling software to add a bit of grit, and this brought the CPU meter reading down by half! We couldn't freeze the BFD track, though, as its separate outputs fed different mixer channels, but Logic seems to freeze on a per-track basis.

Another CPU‑saving dodge is to start all the audio parts at slightly different times, and also to avoid having audio playing from beat number one. This strategy allows the computer's buffers enough time to fill up and reduces the risk of a CPU spike knocking the system over.

Significant improvements were made to the sound at the monitoring position simply by decoupling the speakers from the desk's shelf with Auralex MoPads, and by placing acoustic foam behind the speakers and at the mirror points.Significant improvements were made to the sound at the monitoring position simply by decoupling the speakers from the desk's shelf with Auralex MoPads, and by placing acoustic foam behind the speakers and at the mirror points.

Henry was already setting up his effect sends correctly so that one send would feed a drum reverb, one a vocal reverb and so on, but he hadn't put these in his default song templates, so he was having to set them up each time he started a new song. In fact, all he'd added to his templates were his drum‑kit setups. Most DAWs allow you to create templates to provide starting points for new projects. It's a good idea to set up one or more of them, containing commonly used instruments, effects sends, effects plug‑ins and screensets — because that way, you can start being creative as soon as you load up a new project. You can also create and lock screensets for different views of the same window. You could, for example, configure three or four screensets showing the Arrange page at different zoom resolutions, or multiple mixer views showing the desired combination of audio tracks, MIDI tracks and Instrument tracks. The smaller your screen area, the more important some of these niceties become!

Buffer Settings

No discussion of CPU overhead would be complete without a mention of buffer sizes. The higher the buffer setting, the less the impact on the CPU, but the higher the latency — so low buffer settings work better for playing virtual instruments and tracking with low‑latency monitoring, but larger buffer sizes free up CPU resources for mixing. Henry was using a 512 sample buffer, which is on the long side for playing software instruments in real time, so I changed this to 256. This caused no playback problems, as long as we left the organ track frozen. By default, Logic has the 24‑bit recording box (in the Audio Preferences pane) unticked, so Henry had been working at 16‑bit resolution. Similarly the 'Independent Record and Playback Fader Levels' option hadn't been selected. This useful feature allows Logic to remember two different channel-fader settings, one for recording and another for playback. I ticked the boxes and returned to the song, to show Henry one more feature...

To the right of Logic's transport bar is a series of buttons, the leftmost of which looks vaguely like a pie with a slice taken out. Clicking this causes it to turn orange and engages low‑latency mode. This temporarily disables any plug‑ins that introduce significant delays, such as linear-phase equalisers, which is useful if you need to do a keyboard overdub without hearing an annoying delay.

Mix Advice

Looking at Henry's mixes, I could see he'd been using a few plug‑in presets, but he hadn't explored Logic's more esoteric plug‑ins. The first thing I did was enable the Analyzer function of the bass part's channel EQ, to show how much energy often resides below 40Hz. Such low frequencies eat up headroom and contribute to mix muddiness without doing anything particularly useful in the audible frequency range. The Analyzer needs to be put in high‑resolution mode to provide any useful information, and if it shows deep bass energy that needs taming, a 24dB/octave low‑cut (high-pass) filter set at 30-40 Hz usually does the trick. We saw some unnecessary sub-bass on the drums, as you might expect — but even vocals can suffer from extreme lows, due to breath or near‑popping events hitting the mic's diaphragm. Cleaning up these problems can really improve the focus of a mix.

Henry hadn't tried Logic's Match EQ, either. This creates an EQ curve that makes the spectrum of one sound match that of another, and it can work very well when you return to a project some weeks down the line and decide that a few bars of guitar or voice need replacing. You simply get the sound as close as you can to the original parts by ear, then let Match EQ create the right EQ curve to match them more closely. It does this by learning a section of both the reference file and your new audio file, deriving an audio spectrum for each, then creating an EQ curve to make the new file's spectrum match that of the reference.

