Safety note: protective measures should be taken when working with mineral fibers like rockwool or fiberglass. They're extremely harmful to the respiratory system and more than annoying to get embedded in your skin.
Dude... there are is no other way for me to say it.... I love you! Your channel is pure gold. Very inspiring, clean image, beautiful animation, fluent speech, you know what you are talking about, not too fast not too slow, easy to fallow, simply awesome. What on earth could I ask for more? Well.... that you were my neighbour. 😁
Peaks and dips in the response can be corrected in the DSP but the ringing is still there. Treating is the best way to fix this problem. Btw, nice presentation.
Rock wool is amazing! Recently rehabbed an attic room for my daughter, and part of the room had a seciton cut out where the bathroom/shower is. I bought a pack of rock wool, and threw it in the wall, and also used thicket drywall (not worth it! thick drywall is waaaay to hard to work with), and the noise difference is incredible! I mean, you already have backer board, tile, grout, and drywall, but previously you could hear every drop of watter hitting the floor in there. The slightest hum, and you could hear it in that room. Now with the rock wool, there is a little bit of a running water noise from the pipe in the wall; But that is it! Unless you are singing your heart out, nobody is going to hear anything that is going on in there. Ironically, go to my son's room, which also shares a wall with the same bathroom, but the room part, not the shower, and you can hear everything. His side only has some thin drywall in the bathroom side, and some 70's era 'wood' pannelling, but it is pretty bad. Guess I know what I'll be doing next! Thankfully I already did most of his room, so it wont be the whole room. Pretty much just this one wall... and maybe move a cut-in notch to make a real closet space in there.
Hmmmm, Rockwool...... itchy stuff, gritty on the teeth if your unlucky enough to breath it in. If your thinking of using this stuff in a high power reflex design/port, cover it in fabric b4 installing (like a pillow) High power drivers can break up the material causing particles to get pushed out of the port and into your room. Covering it with fabric will at least contain any breakup. Spraying the cut ends with hairspray was another trick I've seen.
A lot of the studio absorbers use plastic sheeting in addition to fabric to contain the rockwool. The dust is notorious, and is a significant concern as a panel reaches an age of a few decades. This is one of the reasons why Owens Corning resin-fiberglass panels are popular in the USA.
Actually your completely wrong at least in EU, they tested the health concerns of breathing around them as workers were installing them in many buildings and results were that no health concers after 5 years.
Quite a few errors in this one: 1. In room measurements are a very poor way to look at enclosure related issues. 2. Enclosure issues need to be separated into two categories....panel resonance, and internal standing waves. 3. The wavelength of 51Hz is 22 feet..your box is roughly 2.5 to 3 feet in it's longest dimension (judging by the table it's sitting beside) There is NO WAY for a standing wave to develop when the the internal size is only 1/10th or so of the supposed frequency. It is *theoretically* possible for the panel to develop a resonance, but that would have to be a very very poorly braced box. And while that box had no sides braced against the opposite sides, the ribbing should provide pretty substantial strength. 4. Two inch rock wool will not provide any significant absorption down that low. Anechoic chambers are build with very large wedges to provide enough wall absorption to minimize any room boundary caused errors....those wedges would have to be 1/4 wavelength thick or more...so roughly 5.5 feet. Enclosure issues are much easier to diagnose through impedance measurements. Either type would show up as a bump in the impedance or a wobble in the phase of the impedance. If you're going to try to diagnose these sorts of issues with response measurements use the ground plane technique.
+1 However, it is also important to note that wave propagation within a box a low frequencies is fairly chaotic, and significantly reducing the reflectivity of the surfaces will produce a complex set of changes to the acoustic response. Also many studies of rockwool panels have shown that under some circumstances due they can reach lower than expected from gas-flow impedance models, possibly due to pressures at the boundary causing the fibers to flex. It's something that has been puzzling acousticians for a while, and it's hard to precisely predict what the installation of rockwool panels will do without measuring in real world experiments.
@@weareallbeingwatched4602 At higher frequencies the impacts can be strong sure...but that's a 30" tall box. The biggest difference in the measurements was at ~50Hz. We're talking 1/10'th of a wavelength, so there's no real wave propagation at that point, but pressurization. I'm well aware of the modeling MJK, Backman and others have done on the impact of stuffing, these results fly right in the face of Backman's most recent stuffing/FEM modeling paper he did while still at Genelec. Basically it's a false premise that that issue can be measured in room, it's a false premise that the fix did anything substantial at those frequencies unless that box is literally a floppy mess (and hot gluing rock wool will not add substantial damping to those walls) and a box that size should never have an issue at 50Hz anyway. If it were 5.5 or 11 feet tall sure...but that box is less than 36" That should have been shown as change in system Q in an impedance measurement and an elimination in any impedance wiggle up higher in frequency. I would estimate (again without knowing the exact enclosure dimension) that it's a vertical internal standing wave that doesn't form until ~225hz or so. Even then he'd have to do a double layer of 2" rockwool since the performance of the stuff starts to drop even with the higher density foam between 250 and 500Hz pretty significantly.
