Archive for category Theater

Sonora® LFC – Low-Frequency Control Panel

Bass frequencies are difficult to control… and there is sometimes a tendency to overuse standard, broadband panels to try to absorb everything in order to get rid of that bass. However, this method is unbalanced and has the side-effect of leaving a room sounding muffled and boomy.

Why?

Physics! High frequencies are easier to absorb than low frequencies. So, when you ONLY use broadband absorbers, they easily remove the high frequencies and leave more of the lows. Overusing broadband absorption in a large performance space can be a disaster – leaving an environment lacking energy and feel – many describe this condition as a room sounding “dead.” (Not good!)

So how can you treat the boomy bass without killing your rooms with too much broadband absorption? Can you just take out the bass? Unfortunately, it is impossible to ONLY absorb the bass, but we can LIMIT the amount of high frequency energy that we absorb to balance out the response.

Acoustics First® presents… the Sonora® LFC – Low-Frequency control panel.

Looks like a standard Sonora® panel on the outside, but it’s completely different under that fabric!

The Sonora® LFC looks like a standard Sonora® Wall panel, but looks can be deceiving! At 4-1/8″ thick, it is virtually indistinguishable from a High-Impact Sonora® panel – however the interior structure of the LFC is optimized to attack the bass frequencies and smoothly roll off the high frequencies. Let’s take a closer look at the performance difference between the Sonora® LFC and the standard Sonora® panel.

Standard Sonora® 4″ Panel in red vs. the Sonora® LFC in blue.

When you look at the performance charts, you will notice that the standard 4″ Sonora® panel starts to “roll-off” in the lower frequencies below 125 Hz – it still absorbs them, just to a lesser degree. We designed the Sonora® LFC panel to focus on those frequencies below 125 Hz – while allowing the other treatments to handle the rest! This allows you to use fewer broadband panels, and still have some high-frequency energy for diffusers to spread around – thus creating a more balanced acoustic environment.

The Sonora® LFC is an engineered solution using the same high-performance materials as our other products, but combining them in a way that optimizes them for Low-Frequency Control – hence Sonora® LFC! The magic is in the way those materials are used.

The optimized construction of the Sonora® LFC Panel!

All of the materials used in an acoustic environment have a function – “Diffusers,” “Absorbers,” and “Bass Traps” are all general descriptors of product functions. Some diffusers are also Bass Traps. Some bass traps are also broadband absorbers. Some diffusers use absorption for amplitude grating. By combining a dampened, resonant trap with multi-density fiberglass, the Sonora® LFC focuses on making acoustic spaces more balanced. For controlling the bass without sucking the life out of a room, the LFC Panel is an outstanding tool for refined Low-Frequency Control!

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Quick Case Study: The Bank of NH Stage.

The Bank of New Hampshire Stage is multipurpose venue that hosts live performances, corporate events, movies as well as weddings.  The venue’s designers aimed for an acoustical environment that achieves a balanced and intimate atmosphere for their audience and performers.

The multipurpose space is convertible with different seating configurations for different types of events.

Sonora® Wall Panels and Sonora® Baffles were used to control specular reflections (echoes) and reduce overall reverberation down to a suitable level for the wide variety of BONH Stage shows and events. The results are absolutely stunning!

 

 

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ArtDiffusor® Model C and Model F – Similar, yet different.

Model C vs Model F

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.

Design.

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.

 

Performance

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.

Model F and C

Many critical listening environments use both the Model C and Model F to tune the diffusion in their space.

 

While the white Aeolians® on the back wall are the visual focal-point on in Big3 Studio A, look closely at the ceiling and you will notice a large array of black Model C’s and Model F’s. These help to intermix the diffusion of different frequencies in the large control room.

Due to their aesthetic and functional compatibility, many rooms benefit from using both.  Model C’s addressing the bulk of the Mid-range diffusion, and the Model F smoothing out the top end.

I hope that this highlights the unique properties of both the ArtDiffusor® Model C & ArtDiffusor® Model F – and helps to demystify their function and use in your space.

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Demystifying Acoustic Data: Part 2 – Test Material Mounting

For anyone new to the world of acoustics, there is a multitude of terms, coefficients and numbers that are thrown around.  This flood of information can seem intimidating, especially to beginners. In this series, acoustician Cameron Girard of Acoustics First® hopes to help you distinguish between what’s useful and what’s not.

