We don’t need to be running a recording studio to care about speaker placement. Broadcast facilities are full of audio monitoring rooms for a range of uses. The principles discussed in this talk by award-winning studio designer Carl Tatz can be put in to practice wherever you want to sit in a room and listen to decent, flat audio.
Joining Producer Mike Rodiguez who moderates this webinar for the Audio Engineering Society (AES), Carl focuses this discussion on getting the right sound in audio control rooms. This is done through the ‘Null Positioning Ensemble’ (NPE) which considers the mixing console, listener and the speakers ‘as one’ that can be moved around the room. The ensemble puts the two speakers at about 1.71m apart behind the console firing across the console. Their audio intersects 45cm in front of the console where the listener can sit forming an equilateral triangle. By sitting between the console and where the speakers cross, Carl says you hear the source rather than the speakers thus giving the best audio reproduction.
This effect works if the tweeters are at the same higher as the listener’s ears, says Carl, so should be adjusted to suit the listener. High frequencies are more directional than lower frequencies so for accurate listening, it’s important the speakers aren’t pointing too far off-axis. Exactly where to place your ensemble can seem daunting, but Carl has a calculator on his website which gives a great start allowing you to model your room as a rectangle and find out where the null points are going to be. The nulls are where sound cancels out due to reflections so moving your ensemble to avoid these nulls is the key to a great sound. Carl details how this is done and how, then, to optimise for the ‘real world’ room rather than the mathematical model.
Carl talks about the importance of sound treatment to remove reflections and stop the room from being too lively, with some specific suggestions. In general, the aim is to remove first reflections, have the back stony dead, the ceiling dead and bass traps in the corners. This should allow you to clap your hands without hearing reflection. But you can’t fix every problem with such treatment, Carl says, bringing up a frequency chart of a typical monitor setup which shows a 10dB dip around 125Hz. This is found in all monitoring setups and appears to develop from sound from the speakers bouncing off the floor under the console. He says that this needs to be filled in with subwoofers rather than being fixed with EQ or acoustic treatments.
The fundamentals of building a studio are the same whether for TV or Radio. You want to keep sound out…and in. This has forever been a challenge which doesn’t stop when the room’s built. Before it’s pressed into use, you have to lay it out correctly, considering the equipment, acoustic treatments and keep it cool.
Fortunately, experts from the BBC and Global are here to talk us through it at this Masterclass from Radio TechCon. Dave Walters from the BBC kicks off explaining how the aim of isolating your studio from physical vibration both through the structure and through gaps in the walls, floor or ceiling. Once isolated from the outside, the task is to manage the sound in the room and that calls for acoustic treatment. Dave goes through the options for lining the ceiling and walls showing that there’s acoustic treatment at all budgets. Dave finishes by highlighting that the aim is to dissipate sound and not let it bounce around. This means reflective surfaces such as glass windows need to be angled so they don’t directly point at any other hard surface.
With a deadened acoustic and a quiet atmosphere, your studio is ready to be occupied. Stephen Clarke from Global talks through laying out the studio taking into account what people do and don’t want to see. The presenter, for instance, will want to see through to the control room for visual cues during the programme, but it’s best to keep guests pointed away without distraction. This can also extend to the placement of TVs, computers and other equipment. Equipment, of course, is a concern in itself. As it generates heat and, often noise, it’s best to minimise in-studio equipment which can be done with a KVM system. Stephen talks us through a photo of the Today studio to see these principles in action.
To finish up, Global’s Simon Price talks about making holes in the studio that Dave managed to isolate. The inconvenient truth is that people need oxygen, generate heat and generate odour. Any one of those three is a good reason to put air con into the studio so Simon explains the use of baffles in ducting used to introduce the air. This absorbs sound from the air’s movement and also any external sounds that happen to come in. Simon concludes by explaining safe electrical distribution for studios keeping wiring to a minimum and reducing fire risk.
Before leaving, the team have just enough time to answer a question about studios with large amounts of glass and how to choose how ‘dead’ you want the reverb in the studio to be asking ‘can you go too far’ in minimising sound.
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