I searched the forum and didn’t find any results on this topic so I am starting a new thread on the subject. Has anyone here used the Sabine equation to treat their room?

I move frequently and for the last four months I have been struggling with the SQ in my new room. There have been new pieces of equipment that came into my system during this time which has added outlying variables.

My last room was the best I have experienced so I started retracing my steps with the development of that space and I recalled that the approach to treating my last room all started with the Sabine equation. After working through the different factors controlling what I was hearing I knew what frequencies were problematic, and then treated accordingly.

This lead me to Acoustic Field’s diaphragmatic broadband absorption technology, and I implemented four of their BDA’s along with quadratic diffusion. A little tweaking on the placement and it was nothing short of stunning sound.

Fast forward to now and after four months of not liking what I’m hearing and my system almost becoming an unlikable step-child, I feel like an idiot for not recognizing that I am treating my current space the same as my old space. So I took a few hours and worked through the Sabine equation for my new space and “theoretically” have solved my problem.

It turns out the BDA’s that were so critical to my last space are not only not necessary in my current space but detracting from the SQ. Out they went and the sound improved right there. I dropped my “sub” (Lii W-15’s) crossover point to 65hz and things improved again.

I have room modes haunting me from about 120-480hz. so the next step is some membrane absorber treatment targeting that range. Fairly simple to address.  

Has anyone else used this approach? It seems logical yet uncommmon. there are so many panels and diffusers on the market but I dont see much in people's implementation other than the stereotypical "absorbers at reflection points and diffusors on thw front and back wall". A lot of people's gear choices and recommendations come from what sounds good in their space and if their space is off kilter then their experiences with equipment will be too.

The Sabine equation determines reverberation time at different frequencies across the spectrum. The problem with many treatments is that they are only (or most) effective at certain frequencies, or some are broad spectrum, like the BDA’s, but our rooms often only need specific bands treated.

GS, I won’t pretend to be an expert on the Sabine equation but I will share what I know.  If the audiophile were to analyze their room and plot the reverb times of a range of frequencies (32, 67, 125, 250, 500, 1000, 2000, 4000 hz) this would result in a reverb time curve.  The purpose of Sabine equation attempts to flatten that curve where there are peaks.
How low the listener wants to go with their reverb times is subjective.  

There is a wide range of listener’s objectives.  On one end there are folks that tape foam to their walls haphazardly, and on the other end those that have a money-is-no-barrier approach and treat every surface with exotic sound products.  What a listener believes is good is highly subjective, too.  What is “good” or “best” is only better within their own personal experience, frame of reference, and preferences.

What I think is special about the Sabine approach is that it focuses a listeners treatment exactly where it is needed by quantitatively reducing RT60 at specific frequencies where problems exist.  Especially when people are new to critical listening, short on space and trying to multi-task the purpose of their room, and/or share a space with significant others that may limit the amount or extent of room treatment, this “maximize the efficiency of your treatment” approach can be important; and I’ll bet that a majority of the forum membership falls into one of these categories.

Sorry, that’s kind of a long winded way to respond.  I haven’t read an “optimal” RT60 time that the listener should flatten the curve to.  Some sources suggest under 1 second, while 500ms is probably a good balance between being dead and just lively enough for me.  I appreciate natural materials in my spaces and the timbre of the surfaces outside of dampening so I don’t personally want to deaden a room.

Yes, BDA stands for broadband diaphragmatic absorption.  The Acoustic Fields BDA’s are great in some situations, like the common American stick-built home.  As they state, they are broadband, with a relatively flat Sabine coefficient across the spectrum.  So if you start with a blank space and want to treat consistently these are a good start, and worked well in my previous space.  The carbon Dennis uses really is only for mass loading, to get a sabine coefficient at low frequencies that is similar to the coefficient at other octaves; it has no special acoustic talents beyond that.  It’s actually a pretty primitive product in that regard, but great for being effective and marketable.  In my current space my walls and floors already have a huge amount of mass loading so treating below 100hz is unnecessary.  Similarly, the amount of natural treatment, between art, carpet, and furnishings makes treatment above 1khz unnecessary.  Working through the equation, I really just need some help between 125 and 500 hz, with a focused peak at 250hz.  And the Sabine equation tells me exactly how many square feet of treatment I need to do that.  So rather than fill my room with different products to reduce everything I can just focus on one diaphragmatic absorber focused on 250hz that offers a curve of its own from 125 to 500, I maximize the effectiveness of my treatment and minimize my investment.  

I should also say that RT60 time isn't the be-all end-all way to treat a room.  Other things, such as quadratic diffusion, have made a dramatic improvement in my listening experience too.

As CAJames would say, YMMV and all that.