C, Education of complex issues requires a step by step process. Our experience with illustrating complex subjects tells us no more than one main item per video. If you try and define and explain the issues and then offer the next logical step as you have illustrated, people get confused. A confusion that translates into numerous phone calls and emails for me that takes away from my available time with customers. We will be doing a follow-up series on this topic in 2019 taking this concept to the next step and applying it to small room acoustics.

Thx but I asked for elaboration not a defense; that in no way answers my question. 4.5 feet what? 4.5 feet in what way? In what regard? 4.5 feet from the short walls? 4.5 feet tall? 4.5 feet is 1/4 of 18 yes, but you can't just apply that to NOTHING and call it a rule.

It has to do with particle velocity when the strength of the wavelength is at its weakest then theoretically it should be easier to stop with velocity based absorbers such as broadband panels etc...so to trap 60 hz fully you would need 54 inches of pink fluffy stuff to completely trap the wavelength. Limp mass absorbers or helmholtz helps in this situation, but by all means look into it dont use pieces of charcoal briquettes to tey and fix it at over a thousand dollars a pop. A sealed cabinet with hardboard or mass loaded vinyl does wonders if tou know the math so you can build them deep enough etc...

@@AcousticFields but which video shall i watch next? step by step is the right way to walk, but where shall we step next? we get lost in youtube randomness if you don't lead us a little bit, maybe you could PIN a comment with a link to the following subject? would be dope! much love and thanks for your work, really appreciate it!!

Glad it was helpful!

A, Building insulation will provide absorption in that frequency range. However, it does not provide the proper rates and levels for music and voice. The fibers are also lighter than air and can go through any fabric covering stretched over it. look at what those fibers are made of and then ask yourself if you want those in your bird's lungs and any other living thing in that room.

A, Thank you for your support. If you have a topic you wished covered in video format, let us know. Send to: info@acousticfields.com

Reales trustable info

sarath sankar Thank you, much appreciated.

Glad you enjoyed it!

Cover the screen with sound absorption or sound diffusion technology when listening to two channel.

A, Remember that waves oscillate through the air in cycles. Each wave has frequency and amplitude. If you look at a 18 8' wave individually, you would have to know the ending point of the wave as a result of boundary interference.

Assuming a constant 60hz wave, with an amplitude of 1 unit, and a wavelength of 18', at both 0' and 18' the wave will be at full amplitude (1). The wave will also be at full amplitude at 9' due to the way a sin wave works. 18' away will sound as loud as 0' away, as will 9'. These are maximum pressure modes for a single wave. This is assuming a perfect room with no absorption factors (couches... Cushons... Curtains... Etc.) and a single source of sound. After 18' the cycle repeats (with peak modes at 18', 27', 36') at a reduced amplitude due to a function of distance. The general rule is that, every doubling of distance, you lose 6db. That's not actually a lot. A subwoofer dumping 100db into a room at 60hz, at 1, 9 and 18 feet, will only be attenuated to 94db at 18, 27, 36 feet. As a general averaging rule. And unless you're playing single tones of music, harmonics play a large factor as well. A tone of 60hz, with harmonics at 120hz, 180hz, 240hz etc. will greatly complicate the dampening effect of distance. realtraps.com/art_rear_wall.htm

Hi Rene Giasson Thanks for the comment. Please complete this form on our site so I can better understand your room layout: www.acousticfields.com/free-acoustic-treatment-room-analysis-tell-us-about-your-room/ I will be better able to advise you with this information to examine. Thanks Dennis

F, Yes and no. Yes, placing the treatment at 1/4 wavelength distances is desirable for low performing absorption technologies, but not practical. It is best to use a technology that can absorb at 60 Hz. with the rates and levels you require regardless of where you place it.

@@AcousticFields Thank you for your reply! This is very helpful.

Neither. If you place them behind the screen, you attenuate 4 - 6 dB of sound energy from source. Never loose energy from source in order to manage it. Let source be source. In front of screen. I dont kknow what that means. Place them right and left of screen. Place them as close to screen as possible. Make sure the front edge of spaeker is ahead of the screen. Split the center channel signal into left center and right center.

A 500 Hz, issue can be resolved with a 2" think piece of open celled foam

You will have to use two dimensional diffusion on the rear wall due to proximity.

@@AcousticFields Should I build the rear diffusers with the same 282hz goal in mind? As I understand it, the target frequency depends on distance from listening position. With the rear diffusers being so close to that position would that number rise for the rear diffusers only?