Match EQ has a fader that lets you adjust the amount of the calculated EQ curve applied to the audio. Henry asked me why this had a negative region that inverts the EQ curve to increase rather than reduce the tonal difference. I can't think of any reason to do this when trying to match sounds, but what about when you're trying to 'un-match' them? For example, if you have a vocal that's fighting for space with a distorted guitar, you could use Match EQ to transfer the vocal spectrum EQ onto the guitar part, then use its negative mode to carve a vocal‑shaped hole in the guitar spectrum to allow the vocal to sit more comfortably.

Another plug‑in Henry wasn't sure how to use to its best advantage was Pitch Correct (a near‑clone of Antares' Autotune), particularly when a song changed key or scale modes. It's possible to automate parameters, or even place multiple plug‑ins in series and automate the bypass buttons to bring the different instances into play, but I usually go for the simple approach of placing the various sections of the vocal onto different audio tracks, and routing these via a bus (for adding processing, such as compression). All you then have to do is set the appropriate scale or selection of 'valid' notes in each instance. Henry agreed this would be the simplest approach for him.

After leading Henry into a few other dusty corners of Logic, we had a look at some of the less‑obvious plug‑ins. Henry was genuinely surprised at the sonic possibilities afforded by some of the seemingly simple GarageBand synths — especially the Digital Stepper and the Hybrid Synth — as well as some of the effects and processors that can be found tucked away in the Apple menu, rather than in Logic itself. To my ear, the pitch shifter in the Apple selection actually works a little more smoothly than the one in Logic! The Matrix reverb is also interesting, as it allows you to blend two different algorithmic reverbs.

Finally, for finishing a track (it can't really be described as 'mastering'), I set up Logic's compressor in VCA mode and its limiter, using a low-ratio (1.2:1 in this case) and low threshold, to give around 4dB of gain reduction on the loudest sections. This was followed by Logic's Adaptive Limiter, just to trim another 3dB or so off the loudest peaks, allowing the maximum level to reach ‑0.5dB. I stressed that whenever he was using presets (including the one I'd just created) Henry would need to adjust the threshold levels of any dynamic processors in order to get the desired amount of gain reduction, as their action always depends on the level and dynamics of the input signal, no matter how appropriate the preset's other settings.

Henry tested out the new vocal recording setup, which was much improved by the use of an SE Reflexion Filter in front of the mic, and acoustic foam on the wall behind.Henry tested out the new vocal recording setup, which was much improved by the use of an SE Reflexion Filter in front of the mic, and acoustic foam on the wall behind.
 

Vocal Recording

When it came to vocal recording, as Henry had simply set up his Audio-Technica AT3033 mic in the studio, so reflections from the hard walls had inevitably coloured the sound to a noticeable extent. This becomes more obvious (and less welcome) when the vocal is compressed to even up the levels, and while attempts to bury it in reverb might seem appealing, they never work! Although it would be cramped, it would be possible to record vocals in the now‑treated studio by having the singer stand with their back to the foam panel on the rear wall, and fitting a screen behind the mic to keep leakage out of the rear and sides of the mic.

Once again, Sonic Distribution kindly donated an SE Reflexion Filter, and I set this up on Henry's mic stand, so that his mic was level with the mouth of the screen, as putting it too far inside can colour the sound. I suggested, though, that it might be better to set up the mic stand and Reflexion Filter on the landing outside, where there was more space, and to use duvets or other soft blankets to form absorbers behind the singer. These could be draped over a boom mic stand or even hung on the back of a door. This seemed a better solution, as swinging the proverbial cat in Henry's studio would have resulted in an all-too-familiar 'Miaow‑Thud, Miaow‑Thud' sound!

We explored yet more of the less obvious plug‑ins, and covered some useful EQ settings (such as gentle boosting above 6kHz to add 'air' to vocals), before finishing our final cup of tea for the day and setting a course for home.  

Reader Reaction

Henry: "Thanks again for taking the time to come by and do the Studio SOS, and thanks also to Auralex and SE for donating the acoustics products. I tried putting some drum parts together after you left, and with the new room acoustics the difference in clarity, stereo spread and placement is amazing. In fact, I've actually had to go through all my BFD templates to tone down many of the effects that I'd added!”

Published May 2011