It would be nice to see further investigation on the effects of cabinet bracing and constrained layer damping. And also a comparison with plain old industrial grey felt.
I am a speaker guy myself, but I am also *extremely* poor money-wise, barely able to (usually) pay my rent on time each month, (NOT rn though, because of the current, Spring 2020 pandemic and no work), so I can ONLY afford to design speakers and subs and other stuff on *paper* and with a calculator, and I can only afford to work with cheap speakers and stuff I find in the thrift stores or used... I really WISH I had all of that "high-tech" gear and measuring equipment that you have there! My GOD, the totally EPIC and *groundbreaking* speaker designs that I could develop, test and build with all of that computer and pro audio stuff is only *imaginable* to me, but I certainly would get my use out of all of that kind of stuff IF I had any access to it! WOW!... I really LOVE watching videos like this about sound and speakers and acoustics because that is MY "nerdy" passion too, you have NO idea! I always enjoy your videos man! I just wish I knew you personally and lived in the same city as you, so I could visit and talk speakers and electronic stuff with you for hours on end!
@@HexiBase I'd wager a guess the difference would be negligable, and most likely not worth the price incurred by having some sort of acoustics stamp. Anyhow, I was excited for this video but I wanted to learn about how different angles effect the frequency graph. I saw an audiophile video with someone touting "defractionless" speakers and I could not find much information surrounding that. Sure it's certainly bogus, but a rectangle prism I'd imagine is hardly near our best option. Please drop some knowledge if you can.
Yea man, Rockwool RW3 or RWA45 is standard mass produced insulation stuff. It is designed and rated for acoustic insulation as well as thermal. In the USA a lot of recording studios prefer Owens Corning resin fiberglass panels www.owenscorning.com/insulation/products/type706andtype707seriesfiberglasinsulationboards , because they are less prone to shedding the horrid rockwool dust.
Regular fiberglass pink is not much different from egg crate insulation. If you manage to find stuff labeled as "Quiet Zone" or some thing like that, it will be superior to regular pink. It is however quite a bit more expensive, usually about twice the price. And it is usually not as good as mineral wool, but is often somewhat cheaper as well. So you have some gradient of trade off vs performance. For my low power system I went with mineral wool after trying many other things. In my situation it was the only thing that worked to my satisfaction. And this is also keeping in mind the room is purpose built.
A hamster crawled through the bass reflex port of a friends subwoofer, and could not get out again. So he lifted the woofer and shaked it to get the hamster out. That did not work, so he had to dismantle it to get the hamster, which had been shaken around in rock wool. It died a few days later, and his daughters got sad. As for the good sound absorption. I think this is due to rocks higher density, so the fibers resist moving with the sound waves. And there should also be optimal thicknesses of the fibers, matching air diffusion distances at different frequencies.
4:31 It would be awesome to see a plot of the light blue curve minus the yellow curve, or perhaps the absolute value of the difference, if the program you are using allows it.
I like the results shown in the video but I would have preferred a deeper look at what enclosure resonances actually are and where they stem from. You almost started to dig deep with the look at pressure response inside of an enclosure but just kinda left it hanging there. The thumbnail had me thinking you were going to talk about the effect (or lack there of) of adding 45 degree corners. Talking about bracing enclosure panels would fit nicely in a longer more in depth video about enclosure/panel resonances. The effect of a double baffle vs dowel vs I-beam style bracing would be fantastic. Keep up the great work!
I use polly-fill myself, I like it's affect better than foam. But I've never measured the before and after, you've definitely got me wondering about that wool stuff though! That's an impressive result for sure.
Can you please make a tutorial, of how to make correct time alignment messurements, and how to eq properly. there is'nt much info about that. thanks from the netherlands
Actually mild steel sheet with dynamat could work as a pretty effective membrane absorber if correctly designed. Possibly with some holes in it, and an airspace behind it.
The great thing about the interesting hobby speaker building is that each detail of it can be a whole science on its own. You can produce different results depending not only on the type of material you use but also on how the material is distributed inside the box. And iif you start to combine different stuffing materials, try several styles of bracing and use separate absorber chambers inside you can experiment for years!
hope to see lots of videos coming up from you Pete these days, lets have some positive stuff coming up out of this quarentine disaster....we need more content, in a couple of weeks ill be running out of good movies and series...lol
Have you ever looked into mass-loading (sand-filled walls, inner walls lined with dynamat between the cabinet & rockwool), or constrained layer damping & its affects on cabinet construction/resonance?
