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I had a stupid cadburys ad - if their chocolate wasn't so bloody expensive I would buy it

😂😂😂

YOU STINK

Ha! Nicely played!

I see what you did there

Like the irony👌

Prop squared!

We appreciate the kind words!

Thank you for the support!

I wouldn't really call this video "demonstrations" as much as pictures and graphs.

Thanks!

Hey man, these are also extremely useful resources for studying the science of sound and recording if you're interested. kzfaq.infovideos kzfaq.info/love/N5UUY5P4IO1nCuQSfo-Uug kzfaq.info/love/SCwzZX29jTILlsP4MhjQvg

@@murphyalvin1893 thanks bud!

Same! (Fun fact, by the way, if you put a sub in and facing a corner with an obstruction (like cabinets) a few feet above it, the output is greatly increased throughout the room with fewer noticeable modes. It's the same with putting it under a desk or something like that. The modes even out to give more accurate output. Why do I know this? Testing! How does it work? Reverb I guess. I don't know.)

It still works in a similar way to a rectangular room at low frequencies, except for the length and width are identical every which way, meaning there is one very strong horizontal room mode right in the centre rather than many weaker ones.

I agree. Interesting video but no help whatsoever with setting up my hi fi system and in particular my sub woofers. well its back to good old trial and error for set up.

​@@johngarbutt just buy reputable bass traps, the more the better basically

@@johngarbutt I agree guys, there is some nice knowledge in here, but as for me and my setup, this doesn't really do much for me other than to play around with my own testing of acoustical materials and where place them in the room and then for the hours of listening tests as in A to B and back to A....

I think this video is marketing targeted to the very specialists you mention.

@@jasonLJ bassically

Round is the second worst geometry for a sound room after sphere. It hugely magnifies one or two frequencies beyond repair. I'd advise against it. Thanks, John Calder

To answer that, you have to know ahead of time where the speakers and subs will be placed before the room dimensions can be optimized. See Floyd Toole.

Thanks for your questions! Designing a room without parallel walls and non-parallel floor-ceiling geometry is a great partial solution, and many recording studios and high-end listening rooms do just that. But volume-based low frequency resonances (the same effect as blowing across the top of an empty bottle) will continue to be a problem. Also, due to room crossover, there are no diffusion treatments that will diffuse wavelengths longer than the room dimensions. The best solution to room modes and bass resonances will include combining effective low frequency absorbers with optimal room geometry design (as well as optimizing speaker placements).

@@johncalder8490 Thanks for the answer. Is there a program you use to determine optimal speaker placement and absorber placement in a given room? Also does room crossover cease to be a problem if your room is large enough to contain any anticipated bass wavelengths?

Hi Christian, thanks for your question! The room modes present in your room would depend on the room's dimensions - how many meters wide by length by height. Divide each dimension by 331.5 (speed of sound at 21 degrees C.) to give you the approximate modal frequencies for each axis (width, length, height). These "Axial Modes" are where your strongest mode additions and cancellations, depending on location in the room, will occur. We prefer to treat low-frequency (LF) modes with broadband absorption (we also prefer not to use the term "bass trap", as it has been widely misused). The combination of our two membrane LF absorbers work from about 45Hz to above 250Hz, fairly efficiently - the ratio of Curve Diffusor (each of which have a built-in LF absorption MLV membrane) and the CornerSorber (a dedicated LF corner membrane absorber) is about 3-4 Curves for each CornerSorber pair. When properly placed at 1/4-wavelength (room dimension) locations along each wall, Curves work very well to diminish modal energy. The CornerSorbers are placed in any room corner. I hope this helps! Thanks again!

Good question! There are differing views, of course. To control low frequencies in rooms, some people hold that the most-dense wall structures are best, some believe semi-resonant drywall structures are best. My own preference is for solid non-resonant walls because it is very difficult to predict how a drywall or other non-dense structure will behave after installation. The stud centers, number of screws and their tightness, whether multiple layers are used (and if Green Glue or similar is used), and other construction variables seem to argue in favor of solid, dense, and isolated walls, ceilings, and floors. Then accurately-tested and effective low-frequency absorbers should be used to mitigate room modes. IMHO. Thanks for asking!

Hi Lars, thanks for your comments. When trying to explain complex topics simply, it becomes necessary to under-explain deeper parts of the topic; the goal of our video isn't a PhD. level course in room acoustics, it is an awareness that there is a lot going on at low frequencies in a room and that with some knowledge, reasonable choices can be made to improve one's listening space. The point of the Kundt's Tube demonstration in the video is that below the resonant frequency of that particular dimension, the wavelengths are too long to fully develop and as a result, the usual methods of absorbing sound to reduce resonance energy, which are wavelength-dependent, are far less effective. Of course there is energy in the room from the speaker or instrument - the point is that to control resonances, different methods must be used. Many research resources use the terminology "velocity-based" and "pressure-based" - I decided to go with those terms. Yes - there are other LF absorber choices, but they all use much more space and can be unpredictable unless fully tested in an acoustics lab accurate down to the target frequencies. As for Helmholtz resonators, I have two problems with them: 1) as air conditions (temperature and humidity) in a room change, so too will the resonant frequencies (speed of sound varies by temp...) - will the Helmholtz resonator track those changes linearly? 2) More importantly, why would anyone add a new resonance to an existing resonance? Sound transients will be destructively affected. Well-designed and accurately-tested membrane low-frequency absorbers work, and if properly placed, remain the best choice to mitigate room modes, IMHO. There's a lot of misinformation and bad or non-existent "bass trap" specifications in the marketplace; there are test results from laboratories that cannot be accurate below 150-200 Hz due to Schroeder frequency test room size limitations. I'm confident that more information, even if condensed into short videos like this one, is helpful in making purchasing decisions, whether for our products or for other manufacturers. I wish the industry would get its' act together and insist on accurate product testing and specifications for these areas. Thanks again for your insightful comments! John

Below room crossover, using fiber-based absorbers is far less effective for absorbing low frequencies than using membrane LF absorbers. The room mode resonances which are responsible for room crossover cause much longer decay times at and around the modal frequencies, which also results in widely varying low frequency amplitudes at modal frequencies at different dimension-based locations around the room.

Speakers placed in the halfway point of any room will activate that respective low-frequency room mode less than at other locations. But yes, impractical in this example.