Part 2: How Mounting in Testing Affects Sound Absorption Data

As I discussed in my previous article, the best way to compare the performance of sound absorbing panels is by referencing the Sound Absorption Coefficient (SAC) and Noise Reduction Coefficient (NRC). However, these coefficients are often used as marketing tools. Be on the lookout for companies that list absorption coefficients and NRCs without mention of a particular testing standard or mounting method. It’s vital to check for this information, as direct comparisons to competitors and other materials can only be made if their testing procedures are the same.

The sound absorption of a material that covers a flat surface not only depends on the physical qualities of the material but also on how the material is mounted during installation. The mountings specified in laboratory tests are intended to simulate conditions that exist in normal use, such as direct wall mounting and installation into a ceiling grid.

Many materials for treatment of walls or ceiling are tested using what is called Type ”A” mounting. Type ”A” mounting means the test specimen was placed directly on the test surface of the reverberation chamber. Lay-in ceiling tiles, on the other hand, are often tested using ”E400” mounting. The ”E” designates a sealed air space behind the specimen (simulating  the air gap between a dropped tile ceiling and the structural ceiling) and the number after the ”E” is the depth of the airspace in millimeters. The airspace behind the acoustic material affects the sound absorption by acting as a bass trap. The deeper the cavity behind the panels is, the lower the fundamental of the “trapped” frequencies will be.

To see what this look like in terms of actual numbers, let’s take a look at how different mounting methods effect the sound absorption coefficients of Acoustics First’s HiPer® Panel (a low-profile, composite absorber/diffuser panel).

Since the HiPer® Panel can be used effectively in multiple applications; we had it tested in accordance to the two most-common mounting procedures, Type E-400 and Type A. The results of the laboratory tests are as follows:

Product Info

Sound Absorption Coefficients

Product Name Thickness Mounting 125Hz 250Hz 500Hz 1kHz 2kHz 4kHz

NRC

1″ HiPer® Panel 1″ E-400 0.43 0.28 0.51 0.76 0.99 1.10 0.65
1″ HiPer® Panel 1″ A 0.09 0.28 0.78 0.75 0.94 0.85 0.70

 

As you can see from the chart, the sound absorption coefficient at 125 Hz varies greatly between E-400 mounting (SAC of .43) and Type-A mounting (SAC of .09). If mounting the HiPer® Panel in a ceiling grid, with a sizable airspace, you can expect significant low-frequency absorption, but mounting it on a wall (Type-A) will result in much less absorption at 125Hz.

Other mounting methods are available, but are not used as frequently. Here are some of the basic mounting designations (See ASTM E795 for more information.)

Type A mounting – Test specimen laid directly against the test surface (wall panel on drywall).

Type B mounting – Test specimen cemented directly against the test surface. Type B mounting is intended to simulate acoustical ceiling tiles or other sound-absorptive products adhered to a hard surface with an adhesive.

Type C Mounting—Test specimen comprising sound-absorptive material behind a perforated, expanded, open facing or other porous material.

Type D Mounting—Test specimen mounted on wood furring strips.

Type E Mounting—Test specimen mounted with an air space behind it (dropped tile ceiling).

As we’ve discussed, acoustical data can vary greatly depending on the mounting method used during testing. Acoustics First tries to include as much information about testing procedures as possible, because we feel an informed client makes the best client.

Contact Acoustics First for your all your sound control needs!

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DIY – Back Wall Diffuser Array/Bass Trap: Revisited

DIY - Diffuser Array/Bass Trap

DIY – Diffuser Array/Bass Trap

bass trap foam diffuser - sideThis month we thought we’d share a few Real-Life pictures of an idea we first introduced back in summer of 2013: The “Back Wall Diffuser Array/Bass Trap”.

Isolation Hanger

Isolation Hanger

This is the DIY project which incorporates our Art Diffusors®, Cutting Wedge® foam and a couple of isolation hangers into one large free-floating unit, which is acoustically decoupled from the wall.

This particular array was put together by a music producer/bass player for his home. As you can tell from the pics, the construction of this unit was executed beautifully and it’s very close to the original concept drawings.

It’s never too late to get started on your own DIY project.

Real World - DIY

Real World – DIY

Visit the Original DIY page to find out how to make your own. 

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