I'd recommend using a cheap machete from harbor freight, just make sure to keep it sharp. It'll slice through the stuff from orange or blue cleanly and with minimum effort. I've been stuffing the walls of my house with the stuff mostly from blue, it's slightly thicker and denser, but I never considered using it in a speaker box. I have a project coming that it may be useful in. Thanks for the tip!
I would love to see a video or series of video on room correction and bass management using miniDSP and mic and rew. Not able to find any online wonder how people missed this is the core. I won’t mind to pay for such a content
You should try the fxtreme DB450 DSP amp! it is wayy better then any other amp boards, and it has literally everything already build in, bluetooth, DSP, 4 channels (2 channels bridged) and even a freakin step up booster! so basically a AIO lol.... i already bought it a few weeks ago and it really is the best amp money can buy
The difficulty of mapping semi-conductive elements within an enclosure is the reason why the aperiodic enclosure design was omitted from the original thiele & small papers on parametric modelling of enclosures. In all honesty that rockwool isn't thick enough to really influence subwoofer frequencies, and if you look at many of the commercial sealed cabinet designs from pro audio, it is typical to fully-fill the cabinet with polyester wadding in order to achieve a relevant level of resonance damping. I would expect that a box entirely filled with rockwool would be quite successful in reducing resonances, but might be difficult to model. Have a look at this BBC research paper on the subject of wideband rockwool absorbers for reference: www.bbc.co.uk/rd/publications/rdreport_1992_11 Also for reference note that low frequency absorption is not generally achieved using rockwool panels, but instead by using perforated membranes: www.bbc.co.uk/rd/publications/rdreport_1971_15 There is a lot to be said for solving the problems of speaker cabinets using the same acoustics toolbox and materials palette as is used for an architectural scale space, although the general assumption has been that speaker cabinets and smaller rooms do not have the required volumes required for the absorption of low frequencies using foam/mineral wool.
I agree with you, the wavelenght of low frequency are to long to trying to damping it with any absorbers materials, the most important in cabinet for low frequency driver is eigenmodes of the cabinet himself. Some commercial brands just put absorbers in there subwoofer to make it look great when customers look inside, but most of the time it's totaly pointless. It need several meters of foam absorber to start damping 50Hz who has 6.86 meters wavelenght. Sorry for my English :D Just a thought: Maybe the mineral wool dont absorved this 50Hz resonance, it slow down the air in the cabinet at a specific location and calm down a cabinet eigenmode around 50Hz. if it really absorved the 50Hz resonance so why it didnt absorved the 80Hz resonance and all the little dips after 100Hz which got a shorter wavelenght, in theory it's easyer to absorve a shorter wavelenght. just a thought btw.
@@Jean-Triphase well, suffice to say that almost all decent quality PA cabinets have fairly thick lagging inside them - usually wool felt of some sort. The dynamics of the system and how it pressurises and depressurises - and also how wave fronts propagate within the cabinet - the general assumption is that supplying enough dampening material at the boundary thus removing the ability of the cabinet's internal resonances to result from unwanted reflections and standing waves / comb filtering is appropriate. For a subwoofer the effects are going to be negligible, whereas building a 4ft deep box/tube entirely filled with rockwool very likely would produce a totally different but hard to model enclosure. This would allow both the exploration of the more detailed sorts of analysis of exactly what rockwool does, and also would very likely produce a resonance-free and back-wave free enclosure which might outperform a sealed cabinet in terms of frequency response if not efficiency. One question is... what is the speed of sound in rockwool?
Yes PA Speaker or even Hifi, Pro monitoring for the absorve >500Hz. Braces is used for control 500Hz. I still maintains Wool is nearly pointless for absorbing frequency resonance inside a subwoofer cabinet.
@@Jean-Triphase well, regarding frequencies, depends on the size of the box, really. The problem is that if you over-fill a cabinet, you start changing the speed of sound. That is the "secret sauce" and patented method in PMC's transmission lines.
foam, rockwool or any other similar stuff dont´t have any important effect on bass region, under 200Hz fibers do not absorb or dissipate nothing. When you need to absorb or dissipate energy in that frequency range, vibrating panels are used in conjunction with some absorption (membrane resonator), or bass traps that depend on the dimensions of the wavelength (1/4 lambda) or helmholtz resonators. Foam or other similar stuff inside box absorb only the highest resonance internal modes. The effective response on bass depends on box dimensions (due to refraction, 100-400hz) or on main modes of the room. Below 100Hz, in a normal room (without very deep bass traps, or any treatment in that region), the frecuency response is heavily influenced by the resonant modes of the room. And the equalization does not have much effect, because once these resonance modes are activated in the room, they are "hung", ringing for a while once the sound source stops emitting. Waterfall plots are very helpful to see what happens in the room on extreme bass
Do you have any videos on box geometry, as in what the optimal solid would be? Such as a cube vs. a sphere, maybe even comparisons with some other solids such as the other platonics, or the more easier to construct archimedian and catalan solids; I'm also somewhat curious about how a toroidal enclosure would theoretically work. I know this would only really be demonstrated with air velocity/pressure simulations, as there's no real way to make a truly spherical enclosure easily, and finding a way to glue together a large solid that isn't a cube could be fairly difficult. I'm just more curious as to how deviation from 90 degree corners would affect output; say, would a tetrahedron be better or worse, or would an octahedron be better or worse, then so on until we get to something that's too difficult to manufacture, like high face count solids and spheres.
