AudioXPress turned to Acoustics First® for their “Focus on Acoustics” Edition (August 2020), to help shed light on what test data is – and what it isn’t. Many people rely on lab results when trying to find products that meet design criteria… but there are limitations to this data. The “Elephant in the Lab” is that there is no such thing as absolute, repeatable, accuracy in lab tests… and this article brings to light why that is, and why it will likely always be the case.
It also addresses the impact this has on calculation accuracy, simulations, and what is being done to address this issue.
We often get asked about the functionality of the different diffusers, and one of the frequently asked questions is about the differences between the ArtDiffusor® Model C and ArtDiffusor® Model F. We will cover some of similarities and differences in the design, functionality and use of these two devices.
The Model C and Model F use identical math to come up with their basic structure, they even have angled faces – the main difference between the two is that the Model F elements are ½ of the Model C’s height, length and width – and then it is duplicated 4 times in the same footprint… The Model C is nominally 2’ x 2’ x 4” deep. The Model F is four quadrants that are nominally 1’ x 1’ x 2” deep – like little scaled down Model C’s… This makes them visually similar and aesthetically compatible. This low profile design makes the Model F more desirable for ceiling installs in spaces with very limited headroom – like basement studios that have low ceilings.
Due to the different size of the elements on the two devices, they have very different frequencies at which they are most effective. The Model C is a mid-frequency diffuser by design… having larger elements and deeper wells than the Model F. The Model F is primarily a high-frequency diffuser, due to the small elements and lower profile. Both diffusers are tuned to different frequencies as their “primary range,” and while they do affect lower and higher frequencies than they are designed for – it is to a lesser degree, or the product of absorption.
What does this mean?
The Model C has a primary design range of 1KHz to 4KHz. This is where it is primarily designed to work. It can and does diffuse below 1KHz and over 4KHz – just to a lesser degree than its primary design range.
The Model F has a primary design range of 2KHz to 8KHz, and again, it does diffuse outside of that range, but to a lesser degree.
The angled caps of both the Model C and Model F help to extend their high frequency range by reflecting sound in different directions at higher frequencies – causing the sound to scatter spatially. The different heights of the elements cause sound reflections to be offset “temporally,” or in time. The sound that hits the higher elements is reflected sooner than the sound that hits the lower elements – travelling further before it is reflected. This time offset, changes the “Phase Coherency” of the reflection; the larger the difference in the heights, the greater the offset in time.
The size of the elements matters as well. The shorter wavelengths of high frequencies can diffract and scatter off of the smaller elements of the Model F more readily than low frequencies, which see the Model F as a slightly angled & mostly flat surface. However, the lower frequencies are more affected by the larger and deeper elements of the Model C.
How do these differences help define their use?
The Model C is a great all around diffuser – it covers a wide range of frequencies, throws a very predictable 2D diffusion pattern, and it is tuned to a very musical range.
The Model F is a great high-frequency diffuser. It targets a few very specific, yet important issues. High frequencies are responsible for some nasty problems in rooms. Flutter echoes, ringing, comb filtering, and other artifacts are particularly noticeable in higher frequencies. If your room is otherwise performing well acoustically, the Model F can help tackle that last hurdle to make a good room into a great room.
Adding Nouveau™ wood diffusers to a home theater is not as daunting a task as it may seem, and can be done with a little planning and a few tools. This install used an ingenious mounting method to ease the final install. Instead of mounting the z-track to the wall directly, it was mounted to sheets of plywood which were hung with Gorilla/Hercules hooks.
The first task was to pick a stain. You can use the back of a plank to get an idea of how the poplar will respond to the different options. Poplar has a very interesting and varied structure that will take stain differently than some other woods. Darker stains may be more consistent, but don’t reveal the character and variation in the wood. This install chose a Smoke Gray which grayed out soft areas and browned the harder heart wood. A semi-gloss clear coat was used to finish.
While the stain dried, the mounting plywood was cut down to hide behind the planks. Four hanging straps with eye-loops were then added to the top edge of each of the plywood sections, and spaced to avoid studs.
The Z-track that would normally be installed on the wall was installed on the opposite side of the plywood. This will make it easy to hang the Nouveaus onto the sheet after it’s on the wall.
After the Nouveau™ planks are finished with the staining, and left to cure for a few days, they are ready to have the mating Z-bars attached to the back. They are installed with the same spacing as the Z-tracks on the plywood sheets. This will make it easy to align them after the plywood is hung on the wall.
The Gorilla/Hercules Anchor hooks are rated to around 50-60 lbs each. The Nouveau™ planks are roughly 25lbs each (at 48 inches) and each section has 4 hooks supporting 4 planks plus the weight of the 3/8″ plywood. The hooks are installed so that the plywood will hang level – with the weight distributed evenly across all four hooks.
Finally, the Nouveau™ planks are installed into the Z-Tracks on the plywood, and moved into position. Because the z-bars were installed square and level, there is no shifting, and they hang true. The undersized plywood sections disappear behind the planks leaving the impression that the planks are floating slightly off the wall.
