The Studio SOS Book: Practical Monitoring Solutions
Paul White, Hugh Robjohns, and Dave Lockwood

   By Guest Contributor   Categories: Audio EquipmentProducingRecording

The most important areas to treat are the so-called mirror points – those areas of reflective surface that bounce the sound from the monitors directly back to your listening position. You can find these by getting someone to hold a real mirror flat against the wall when you are seated in your usual monitoring position. At any point where you can see a reflection of either monitor speaker in the mirror, you need to place an absorber. The main mirror points in a typical rectangular room will be on either side of you, slightly forward of where you sit, and also on the wall behind the speakers. In a typical bedroom or garage studio, you may find that one square metre of suitably positioned absorber per wall is enough. In general use the thickest acoustic absorbers you can accommodate, and ideally leave air gaps behind the foam if at all possible as this makes the traps more efficient at lower frequencies. You may remember that we suggested that if mounting foam on board, then select a board with generous perforations where possible because with solid MDF or plywood boards any benefits of leaving an air gap behind the trap are lost.

There will also be an area on the ceiling, roughly halfway between your monitors and your ears, where an absorber could be helpful. If you don’t want to stick foam to the ceiling, build a lightweight wooden frame to hold a sheet of foam or mineral wool and suspend it on wires or chains from cup hooks or plasterboard fittings screwed into the ceiling, which is far less intrusive than using glue. Hang your absorber roughly 100 to 200mm below the ceiling to increase its low-frequency efficiency. If there are lights above the ceiling panel, consider fitting LED lamps to avoid heat build-up.

Figure 1: Any non-absorbent surface on which you can place a mirror and see your speakers reflected is a potential source of reflected sound.

Commercial acoustic panels are available in both square (typically 600x600mm) and rectangular (600x1200mm) forms, and we’re often asked whether it’s best to hang rectangular acoustic panels vertically or horizontally. The answer is that it depends on the room size and layout as well as the aesthetics – there is no right or wrong way! In larger rooms, you can also double up on the panel area.

We’ve come across many situations where the ideal sidewall absorber placement has coincided with entrance doors, cupboard doors or windows. One solution is to make up a removable lightweight foam absorber that hangs from a hook on the back of the door or cupboard. Self-adhesive plastic hooks are usually fine for this and you can stick an old CD onto the back of the foam panel to hang over the hook. Acoustic foam can be fixed using the recommended spray contact adhesive, but be warned that once fixed to a hard surface it puts up a real fight if you try to remove it at a later date, and you’ll probably end up with a layer of foam still stuck to the wall! Often it is safer to fix the foam to an MDF or plywood panel, or easier still an old CD, that you then hang on a picture hook. Spray adhesive designed for acoustic foam is the best option, though regular contact adhesive can be used for fixing small items, such as CDs, to the back of a panel. Better grades of carpet adhesive also work but we’ve found that some brands don’t grip strongly enough, and some can dissolve the foam – so always try a small area first!

Figure 2: A room with all the primary reflection points treated.

Figure 3: Gluing an unwanted CD to the back of a foam tile allows you to hang it on a picture hook so that it can be placed temporarily and removed without damaging the wall.

If a mirror point coincides with a window, then heavy curtains are the simplest answer, although we’ve also had good results making a removable foam absorber panel which could be hung up or balanced on the window ledge only when mixing. Vertical blinds set at a 45-degree angle can also be useful in breaking up reflections. Movable panels are useful in small studios anyway as during tracking you can use them to improve the acoustics around an instrument or amplifier when recording with microphones.

In some rooms perfect symmetry simply isn’t possible, as we’ve sometimes found in bedroom studios we’ve visited. All you can do in such cases is to try to make the listening area as symmetrical as possible from a mid- and high-frequency point of view, and this can often be achieved by hanging a temporary foam panel to one side or other of the monitoring position when mixing. For example, if your desk is close to a wall on your left, then prop up a temporary foam panel on your right to make something resembling another similarly treated wall. Another easy temporary fix is to hang a foam panel wherever necessary from a boom mic stand using a couple of those woodworking clamps that look like giant clothes pins.

TIP: If you accidentally get some spray adhesive on the surface of acoustic foam or other furnishings, you can often remove it before it dries by dabbing at it with the sticky side of Gaffa or duct tape.

Figure 4: If you can’t permanently mount any sound absorption in your studio room, you can always improvise some temporary absorbers when you are actually working.

MONITORING DO’S AND DONT’S

DO arrange your monitoring setup as symmetrically as possible.

DO put your speakers on rigid stands or, if mounted on a desk, isolating pads.

DO place acoustic absorbers at the mirror points.

DO move your monitor position to achieve the most even bass. DO scatter or absorb reflections from the wall behind you.

DO continually compare your mixes with commercial mixes in a similar style.

DON’T allow objects to get between you and the monitor speakers. DON’T site monitors too close to room corners or back walls.

DON’T sit in the exact centre of a square or rectangular room.

DON’T sit close to walls or corners when monitoring.

DON’T use too much broadband absorption or the sound of the room may suffer.

DON’T rely too much on your monitors in a small room – double-check the mix on headphones and on as many third-party sound systems as possible.

 

Excerpt from The Studio SOS Book: Solutions and Techniques for the Project Recording Studio by Paul White, Hugh Robjohns, and Dave Lockwood.

About the Authors

Paul White is Editor-In-Chief of Sound On Sound. Trained in electronics, he has been recording music since the 1970s. He also performs and mixes live gigs, and is the author of a number of music recording textbooks.

Hugh Robjohns is the Technical Editor at Sound On Sound. Trained at the BBC, he has lectured at the Corporation’s technical training centre and continues to deliver specialist training to broadcast organisations around the world.

Dave Lockwood is the Editorial Director of Sound On Sound. Formerly a professional musician and studio engineer, he is also a best-selling artist at the guitar-tuition website JamTrackCentral.com.

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