If you put a mesh separator in the middle. Then put an hinged lid on the top. Make sure to install a air tight gasket, along with a latch strong enough to keep it sealed. You then have a (can’t combine the words together to make sense) laundry basket/subwoofer.
An SQ competitor once told me similar results were had by using recycled denim carpet underlayment. I tried it on his suggestion. Seemed to work really well at a fraction of the cost of the mineral wool.
Glass wool has been used in older west German studio monitors with lots of success. I've used rockwool in old Dali towers myself and it not only corrected peaks and valleys but lowered the bottom end a bit, too. Though that's a reflex box.
Great video! At 2.37 you use a spray gun. Is it glue to mount the boards in the cabinet or a varnish that will bind the stone fibers in the Rockwool board? Dust can damage the speaker coil. Know that Rockwool has boards that have a cloth on one side to stop the dust in the board. Take a look at their acoustic range, next time. Rockfon is the brand. There, the boards are covered on one side of canvas or acoustic paint.
At time approx 1:25 you show cabinet internal pressure simulations-what software is being used here? Assume more "price friendly" than Comsol?.... Cheers.
Are you calculating the sectional density and volume of the dampening material for wave reverb delay /phase delay to impact resonance vs just using a more efficient enclosure ?
@HexiBase great job bro! & my box is like the 74 litter but it is powered and has a rectangular vent that I don't know if I should close or leave open? I just watche movies if that helps. lol
I use a product that is a dense CCF. It is about 3/16-1/4" thick. Bought a 100' x 4' roll at a yard sale, there isn't a branding on it. I haven't modelled its response, but it did noticable smooth out the perceived sound. Power handling increased, proportionate to the number of surfaces inside the enclosure (18mm Lauan plywood) that were treated with that CCF. The sub acts as if it is mass loaded. Very intriguing. Thanks for the visual representation of + and - pressures. I look forward to your next video.
Have you ever completely filled the box inside with poly fill or other absorbing/ damping material? What was the results? ..or what your recomendactions about this? Thank you!
Is the enclosure made with mdf if so I used to install car audio for 15 years. Mdf is pourers meaning it’s compressed wood that air can still penetrate the material. When I design a box I fibre glass the inside and then paint the inside with bitchinum paint which builders use on the roof. Then apply the sound proof . Amazing results. I’ll send you pictures of my installation which I’m doing to my van
I always enjoy your content. Luckily most of the car audio enclosures I built (1980's to current, LOL)had at least 1 angled back wall or speaker face. I did experiment with different methods to reduce standing back waves back then. I had a enclosure design I was gifted in the early 90's that I can only remember a few details about. I'd like to see if you can help me identify what it was. Keep the videos coming.
So when you add the dense mineral wool the box volume is reduced. This test compared to the volume of the empty box would not be the same test correct?
Out of curiosity, what would the response be on an enclosure like this if you added a small port to it with the mineral wool? Also how would a rounded enclosure effect the sound and response of the sub? Meaning the inside of the enclosure being egg shaped.
@@HexiBase I've seen other videos of yours with calculated frequency responses for all types of enclosures. I use WinISD and only have a few options for enclosures. How would you calculate more advanced responses?
Sound insulation is not necessarily a good sound absorber. Concrete is an example of the former only. In a speaker box you want something soft enough to deform at the relevant frequencies and SPL to re-release the energy slowly. I would guess that rockwool suffers the same problem as foam. Too firm. With polyester the apparent volume of the box can even be increased.
@@michaelpiotrowicz6100 I think you would do well to do some reading on the speculation about how exactly rockwool is absorbing sound. It is primarily gas flow impedance (also termed air flow resistivity), but also relies on qualities such as tortuosity and porosity (coupled flow nightmare). It is not a simple matter. Rockwool works, of that much we are sure, and most of its effects can be modelled simply by its ability to impede gas flow. Here is some surface to start scratching: resource.isvr.soton.ac.uk/staff/pubs/pubs47.htm the paper by fahy and Thomson on the coupling of perforated/porous solid surfaces to air is worth a read.