C, let me know if you have any issues with your build. We have a whole DIY series of product build plans. www.acousticfields.com/product-category/d-i-y-acoustic-treatment/ You can buy the carbon and foam from us.

D, Shortest distance largest problems below 100 Hz.

R, There are many variables we must look at in room size and volume. Quarter wavelength, half wavelength, SPL levels, and a host of others. If you use full wavelength you have a good start towards ideal. The compromises from that ideal start point will determine the quality level we have to start with when we face the reality of small room acoustics.

S, You are welcome. If you have any topics you wish covered in this video format, send us email to info@acousticfields.com

J, Its physics. Sound travels at a certain speed. It also takes that speed and travels over distance. In small room acoustics its all about the distance the direct energy (straight line from speakers to ears) and the reflected energy from walls must travel before it reaches our ears. Its a balance between straight line energy (speaker) and reflected (room) energy. The "Golden Ratio" is a starting point towards that goal.

H, Why be concerned about speaker placement by dodging modes and looking for places where there is minimum pressure issues. Why not treat the room to minimize these issues throughout the room.

@@AcousticFields Thanks a lot!

I, There is plenty information on the net that you can use.

T, An 18' length would be best. Here is a different definition: Quarter-wavelength rule : If a wall is a node, then the nearest other node at any frequency will be 1/2(wavelength) away from the wall. Given this, the antinode is midway between those two points, or 1/4(wavelength) away from the wall, for any given frequency. So, for example, if you want to filter out 60Hz, divide 18’ (the wavelength of 60Hz) by 4 = 4’6" and hang a thin layer of frictional material (acoustic foam) at that distance from the wall(s) and floor and ceiling.

@@AcousticFields I really liked your video, It really opened up my eyes into how the acoustics works. But, here's another explanation from the wave sense. If you think of a sine wave, the positive peak is at the 90 degree point. That means that the highest amplitude or sound level will be at that point. If you want to quiet a room, then place the sound absorbent material at that 90 degree point and it will be the most effective in absorbing the sound. But, at the 45 degree point, the effectiveness of the sound absorption would be about fifty percent less. Thanks for making this video and it was a bit difficult to understand the directions of the wave in the drawings. Have a nice day.

K, No plans at the moment. Fill out the information in this link: www.acousticfields.com/free-room-analysis/

Rememeber the room does not care what you want. You must set up on the surface area that exhibits the frequency and amplitude issues that will best respond to treatment for the pressure issues. Along with this pressure consideration, you must then look to sidewall distance to manage primary, secondary, and tertiary reflections. The longer wall will satisfy the reflection issue but may not be the best pressure choice. Nothing in acoustics is easy.

@@AcousticFields i understand it not easy. Besides having s small room ( thats the biggest complaint for everyone) I purchased the diy kit made two bda and still i cant get or understand your concept. I challange you to make me a Believer. At this point all the money i spent on these BDA. Im starting not to have faith in what your saying

Hi Steve Morgan How are you? You are correct: 1132 / 30 = 34.40'. Now, here is a good question for you. What do you know of that will stop a sound wave of energy 34.40' long? Thanks Dennis

Diaphragmatic absorption device placed at 1/4 lenths along the wall?

What are you doing up so early? All nighter?

Steve Morgan I'm an early riser :)

Hi Steve Morgan I answered your question on the quarter wave length rule in greater detail in yesterdays Google Hangout. You can see the part where I answered your question here kzfaq.info/get/bejne/m7yqea2Kxs-Uo2Q.html. I also answered your question re: diaphragmatic absorber placement here kzfaq.info/get/bejne/p85-i8xlyNa6fYE.html I hope they help. Please let me know if you have any follow up questions I can help with. Thanks Dennis

All energy goes into the room. This 1/4 rule is showing what will fit and what will not.

B, I do not understand your question.

Acoustic Fields, sorry. I mean, do we have to find the frequency, don't we? Should we take that 60Hz frequency as an example or to be treated in any room?

B, The video is about quarter wavelength theory. You can use any frequency to illustrate.

Acoustic Fields, thank you for the answer!

Wavelengths come in sound and light. I would be interested in the color associated with the wavelength for light.

G, Yes, it is the distance that matters, not the unit of measurement.

Take the length of a 60 Hz. wavelength and compare it to an 8' ceiling height.