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Control Room Design

By December 21, 2012No Comments

Control Room Goals

The primary goal of control room design is to achieve a flat or smooth frequency response that would translate into a similar response time in domestic and consumer rooms. This room response was also to have a decay rate that was equally representative of end user listening rooms. Our acoustic goals for our control room on the professional side was a compatibility between control rooms so a mix in one control room would translate into another control room. Secondly, our control rooms must be designed to provide a comfortable working environment for the engineers who must spend hours working in the control room.

Standardization

In order to make sure that mixes that are made in one control room will translate into another control room we need a standard set of conditions present in one control room translates into another control room. The European Broadcasting Union tried this standardization many years ago but could not get anyone to agree. Control rooms are all different and dissimilar.

Monitor Location

The first and most important factor in any control room standardization process is the location of the monitors or loudspeakers. The location of the monitors is directly responsible for the frequency response in the control room. The position of the monitors is directly responsible for the cumulative response and blending of the direct and reflected sound which is critical to any uniformity or standardization of sound. Flush mounting of the monitor speakers in the front wall will go along way to achieving some sound standardization and cross studio translation. A control rooms goal is to add nothing to the mix sound.

Near Field Monitoring

Near field monitoring is a best effort to minimize room response issues. With near field monitoring, engineers can hear the sound of the monitors with minimum room sound entering in to the equation. With near field monitoring we are sitting within the critical distance. The critical distance is the area where the direct sound or straight line sound from the monitors predominates. With monitors positioned within the critical distance, the reflections from room boundary surfaces are minimized. Lets push the critical distance to be “outside” the boundaries of our control room. lets design rooms that have all reflected energy under control.

Near Field Pros and Cons

Near field listening has its benefits and disadvantages. If everyone near field listened, we would have a large number of engineers who at least knew of the sound of a group of monitors. This would be a benefit for all concerned. Work performed on near field monitors could be judged and compared with other control rooms. However, near field monitors lack good transient accuracy and can not reproduce the lower critical bands of energy that provide the foundation of low frequency energy in our mixes.

Dynamic Range Limitations

Dynamic range of near field monitors is also limited. Without the ability to have dynamic range response in our monitors, we can not assess the critical low level detail. This low level detail can only be realized if our loudspeaker has the necessary dynamic range to permit the distance between low and high energy passages to be heard. What we need to do is to extend the benefits of near field listening, namely staying within the critical distance parameters to the rest of the room.

Low Energy Management

We also need our rooms to provide the proper rates and levels of low frequency control and management, so that our critical distance is available throughout the room and low frequency pressure build ups will be evenly distributed within the room. We need low frequency absorption that can handle the lowest frequency issues our room dimensions dictate and also provide the proper amount of absorption to provide the necessary attack and decay so necessary with lower frequencies.

Golden Ratios

Proper room dimensions are critical if we are to have a running start to manage low frequency energy. It is always better to choose the correct room dimensions to minimize the impact of room dimensional resonances. Certain room heights, widths, and lengths are more favorable to producing less room resonances. We need to find those “golden ratios” and utilize them in our room size choice. We may even have to make the room smaller to allow for reduced modal resonances.

Reflection Control

Near field monitoring minimizes the impact of room boundary reflections. If we are to extend this concept to the whole room, we must use current absorption and diffusion technologies to bring the rate and level of these reflections down below the direct sound from our control room monitors. We must address the rear wall reflections that produce a time delayed signal of its own at the listening position. A balance of current absorption and diffusion technologies can accomplish this for us.

Ceiling And Side Walls

Ceiling and side wall reflections must be addressed in a similar fashion as our rear wall. We must use a balance of absorption and diffusion technologies to reduce the time signature on these surface reflections, so that it does not interfere with the direct sound from our monitors. Near Field monitoring is a direct response from engineers to minimize these surface reflections by sitting closely to the speakers. We need to extend this concept by treating the whole room so it does not produce the reflections that engineers are running away from by sitting near field.

Standardization Components

If we place our monitors in a surface mount position in the front wall and treat all room boundary surfaces with the proper amount of diffusion and absorption technologies, we can go along way to achieving some type of standardization in the monitor or control rooms of our studios. Front wall flush mounting will standardize the frequency response in our rooms and the treatment of all room boundary surfaces will minimize the impact of these time delayed energy on our mixes. Proper room dimensions and boundary surface reflection control are a must if we are to begin to achieve the direct versus reflected energy ratio we must have for any control room standardization to occur.

MikeSorensen

Author MikeSorensen

I am a structural engineer as well as a master furniture maker. I design cabinets for low frequency, activated carbon absorbers. Connect with me on Google+

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