@@weareallbeingwatched4602 thanks for that. Some experimental literature that you might find interesting, and which is consistent with my experience, is available to read here sound-au.com/articles/boxstuff.htm
What about the common poly fill? If planning for the wool, does it eat up some air space? In other words, build a little bit bigger enclosure to get your net volume after the wool? I usually do minimum 1" walls with overkill bracing. Then loosely fill with poly.
Seems like a very expensive way to smooth out the response. You did not state how much reduction/improvement you've got (in terms of db), and whether the wool affected efficiency, And whether you've actually heard the difference, especially with music. Personally, I'd first modify the internal geometry by getting rid of the 90° corners and filling the box with a cheaper alternative.
Was it worth the time and money to switch to the Mineral Wool? To me there was little effect between the different insulation types. It may change the graph some but can you actually hear the changes?
Can you do a dedicated video on the bass reflex band pass box, the one where it ports into another chamber I would really like to build one but can’t find any more information on it besides the uncommon box video you made
What if you change the internal shape? If you stick to the same size cabinet, what happens if there are no parallell walls? If you curve the rear wall, and the side wall? Or any other shape you might fancy that might help sound wave reflection? For years I've been having this in the back of my head without finding the time to test it out, and also I don't have any test equipment or skills how to use such tools, so I would have to rely on my ears and only them, and I am not sure they are good enough to hear any difference. Have you ever tested this out in real life?
@Hexibase just wondering if you have ever dabbled with some Isometric Pressure Speaker drivers? Vifa makes some good ones. I have the Vifa Helsinki and its one of the best sounding Bluetooth speakers i have ever listened to. I bet you you could create a kick ass Isometric Pressure Speaker set up with your vast sound knowledge.
i think it mostly refers to trying to fix the natural destructive nodes through dsp instead of actually fixing the room/speaker positions/speaker cabs. if the problem is severe, you're just going to be adding a lot of distortion because the amp will clip first at those huge spikes, and the speaker will distort since it is still working harder, but it will be naturally muted due to the destructive node cancellations. i personally have this problem, (at around 120hz for me) and my audio suffers because of it, mainly classical music which has huge dynamic range (and imo, unnecessary). i'm not a perfectionist, and because it works well enough as it is, i haven't bothered fixing it.
I ordered a mini dsp c6×12 for my car but I now need to buy a Windows 10 laptop to be able to use it lol! Look forward to any videos on using the minidsp products and tuning
How much the volume the insulations occupies inside the box? would be interesting to test the same real volume in an enclosure bigger enough to compensate the 2in thinckness of the rockwool
Can I do a push pull isobaric with a front facing subwoofer and a down firing subwoofer firing into the enclosure from the top at a 90 degree angle from front subwoofer?
Hi there, I just build a subwoofer with a Skar audio enclosure and a 10" Electrovoice Subwoofer driver, it produces excessive vibration all over the house, so I tried to isolate it by placing the subwoofer over a piece of foam and it worked 75%, do you have an idea on how can I can reduce more of the vibration? Thanks in advance...
The 360 slideshot was fantastic. I sure hope they appreciated the visual interpretation of pressure waves interacting with each other over time.
Agreed. @Hexibase this was terrifically shot and edited. Pro stuff.
Yess!! that was a nice touch, I am still wondering, how did you manage to pull it off!
Sure was, in fact, I have to wonder exactly how he did that.
Always delivering nothing less than quality videos and information! Keep it up, HexiBase!
Can't wait for the DSP video :)
Safety note: protective measures should be taken when working with mineral fibers like rockwool or fiberglass. They're extremely harmful to the respiratory system and more than annoying to get embedded in your skin.
Rockwool rash... bad on finger... worse on a lung.
That's why I use Open Foam and Polyester Batting. Also the other stuff can cause Small loose fibers to get into your Speaker drivers and damage them.
Dude... there are is no other way for me to say it....
I love you!
Your channel is pure gold.
Very inspiring, clean image, beautiful animation, fluent speech, you know what you are talking about, not too fast not too slow, easy to fallow, simply awesome.
What on earth could I ask for more? Well.... that you were my neighbour. 😁
Peaks and dips in the response can be corrected in the DSP but the ringing is still there. Treating is the best way to fix this problem. Btw, nice presentation.
Rock wool is amazing!
