Good video and discussion. I read some earlier articles (maybe 15 yrs ago) where AR (acoustic Research) did some testing with fibreglass vs poly fill materials. They talked about how these materials affected compliance and attenuation characteristics. According to their observations in their AR3 and AR10 speaker cabinets the fibreglass had the effect of increasing compliance at frequencies below ~400 Hz This resulted in lowering the box resonance (increasing effective box size) while the poly fill had almost no effect on Fb. The fibreglass also had much more attenuation (dampening effect) in the same low frequency range than the poly fill which had almost no attenuation at low frequency. The article also said the poly fill attenuation improved at frequencies above about 400 Hz.
Using damping meterial is an important step. I used polyester pillow filling on my 2way bookshelf speakers and the difference is audible. Before using those it sounded harsh.
In my project, i've used combination of polyfill and material you've used for woofer enclosure to fine tune the Fb and combat standing waves. Works like a charm!
Yeah! Some people say taking a shower once in a while is superfluous! Damping might be seen as the last piece of a puzzle in speaker design but my experience showed me you can really fix some resonances and bad behavior by a judicious use of damping material. Great video!
3:30 i thought it was because stuffing adds mass to the volume of air in the box. higher mass of the volume is like having more weight on the end of a pendulum, having a bigger box is like having a longer swing arm. so the two can hit the same note of the helmholz resonator.
It would be great if you could make a video showing the importance on speaker cabinet bracing with examples as you did. You think bracing would help those bass reflex squiggles? And how can you tell if those squiggles on the impedance chart need to be addressed with damping or bracing? That would help a ton. Love your channel and would love to see more.
Excellent analysis of dampening material. I thought that secondary blip up on the impedance measurement was due to some minor coupling of the speaker when placed on the table although I have to admit I never tried holding it in free air when measuring with the Dayton unit which I also have.
Hey Mate :) love your Videos and came back to this one. I was wondering why youd damp the Walls at the bassreflex enclosure. Is Damping Walls not just for reducing the cabinet itself from Vibrating? If i want to cancel standing Waves in my cabinet i Need to put the damping material more towards the mid of the Speaker no?
I have two set-up...One dedicated for music ( with sealed sub with healvy poly fill stuff ) and for the movies ( ported sub obky with acoustic pyramid lining inside )
Should we conclude that sealed enclosure is superior to ported, PR, bandpass enclosures in that it allows for almost complete damping of the standing waves? What about making the box trapezoidal, i. e. one pair of walls is not parallel? As far as I understand, it doesn't eliminate modes, but it smears them out in frequency, reducing the energy at each particular frequency.
Yes, having an odd-shape box will help. The fewer parallel walls the better. Sealed boxes can be easily dampened as you simply stuff them, however, bass reflex boxes can also be dampened just as good. You just need to be more careful how you do it.
I bought dats yesterday and measured every speaker I have in house. I found that my sealed subwoofer has some resonance problems, because I can see little humps in the impedance graph. Maybe damping helps
i bought your courses on udemy,you are really as great teacher. am really interested in making speaker boxes but i dont want to dive too much into the technicalities. to make it easier for me,can you help me with the design and specifications.... while i do just the physical wood wooking.
Hello! I'm glad you like the courses. You can mail me or message me on udemy if you need help. I can help you out with subwoofer design. However, if you want to build 2-way/3-way speakers, you need to learn how to do the measurements and do it yourself. Without measurements, it can't be done.
Is there a link or a name of those dampening materials so that I could look at them and see the price if I want to use them and my next project?. I usually use a combination of the aforementioned egg crate looking foam with pillow stuffing but I'm definitely down to do something better if it's not expensive like those ones from parts Express where it's going to cost me 50 bucks to do a speaker with damping or dampening lol material
The cloth fiber is called recycled batting, maybe you can find a local source that supplies people that make quilts. Moving blankets are usually dirt cheap, sometimes free with a coupon at Harbor Freight, they are filled with recycled batting. For higher density foam, you could try carpet "rebond" pad, it's available in different weights with the higher weights being more expensive of course. If you could find a local carpet installer, they throw out tons of small pieces when doing an carpet installation.
@@mattgraham4340 I saw a video using vinyl floor tiles on walls, and thought Id try that and then dampening or some sort on top. I like the shredded denim looking stuff, but carpet padding will be nice as well. I usually use egg crate foam that is already used to save money, but I dont have any right now. Ive use memory foam as well in the past. I dont think pillow stuffing works well so I havent used that in a while
@@BARBELLS-AND-BUDS sticky back tiles is an interesting idea, but I'd have to see some kinda test data before I would be convinced. I guess they're thinking a cheap alternative to dynamat, but I would think of some roofing product before that. Then again, ice and water shield maybe just as expensive as off brand dynamat.
One question though. If you insert a ton of material inside, it will eat up some volume, right? So the box itself should ideally increase to compensate for loss of that volume? Or not?
Like I said in the video, the perceived volume of the box actually increases. I know it’s counterintuitive but that’s what happens. So for example a 10 liter box filled with damping material will act like a 11-14 liter empty box (depending on the type and quantity of the material).
@@AudioJudgement Hi, thanks, yes I know that from software simulations but as I can't explain why it happens it is still pretty weird conclusion to me. OK for lousy material I can somehow think of some explanation, but what if you stick that wide and dense thing onto enclosure walls (like in your bassreflex example), that is almost a solid material, does it still holds that there is no need to compensate?
It's not solid material, even though it looks like it. If I zoom in on the measurements (because they are pretty much identical), the resonant frequency of the box with the walls lined with damping material is lower by 0.2 Hz. Lower resonant frequency is a result of a larger volume box. Hopefully, to make things clear, I once heard an analogy that the sound waves have a hard time traveling through this damping stuff, so it takes longer to reach the box walls. Longer time to reach the walls simulates a larger box. However, the true explanation is much more nerdy and difficult to understand if you are not a physics guy.
@@AudioJudgementI've often wondered if damping material makes it behave like a bigger box, will a bigger box with no damping give you the same results ?
0:08 I've never heard of "damping material" As far as I know, dampening is the right way to describe this type of materials. If you check an online dictionary, e.g. the Cambridge dictionary, for "dampen" and "damp", it should be immediately obvious. There is not such thing as a verb "to damp" but only "to dampen" hence the right thing to say is "dampening material". So, I guess pleasing the audience and using English correctly are not always the same thing.
@@stephensandre5319 You obviously have a lot of time in your hands too. You probably suffer from lack of attention span too. In case you haven't noticed: a) He mentions that the reason of "correcting" his usage of the technical term is in response to other comments in his audience (not made by me) b) He obviously cares enough about his usage of English to mention that in his video so, in that respect, my comment above has a place.
ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nKNx7UFyIwA.html Good Morning sir. I have one confusion. How should we decide, that how much weight can be used for the added weight measurement. Like if we want to measure parameters for 3 inches, 5 or 8 inches or even 12 inches subwoofer ?
I disagree on the Damping a bass reflex. I built a pair of speakers filled with polyfill, a stringy fluffy material. The speakers are a dual 6.5 crossed over at 1.8KHz with a silk dome in the middle, a 3 inch port on the lower front of the 1.5 cu ft box. 35Hz fs in room empty box, 28Hz fs with about 25 ounces polyfill in each speaker. The fs numbers come from a dB meter and tone gen. I have never used the jean looking stuff.
@@shaolin95 😂 I will carpet pad that left over from jobs and I found a bunch of those foam squares that go on the floor of a gym and have used those. I didn't have to spend a dime.
