Bass traps 101 – your guide to corner bass trap placement power energy definition

###########

Frictional or porous absorbers (also called velocity absorbers) act on the velocity component of a sound wave. These are your mineral wool, fiberglass and studio foam type materials. They use friction to slow down the air particles that “ride” sound waves, converting kinetic energy into heat. gas bloating diarrhea Naturally, they absorb most efficiently where your sound wave-surfing particles have maximum velocity.

, Roxul Rockboard 60 /40 rockwool, OC 703 / 705 rigid fiberglass, Bonded Logic UltraTouch or acoustic foam) straddling the room corner. This creates an air gap. The sound velocity is minimum when touching the corner, but increases dramatically in the space in front of the corner. We’re exploiting this. The result is a simple corner bass absorber, sometimes called an “edge absorber”.

Make it fat: Another DIY approach is the “superchunk bass trap”. gaz 67 This is simply a “super” chunk, often over 2 feet thick, of low density (< 2.25 lb/ft³ or < 36 kg/m³) fibrous material (like low density mineral wool batt insulation, natural fibers like hemp, sheep wool or recycled cotton… or nasty, itchy, pink fluffy fiberglass insulation from hell).

In small room acoustics we use decay time (T30) to measure liveliness. T30 is a proxy for reverberation time (RT60), because small rooms don’t have true reverberation. Typical decay times in control rooms and critical listening rooms are 0.2 to 0.5 seconds. But, if you’re in a particularly small room (say, a bedroom), aim for 0.1 to 0.3 seconds. The smaller the room, the shorter the decay times should be.

You want to reduce the liveliness a bit further while treating early reflections and flutter echo, so you place additional broadband absorbers at your first reflection points on your sidewalls and ceiling, and on the wall behind you (you could alternatively use diffusion here). gas turbine Example products suitable for this are the Primacoustic FullTrap and RPG Modex Broadband.

In practice, additional broadband absorbing panels (and perhaps diffusion) would be applied as needed to achieve the desired level of liveliness. Critical listening rooms often pair a reflective (e.g., wood) floor with a highly absorptive ceiling. To prevent slap echo and flutter echo we usually want to avoid any large areas of bare wall or ceiling.

Many people simply use mid-high frequency absorption at reflection points, but broadband bass traps placed here can help reduce non-model peaks and nulls. They will also have some impact on room modes (primarily the axial modes, which are resonances that occur between two parallel surfaces like parallel sidewalls, or the floor and ceiling). A hanging ceiling cloud is typically used on the ceiling, but I’ve used broadband bass traps in the following examples.

• Diffusion on the back wall to prevent slapback and flutter echo, to increase clarity (by dispersing early reflections from the back wall), and to provide an increased sense of spaciousness. Diffusion should only be used here if there is sufficient space between the back wall and listening position. Otherwise, absorption is most suitable behind the listener.

The minimum listening distance for diffusion depends on the diffusers used, but in general at least 10 feet is desired to achieve a well defined initial time delay gap (ITDG) in critical listening or control rooms. In studio acoustics the ITDG is often called the initial signal delay gap (ISD gap). In digital reverb processors the ITDG is modeled using the “pre-delay time” parameter.

Room Ratios: The example room dimensions (12′ high x 16′-10″ wide x 19′-11″ long) are based on the height:width:length ratios 1:1.4:1.66. electricity and circuits These particular ‘room ratios’ were chosen because they produce a room with relatively evenly spaced low frequency modes. This gives the room a flatter bass response than similar sized rooms with less optimal ratios. Acoustically, cubic rooms have the worst ratios (1:1:1). 8 gases You may not be able to choose the size of your room… but if you can, avoid cubic rooms like the plague.

Saleem, good observation. Convex shapes are great. For a porous absorber type bass trap, which has maximum performance a quarter wavelength from the wall, convex shapes it increases the absorption at lower frequencies. Another big benefit is that if you add a reflective convex surface to the front of the bass trap, it’s a great surface for scattering sound.

Reflective concave shapes are generally avoided in acoustics as they focus the sound. Large concave shapes (like domes) are particularly terrible, causing extreme resonance. I was having a conversation a couple weeks ago with a world class acoustical engineer, and we happened to be sitting right at the focal point under a convex ceiling. electricity deregulation Even with our prior experience, were amazed at just how distracting it was to simply talk.

For a porous corner bass trap the approaches that make sense are to have it straddle the corner (triangle cross section), have a rectangular block that sits in the corner (square cross section), or have a convex surface or even a full cylinder that sits in the corner. A concave surface doesn’t make sense for a velocity activated (i.e. porous) absorber.

BTW there are huge opportunities for computational modelling in acoustics. We’re years behind the aeronautical / cfd / electromagnets world. My original background was electrical engineering (signal processing / control systems), and I went far off the standard path to get involved with computational acoustics. Most acoustical engineers don’t have experience with numerical methods, so there’s an opportunity there.

Option 1) Monitors as close as possible to the big windowed wall 1-2. When trying this out in the untreated room taking into account the 38% mixing position with one speaker, bass seemed to be there finally, but it seemed as if I had a little less mids. Let’s say, punchy bottom end, with articulate but perhaps a bit scattered highs. Not a lot of sweet spot margin when moving the listening position backwards, the bass null came fairly quickly, perhaps due to the bass bouncing back off the rear wall and nulling itself?

Option 2) Monitors as close as possible against wall 3-4. When trying this out at 38% mixing position, I had even more bass with more sweet spot margin, with a bit firmer sound, although perhaps a bit muddier too. (I have a bit of Eq on my monitors though so I could lower the bass and lessen the shelving). So less clarity but more solidity. Perhaps in this situation the bass just shoots through the windows on the back wall so they can’t bounce back and weaken themselves or create a null right behind me?