Recently rehabbed an attic room for my daughter, and part of the room had a seciton cut out where the bathroom/shower is. I bought a pack of rock wool, and threw it in the wall, and also used thicket drywall (not worth it! thick drywall is waaaay to hard to work with), and the noise difference is incredible! I mean, you already have backer board, tile, grout, and drywall, but previously you could hear every drop of watter hitting the floor in there. The slightest hum, and you could hear it in that room. Now with the rock wool, there is a little bit of a running water noise from the pipe in the wall; But that is it! Unless you are singing your heart out, nobody is going to hear anything that is going on in there. Ironically, go to my son's room, which also shares a wall with the same bathroom, but the room part, not the shower, and you can hear everything. His side only has some thin drywall in the bathroom side, and some 70's era 'wood' pannelling, but it is pretty bad. Guess I know what I'll be doing next! Thankfully I already did most of his room, so it wont be the whole room. Pretty much just this one wall... and maybe move a cut-in notch to make a real closet space in there.
Hmmmm, Rockwool...... itchy stuff, gritty on the teeth if your unlucky enough to breath it in. If your thinking of using this stuff in a high power reflex design/port, cover it in fabric b4 installing (like a pillow) High power drivers can break up the material causing particles to get pushed out of the port and into your room. Covering it with fabric will at least contain any breakup.
Spraying the cut ends with hairspray was another trick I've seen.
@nate0
A lot of the studio absorbers use plastic sheeting in addition to fabric to contain the rockwool. The dust is notorious, and is a significant concern as a panel reaches an age of a few decades.
This is one of the reasons why Owens Corning resin-fiberglass panels are popular in the USA.
nate0 > Totally agree with you, thought I'd just add the covering part incase some people didn't know.
Actually your completely wrong at least in EU, they tested the health concerns of breathing around them as workers were installing them in many buildings and results were that no health concers after 5 years.
Quite a few errors in this one:
1. In room measurements are a very poor way to look at enclosure related issues.
2. Enclosure issues need to be separated into two categories....panel resonance, and internal standing waves.
3. The wavelength of 51Hz is 22 feet..your box is roughly 2.5 to 3 feet in it's longest dimension (judging by the table it's sitting beside) There is NO WAY for a standing wave to develop when the the internal size is only 1/10th or so of the supposed frequency. It is *theoretically* possible for the panel to develop a resonance, but that would have to be a very very poorly braced box. And while that box had no sides braced against the opposite sides, the ribbing should provide pretty substantial strength.
4. Two inch rock wool will not provide any significant absorption down that low. Anechoic chambers are build with very large wedges to provide enough wall absorption to minimize any room boundary caused errors....those wedges would have to be 1/4 wavelength thick or more...so roughly 5.5 feet.
Enclosure issues are much easier to diagnose through impedance measurements. Either type would show up as a bump in the impedance or a wobble in the phase of the impedance.
If you're going to try to diagnose these sorts of issues with response measurements use the ground plane technique.
+1
However, it is also important to note that wave propagation within a box a low frequencies is fairly chaotic, and significantly reducing the reflectivity of the surfaces will produce a complex set of changes to the acoustic response. Also many studies of rockwool panels have shown that under some circumstances due they can reach lower than expected from gas-flow impedance models, possibly due to pressures at the boundary causing the fibers to flex. It's something that has been puzzling acousticians for a while, and it's hard to precisely predict what the installation of rockwool panels will do without measuring in real world experiments.
@@weareallbeingwatched4602 At higher frequencies the impacts can be strong sure...but that's a 30" tall box. The biggest difference in the measurements was at ~50Hz. We're talking 1/10'th of a wavelength, so there's no real wave propagation at that point, but pressurization. I'm well aware of the modeling MJK, Backman and others have done on the impact of stuffing, these results fly right in the face of Backman's most recent stuffing/FEM modeling paper he did while still at Genelec. Basically it's a false premise that that issue can be measured in room, it's a false premise that the fix did anything substantial at those frequencies unless that box is literally a floppy mess (and hot gluing rock wool will not add substantial damping to those walls) and a box that size should never have an issue at 50Hz anyway. If it were 5.5 or 11 feet tall sure...but that box is less than 36"
That should have been shown as change in system Q in an impedance measurement and an elimination in any impedance wiggle up higher in frequency. I would estimate (again without knowing the exact enclosure dimension) that it's a vertical internal standing wave that doesn't form until ~225hz or so. Even then he'd have to do a double layer of 2" rockwool since the performance of the stuff starts to drop even with the higher density foam between 250 and 500Hz pretty significantly.
U are the most knowledgeable channel that I visit on utube....great vid.
It would be nice to see further investigation on the effects of cabinet bracing and constrained layer damping. And also a comparison with plain old industrial grey felt.
I have used carpet foam padding on my subwoofer boxes. And had great results by ear not by computer analysis.
I am a speaker guy myself, but I am also *extremely* poor money-wise, barely able to (usually) pay my rent on time each month, (NOT rn though, because of the current, Spring 2020 pandemic and no work), so I can ONLY afford to design speakers and subs and other stuff on *paper* and with a calculator, and I can only afford to work with cheap speakers and stuff I find in the thrift stores or used...
