Yohann Abbou | Paris, France
Guitarist, Composer & Engineer
Studio Grade Acoustics
Small rooms are every acoustic engineer’s nightmare and every musician’s reality. It is a fact of life today, that small room sizes and volumes are the norm. How do we get good definition and separation with our bass notes? How do we achieve a definition and separation with our mids and highs. How do we achieve a spectral balance in which everything is represented equally and all sounds heard in their proper context and place in the mix?
Todays Small Room Requirements
First, we must tighten up the low end. To do this, we have to have a certain amount of square footage of coverage of the proper rate and level of absorption for the chosen room size/volume/usage. We all know there are three types of low frequency technologies available to us. They are membrane, diaphragmatic, and Helmholtz. Only diaphragmatic will suit the needs of today’s small rooms. Membrane does not have the horsepower and Helmholtz is too frequency specific. Both require numerous units to achieve performance parameters. Only diaphragmatic, with our internal carbon fill, will produce the rate and level of absorption required in today’s small rooms.
Using our carbon technology, which was shipped from our London facility and throughout Europe, Yohann built 8 of our BDA units using our DIY series of build plans. This provided 32 square foot of absorption below 100 Hz. that had 35 % absorption at 30 Hz., 65% at 40 Hz. and 100 % at 50 Hz. You can view the performance data below in the graph provided. Every 8 sq. ft. of surface area will attenuate 2 dB. With 8 units, we are providing 16 dB of low frequency attenuation, which in most small rooms is a good start. Sometimes you can never have enough.
Managing The Fundamentals
When you have a small room and you can determine this by consulting our room size and volume graphic, you must first and foremost focus on frequencies below 100 Hz. These frequencies have fundamentals below 100 Hz., along with the associated harmonics that extend above 100 Hz. – 1,000 Hz. You must manage the fundamentals, so the harmonics will not be an issue. Most red and yellow zone rooms will need between 120 – 160 sq. ft. of low frequency absorption technology. Most will need more up to 160 sq. ft. of diaphragmatic absorption and not just standard diaphragmatic absorption if it is a room that has multiple sources.
Our carbon technology can take a standard diaphragmatic absorber and improve the performance by 35 %. It is an internal cabinet fill material that has large rates and levels of absorption per cubic inch of material. If you take a tablespoon of carbon, smash it into powder, and spread the powder out, you will have over 200 sq. ft. of absorbing surface area. If you add 55 lbs of this powerful, sound absorbing, material inside of a diaphragmatic absorber that is designed to handle this rate and level of absorption, and build the correct cabinet with the required depths and densities, you have created the world’s most powerful low frequency absorber below 100 Hz.
ACDA Series Absorption Performance Chart
- ACDA-10 Absorption Coefficient in %
- ACDA-12 Absorption Coefficient in %
The red group are rooms that produce so many low, middle, and high frequency energy issues, that large amounts of absorption treatments are required. There is not enough space for diffusion in terms of surface area or distance for wave lengths to fully form. It is the room sizes that are below 2,000 cu. ft. in total volume. The large amounts of treatment surface area, especially in the lower frequencies, will take up so much space that you might not be able to work in it.
The second group (yellow) of room sizes is from 2,000 – 4,000 cu. ft. This group of room sizes and volumes has the necessary space to allow for enough low, middle, and high frequency absorption along with enough space for diffusion. You have the space to place the appropriate low frequency absorption technologies and enough distance for diffusion to work. You will still have issues, especially in the low end but they can be predicted and managed.
The third group (green) is greater than 4,000 cu. ft. It is an ideal grouping of width, height, and length to allow for almost any usage. These rooms have enough distance to allow for appropriate management of all reflection time signatures, unwanted modal pressures, along with enough distances to allow for diffusion to do its job correctly and allow for all diffused wave forms to fully form.
ACDA-12 Activated Carbon
The ACDA-12 is our flagship, activated carbon, broadband, diaphragmatic absorber with low frequency absorption from 30 Hz. – 100 Hz. The face of the unit can be used to support one of our foam absorber thicknesses or one of our mini-diffusors in our MDP line. Units are designed with rigid side and rear walls and a dual wall, front panel construction that increases diaphragmatic action. The inside of each unit contains our activated carbon filters which increase the unit’s Q value through acoustical compliance enhancement. This activated carbon filter process is unique to low frequency absorbers and is patent pending. Solid wood and paint finishes are available. Each unit measures 60″ tall, 30″ wide, and 16″ deep. Each ACDA-12 unit weighs 225 pounds.
All rooms need low frequency energy control, unless you are fortunate enough to have a room that measures at least 30′ in one of it’s dimensions. The ACDA-12 is designed to be a broadband, linear, absorber targeting the 30 Hz. – 100 Hz. range. It is even effective at higher frequencies. With the ACDA-12 unit, you can also control unwanted middle and high frequency reflections through the application of one of our foam thicknesses, mini-diffusors, or a combination of both.
About Yohann Abbou
Yohann Abbou is a guitarist, producer and engineer from France. He is the co-founder of the music label Y-d music which has been founded in 2005. Playing the guitar for over 20 years, Yohann has become an expert in his profession working with various artists from different genres as well as giving guitar masterclasses and teaching guitar lessons.
Yohann has performed live with his band “Electro Quartet” in many venues across Paris, France. Currently he is working on the bands third studio album.