Rooms Panels Bass Traps Diffusers GOBOs Clouds Recoils
Technology of London Room Kits

The plain fact is that most studios, whether in the home or in a commercial building, tend to have a rectangular shape as this is the most cost effective method of building a room. Unfortunately, this makes the room ineffective for creating music. Parallel walls introduce chatter echo and standing waves while room modes cause resonant frequencies and harmonics which detract from the performance.

We have taken the current thinking on studio acoustics and applied it to small rooms typical of personal studios. Then we packaged a selection of Broadway acoustic panels in an LEDE type arrangement that addresses each wall surface to create a balanced recording and mixing room. Here are some typical room acoustic issues and how the London kits solve the problem:


Side Walls

Green = Direct sound from monitors
Pink = Primary reflections from side walls


Before Acoustic Treatment
Side-to-side flutter echo and primary reflections from the monitors reduce imaging and cause listening fatigue as the ear tries to selectively listen to the source while competing with powerful primary wall echo.

After Treatment
Broadway 12" x 48" Control Columns reduce the amplitude of primary reflections from the side walls and help balance the room for proper left-right imaging. When placed on the front (source) wall, they also serve to reduce flutter echo and standing waves between the front add back walls. These are mounted using Broadway Surface impalers and are positioned strategically on nearby wall surfaces.

Front Wall


Green = Direct sound from monitor
Pink = Primary reflection
Orange = Secondary reflection
Blue = Tertiary reflection


Before Acoustic Treatment
Front-to-back room flutter echo and standing waves are created by the monitors firing at the rear wall and creating an endless echo as they reflect back to the front wall. All monitors, and especially those with rear firing ports stream bass directly to the front wall creating a comb filtered effect and uneven bass response.

After Treatment
This is resolved using 24" x 48" Broadband panels and 12" x 48" Control Columns. The Broadband panels along with the Control Columns, act to absorb front to back flutter echo. Corner mounting the Broadband panels using Broadway Corner impalers traps bass and helps even out low frequency response.


Rear Wall


Green = Direct sound from monitors
Pink = Primary reflections from rear wall




Before Acoustic Treatment
Rear-wall reflections require a balanced solution. If left untreated the primary reflections from the rear wall can interfere with the direct sound. If completely deadened, the room becomes dark, listless and the resulting mixes will tend to be overly bright.

After Treatment
The solution is to introduce the LEDE concept or live-end, dead-end with one end brighter or more alive and the other end quieter with more absorbing materials. Broadway 12" x 12" Scatter Blocks on the rear wall allow some of the random energy to reflect back into the space while controlling the remainder. We call this 'Soft-Diffusion' and it creates a more natural listening environment while also working with the front wall Broadway panels to reduce standing waves and room chatter. These are mounted using Broadway Surface impalers.


Bass Trapping (Nulls and Peaks)

Bass control is essential in any room. All rooms have resonate frequencies which form modes. The modes get distributed around the room based on their wave-length and the rooms dimensions. Some locations in the room will be mode "cold spots" or "nulls" where the resonate frequencies combine in a destructive way (see example 1 below). Null modes produce a dip in the rooms response. If your listening position is in a null you will experience less bass than what is represented in the original signal.

Other locations will be mode "hot spots" or "peaks" where sound waves combine in a reinforcing way (see example 2). Peak modes produce a bump in the rooms bass response. If your listening position is in a peak, the bass may seem over-powering at certain frequencies. The nulls and peaks are the extremes, however, locations in between will experience some degree of bass coloring as the direct sound from the source (subwoofer) and reflected sounds combine to produce various degrees of comb-filtering (see example 3).

The goal for bass traps is to absorb low frequencies before they can setup standing waves between surfaces. By absorbing the bass energy, the rooms bass response evens out and the sound from the monitors is natural and truer.




The direct sound (A) from the subwoofer arrives at the listening position followed by the reflected sound (B) a few millisecond later. If the two arrive '180° out-of-phase' the sound will combine in a destructive way and cancel each other out. The resulting waveform has little or no sound energy left.


When bass traps are introduced into the room some of the excess bass energy is absorbed and the amplitude of the reflected sound is reduced. The result is less destructive cancellation.

Example 1:
100% Cancellation (Null)








Like the first example, the direct sound (A) from the subwoofer arrives at the listening position followed by the reflected sound (B). This time, the two are 'in-phase' and they combine in a reinforcing way. The resulting waveform has nearly double the amplitude.


Bass traps absorb excess bass energy and reduce the amplitude of the reflection. The result is less destructive reinforcement.



Example 2:
100% Reinforcement (Peak)






In cases where the phase shift between the direct (A) and the reflected (B) sounds is less than 180°, the resulting waveform is affected by comb-filtering. The rooms bass response is "coloring" the sound making it hard to mix with predictable results.


Bass traps absorb the excess bass and lower the amplitude of the reflected sound. With less energy behind the reflection, the resulting waveform is shaped more like the original signal. Because of the bass traps, the room has less of an effect on low frequencies and you hear a true mix.



Example 3:
Partial Phase Cancellation (Coloring)


 



Primacoustic is a division of Radial Engineering Ltd. © 2008 Tel: 604.942.1001 | Fax: 604.942.1010