I really WISH I had all of that "high-tech" gear and measuring equipment that you have there! My GOD, the totally EPIC and *groundbreaking* speaker designs that I could develop, test and build with all of that computer and pro audio stuff is only *imaginable* to me, but I certainly would get my use out of all of that kind of stuff IF I had any access to it! WOW!... I really LOVE watching videos like this about sound and speakers and acoustics because that is MY "nerdy" passion too, you have NO idea!
I always enjoy your videos man! I just wish I knew you personally and lived in the same city as you, so I could visit and talk speakers and electronic stuff with you for hours on end!
Super looking forward to the DSP multi channel tutorial. I've been thinking about going digital for a while now.
That mineral wool is exactly the same stuff as what you can buy in the hardware store to insulate your house with.
@@HexiBase I'd wager a guess the difference would be negligable, and most likely not worth the price incurred by having some sort of acoustics stamp.
Anyhow, I was excited for this video but I wanted to learn about how different angles effect the frequency graph. I saw an audiophile video with someone touting "defractionless" speakers and I could not find much information surrounding that. Sure it's certainly bogus, but a rectangle prism I'd imagine is hardly near our best option. Please drop some knowledge if you can.
@@steeezyb you would be better off searching for "diffraction".
Yea man, Rockwool RW3 or RWA45 is standard mass produced insulation stuff. It is designed and rated for acoustic insulation as well as thermal.
In the USA a lot of recording studios prefer Owens Corning resin fiberglass panels www.owenscorning.com/insulation/products/type706andtype707seriesfiberglasinsulationboards , because they are less prone to shedding the horrid rockwool dust.
Check out tech ingredients video on diy acoustic panels and absorbing materials
Regular fiberglass pink is not much different from egg crate insulation. If you manage to find stuff labeled as "Quiet Zone" or some thing like that, it will be superior to regular pink. It is however quite a bit more expensive, usually about twice the price. And it is usually not as good as mineral wool, but is often somewhat cheaper as well. So you have some gradient of trade off vs performance. For my low power system I went with mineral wool after trying many other things. In my situation it was the only thing that worked to my satisfaction. And this is also keeping in mind the room is purpose built.
A hamster crawled through the bass reflex port of a friends subwoofer, and could not get out again.
So he lifted the woofer and shaked it to get the hamster out.
That did not work, so he had to dismantle it to get the hamster, which had been shaken around in rock wool. It died a few days later, and his daughters got sad.
As for the good sound absorption. I think this is due to rocks higher density, so the fibers resist moving with the sound waves. And there should also be optimal thicknesses of the fibers, matching air diffusion distances at different frequencies.
4:31 It would be awesome to see a plot of the light blue curve minus the yellow curve, or perhaps the absolute value of the difference, if the program you are using allows it.
I like the results shown in the video but I would have preferred a deeper look at what enclosure resonances actually are and where they stem from. You almost started to dig deep with the look at pressure response inside of an enclosure but just kinda left it hanging there. The thumbnail had me thinking you were going to talk about the effect (or lack there of) of adding 45 degree corners. Talking about bracing enclosure panels would fit nicely in a longer more in depth video about enclosure/panel resonances. The effect of a double baffle vs dowel vs I-beam style bracing would be fantastic. Keep up the great work!
Finally a side by side comparison! Thank you that was a great video!
I use polly-fill myself, I like it's affect better than foam. But I've never measured the before and after, you've definitely got me wondering about that wool stuff though! That's an impressive result for sure.
Can you please make a tutorial, of how to make correct time alignment messurements, and how to eq properly. there is'nt much info about that.
thanks from the netherlands
MOAR MINERAL WOOL!!!!!
That wool seems identical to what I have uncovered in older GM cars for road noise, and I always tore it out in favor of Dynamat!😆
Actually mild steel sheet with dynamat could work as a pretty effective membrane absorber if correctly designed. Possibly with some holes in it, and an airspace behind it.
Your videos are really good learning material! thanks for doing this!
Please do a video about room modes and the compensation with 2 subs.
The great thing about the interesting hobby speaker building is that each detail of it can be a whole science on its own. You can produce different results depending not only on the type of material you use but also on how the material is distributed inside the box. And iif you start to combine different stuffing materials, try several styles of bracing and use separate absorber chambers inside you can experiment for years!
hope to see lots of videos coming up from you Pete these days, lets have some positive stuff coming up out of this quarentine disaster....we need more content, in a couple of weeks ill be running out of good movies and series...lol
Have you ever looked into mass-loading (sand-filled walls, inner walls lined with dynamat between the cabinet & rockwool), or constrained layer damping & its affects on cabinet construction/resonance?
The mineral wool look like it's impressive stuff. A bit like the work you do!