While this mounting method may not be ideal for every scenario, this was an effective way to install 8 Nouveau™ planks with only 8 small hook holes in the wall. These can now be installed in apartments or temporary environments with minimal damage to the existing walls – and once you are done, they’re easy to take down and reinstall somewhere else. You just need a level!
It may seem a lifetime ago, but we are celebrating the 3rd Anniversary of the release of the patented Aeolian® Sound diffuser. During development, our team ran numerous models and simulations, revising the design, and optimizing the performance to create the iteration we have today.
The development workflow of the design included computer optimized geometry, performance simulation, rapid prototyping, and full acoustic performance and validation testing. This was one of the first uses of this completed workflow, and while we are always refining our development processes, this was a huge leap forward.
We now look back at the release of the Aeolian® as a milestone in our history, where we developed something more than a product… we developed a better way to design a product.
Let’s say you need some Sonora® Black scrim ceiling tiles for a home theater project, and you order a few extra – “just in case.” Now that the install is done (and you have a few left) you can do something with them… like making a cool absorber panel with lights!
Everyone will have a different vision, but the basic supplies are…
- Acoustic Absorber Material (ex. Sonora® Black Scrim Ceiling Tiles)
- Wood for frame
- Acoustically transparent material/fabric (This one uses a polyester fabric map)
- Material to enclose the back (fabric scrim)
- Wood to mount lighting (This is a 1″x 4″ with espresso stain)
- Lights (here are custom, black-pipe light fixtures, but use other lights if desired)
- Wiring (Wirenuts, electrical tape, lamp cord, etc.)
- Assorted screws, staples, hanging hardware, PPE and tools.
Note: This is not a detailed DIY, as everyone will have a different set of materials and project goals, but these will show the basic steps to create a panel like the one above…. Here we go!
Cut the wood and make a frame that will hold the acoustic material, and the fabric to enclose it. Make the frame big enough to hold the material, and still be covered by the fabric. Make the frame as rigid as possible. Predrill your holes and make it square. Make it tight enough to hold the acoustic material with friction, but without crushing it.
This design is an old map that was printed on a lightweight, polyester fabric banner material. This one is roughly 4′ x 6′ with extra material around the edge to wrap it around the back of the frame. It’s best to have your starting fabric oversize – the graphics sized to the frame, with a boarder wide enough to wrap to the back for fastening. (In this case we will simply staple it to the back of the frame.)
Lay out the material and attach it to the frame. Be careful when putting the frame on the material. Take care in lining up the graphic to the frame, and keep an eye out for wrinkles and folds.
Fastening doesn’t need to be perfect on the back, but you do want it to be secure. Trim up the excess material if needed, and then flip it around and see what it looks like.
You could just fill it with the material and hang it like this if you didn’t want the lights, but this project is going the extra mile! We will attach a board to the top of the frame and attach the lights to that. This board will support the lights as well as the the frame. The hanging straps and rings will be attached to this as well, so don’t select a board that is too thin or flimsy.
How you mount the lights to the board and run the wires will be different if you are using different fixtures. This was made with 5 custom, black-pipe fixtures, that are basically just a flange, two 90° elbows, some pipe, and a lamp fixture mounted in a 1 1/4″ pipe reducer/coupler. Wire was stranded lamp wire (black and white), and it was left long to assist routing the wiring inside the panel.
The flange on these lights had 3 screw holes. Some washers and wood screws were used to attach them to the frame. The remaining fixtures were then measured and mounted – paying close attention to keeping consistent spacing and orientation of the lamps.
Note: This will vary depending on the type and number of lamps you use.
Now that we have all the fixtures mounted, let’s finish the wiring and put in the material!
(WARNING: If you are not comfortable with wiring – this is the point where you call in a friend, electrician, Wikipedia, or whatever other resource you use to make sure you don’t electrocute yourself, burn down the house, etc. Acoustics First assumes no responsibility for your DIY projects – but we wish you good luck!)
This wiring was all attached to a lamp cord that had a pre-molded plug, and readily recognizable hot (black) and neutral (white) wires. This entire fixture is being controlled by a smart outlet (“Alexa… Turn on the Awesome World Map.”), but could just as easily be hard wired to a junction box, or wired with an inline switch.
This is a good opportunity to test the lights and wiring, before installing the acoustic material and covering the back.
Now we can insert the acoustic material. Sonora® Black Scrim Ceiling tiles are easily trimmed to fit with a sharp knife. They are fiberglass! So… wear gloves minimize exposure to the fibers.
Covering the back of the panel will keep the Sonora® tiles in place, and keep any stray fibers from escaping. This will also make the panel easier to move in the future – without worrying about the tiles falling out or snagging on the wires.
The hardware used to hang the panel will depend on a few different factors – wall construction, stud availability, final panel weight, etc. Make sure you use appropriate hardware for your environment. In this case the final panel weighed less than 30 lbs, and the decision was made to use drywall anchor hooks and industrial hanging eye loops.
Now is a great time to get up and do some creative home improvement projects! Improve the acoustics of your home theater, living room, or home office… and have a cool new focal point for your space.