Posts Tagged Model D
Today on, “Similar, yet different…” we are going to analyze two more of our acoustic diffusers and compare/contrast their designs and functionality… and this one is a doozy; The Model D vs. The Aeolian®. These two diffusers have some very interesting similarities and some surprising differences – so lets get started!
We have discussed the Aeolian® construction before, so we will start here with a quick recap as a reference point. The Aeolian® started life as a blocky-looking diffuser – just like the Model C, but the implementation is different. While the Model C retains its “blocky” appearance, the Aeolian® has run through a mathematical process called “bicubic interpolation.” This smooths the transition from one block to the next, creating the wavy appearance of the Aeolian® diffuser.
So, keep that in mind: The diffuser was tuned with different height blocks and then the transitions were smoothed.
The Art Diffusor® Model D has multiple layers of math below its curved surface. While the Aeolian® started life as “Blocks” of different heights… the Model D started life as “Rings” of different sizes and heights. The calculation for the heights is identical to the mathematics used in tuning the Aeolian®, but why different sized rings?
There is an older diffuser design known as a Maximum Length Sequence (MLS) diffuser. These were tuned to different frequencies using a specific depth, and different spacings of “lands and valleys.”
The Model D started with the concept of twisting the MLS spacings into rings, and changing the size of the rings. Then to break the “MLS mold” of having the same depth, this MLS ring structure is raised to different heights using Quadratic Residue calculations… effectively combining the rings of MLS spacings with different QRD heights. While this could have been where this stopped, we wanted to interject more randomness into the equation.
Wherever the rings of different heights intersected, we decided to change the heights by values relative to the difference between the two rings. This height variation is what is responsible for the “random” waviness. This was accomplished with different Boolean Functions, to either add or subtract height where the rings intersected.
This method of using Boolean Functions inserts a known-height randomization into a hybrid MLS/Quadratic system. (That’s a mouthful.) The final step, after refining the ring size, height, position and intersection parameters… was to smooth the whole geometry with “Bicubic Interpolation.” That’s right. This final step smooths all the transitions from the heights, just like the blocks of the Aeolian®.
So onto the Simple Similarities!
Both diffusers use a quadratic residue calculations to get the main heights of the diffusive elements. Both diffusers are finished off with a helping of “Bicubic Interpolation” to smooth it all out. This gives them both a very organic look… The Aeolian® looks a bit like rolling waves, and the Model D resembles droplets of rain in a puddle…
They do perform quite a bit differently though.
The Aeolian® has great lower mid-band performance… while the Model D is a beast in the upper mid-bands starting about 2.5K. The difference is in the severity of the geometry. The Aeolian® is a gently rolling surface which redirects the waveforms uniformly through a wide range of frequencies. The Model D has a very irregular surface. With the different ring sizes, heights, locations and boolean functions… it’s meant to target and shred mid to high frequencies. Both diffusers are asymmetric – and affect different frequencies in different ways.
The Aeolian® is also deeper than the Model D – and this depth is a single resonant cavity… allowing it to be a great bass absorber as well. The Model D is useful in environments where you have bass control in place, but really need to diffuse the upper mid range and bring those frequencies to life… or maybe shred some flutter echos or comb filtering. There are scenarios where both are used in the same environment – but for different reasons.
While both the ArtDiffusor® Model D and the Aeolian® both look like liquids frozen in time, they have some other similarities in the math behind them… Yet they are still as different as rolling waves versus droplets of rain in a puddle.
Acoustics First® Art Diffusor® Model D spotted in music video for Usher’s “Rivals” featuring Future…
Watch the video on YouTube here… Usher – “Rivals” Featuring Future.
Nick Lane, an independent audio engineer whose credits include Rascal Flatts and Reba McEntire, contacted Acoustics First® seeking help with his project studio. This process would convert the bonus room in his house (a second floor space above his garage) into a Project Studio.
After receiving some measurements and photos, we went to work designing a layout for the space.
Placement of panels and ceiling clouds were optimized to reduce early reflections and trap bass, and a combination of Model D’s and C’S were used to widen the “sweet spot” of his room.
“Sounds really good!….. High end is sooo much less harsh…… walking around the room, the low-end doesn’t disappear in places anymore” – Nick Lane
As many of you know, Acoustics First® invests a great deal of energy in the development of the science of acoustics. Here are three ways that we are making advances that help people learn and actually Visualize acoustics!
Those interested in sound diffusers have certainly noticed that Acoustics First® has produced a Diffuser Data book, containing all kinds of test data about how our diffusers contribute to the sound in your space. This information is a great advancement and we have worked closely with the ASTM committee developing this test method. Some people wonder exactly how the test produces the data that we report, and we have developed a simulation to show exactly how the sound energy is sampled during this test.
Acoustics First – Diffuser Data Test Demo from Acoustics First®.
We have also made leaps and bounds in using simulations to show the different ways that diffusion develops in a space. Depending on the type and placement of the diffusers you install, the diffuse field will develop at different speeds, at different frequencies. We can now show a couple of simulations of the development of a diffuse field to help you visualize how sound moves in room without treatment and with two different sets of diffuser treatments.
Acoustics First – Room Simulations from Acoustics First®.
Bonus video! Imagine being able to see the Untreated room and the Model D room from a different angle – To be able to move around the outside of the room and see how the sound field develops from a different perspective. Imagine no more! Here it is!
Acoustics First – Sound Field Development Simulation – 3D Panning from Acoustics First®.
If you prefer to use YouTube – you will find the videos uploaded at our YouTube channel here.
We hope these helped you to “look” at acoustics in a whole new way, and stay tuned – more advancements are coming soon!
With current trends leaning toward improving the quality of life for all creatures living on our great planet, we at Acoustics First® feel that we can contribute to this in our own small way.
So we proudly introduce, the ArtDiffusor® – Micro Model D!
Birds are very musical creatures, in the past, while Beaker was listening to the Bee Gees, he was bombarded with harsh specular reflections and flutter echos, it was a tragedy – but no longer.
Harsh acoustic environments are not for the birds… The ArtDiffusor®- Micro Model D… is.