@@HexiBase Your welcome.......I'm still waiting patiently for that transmission line home theatre sub, man!
I'd recommend using a cheap machete from harbor freight, just make sure to keep it sharp. It'll slice through the stuff from orange or blue cleanly and with minimum effort. I've been stuffing the walls of my house with the stuff mostly from blue, it's slightly thicker and denser, but I never considered using it in a speaker box. I have a project coming that it may be useful in. Thanks for the tip!
Do you subtract the air space taken up by the egg crate foam or mineral wool from your boxes air space?
In this case it's infinite baffle so the volume is already correct
how much does using mineral wool change the air volume in the encloser, and how much of the graph change is due to the smaller air volume now?
I would love to see a video or series of video on room correction and bass management using miniDSP and mic and rew.
Not able to find any online wonder how people missed this is the core. I won’t mind to pay for such a content
Excellent work as always. Thanks for putting that into a visual package!
Your videos have gotten so good in recent history! Great animations, graphics, and presentation style.
Outstanding
Working on 2 sealed 12” right now
You should try the fxtreme DB450 DSP amp! it is wayy better then any other amp boards, and it has literally everything already build in, bluetooth, DSP, 4 channels (2 channels bridged) and even a freakin step up booster! so basically a AIO lol.... i already bought it a few weeks ago and it really is the best amp money can buy
Interesting! I was wondering what your thoughts were on poly-fil stuff! More like when to use vs not to use situations.
I also would have liked to known his thoughts on that since he has not answered you back
Except for he answered it down below in somebody else's comments and I just found
The difficulty of mapping semi-conductive elements within an enclosure is the reason why the aperiodic enclosure design was omitted from the original thiele & small papers on parametric modelling of enclosures.
In all honesty that rockwool isn't thick enough to really influence subwoofer frequencies, and if you look at many of the commercial sealed cabinet designs from pro audio, it is typical to fully-fill the cabinet with polyester wadding in order to achieve a relevant level of resonance damping.
I would expect that a box entirely filled with rockwool would be quite successful in reducing resonances, but might be difficult to model.
Have a look at this BBC research paper on the subject of wideband rockwool absorbers for reference: www.bbc.co.uk/rd/publications/rdreport_1992_11
Also for reference note that low frequency absorption is not generally achieved using rockwool panels, but instead by using perforated membranes: www.bbc.co.uk/rd/publications/rdreport_1971_15
There is a lot to be said for solving the problems of speaker cabinets using the same acoustics toolbox and materials palette as is used for an architectural scale space, although the general assumption has been that speaker cabinets and smaller rooms do not have the required volumes required for the absorption of low frequencies using foam/mineral wool.
I agree with you, the wavelenght of low frequency are to long to trying to damping it with any absorbers materials, the most important in cabinet for low frequency driver is eigenmodes of the cabinet himself. Some commercial brands just put absorbers in there subwoofer to make it look great when customers look inside, but most of the time it's totaly pointless.
It need several meters of foam absorber to start damping 50Hz who has 6.86 meters wavelenght. Sorry for my English :D
Just a thought: Maybe the mineral wool dont absorved this 50Hz resonance, it slow down the air in the cabinet at a specific location and calm down a cabinet eigenmode around 50Hz. if it really absorved the 50Hz resonance so why it didnt absorved the 80Hz resonance and all the little dips after 100Hz which got a shorter wavelenght, in theory it's easyer to absorve a shorter wavelenght. just a thought btw.
@@Jean-Triphase well, suffice to say that almost all decent quality PA cabinets have fairly thick lagging inside them - usually wool felt of some sort. The dynamics of the system and how it pressurises and depressurises - and also how wave fronts propagate within the cabinet - the general assumption is that supplying enough dampening material at the boundary thus removing the ability of the cabinet's internal resonances to result from unwanted reflections and standing waves / comb filtering is appropriate. For a subwoofer the effects are going to be negligible, whereas building a 4ft deep box/tube entirely filled with rockwool very likely would produce a totally different but hard to model enclosure. This would allow both the exploration of the more detailed sorts of analysis of exactly what rockwool does, and also would very likely produce a resonance-free and back-wave free enclosure which might outperform a sealed cabinet in terms of frequency response if not efficiency.
One question is... what is the speed of sound in rockwool?
Yes PA Speaker or even Hifi, Pro monitoring for the absorve >500Hz. Braces is used for control 500Hz. I still maintains Wool is nearly pointless for absorbing frequency resonance inside a subwoofer cabinet.
@@Jean-Triphase well, regarding frequencies, depends on the size of the box, really.
The problem is that if you over-fill a cabinet, you start changing the speed of sound. That is the "secret sauce" and patented method in PMC's transmission lines.
foam, rockwool or any other similar stuff dont´t have any important effect on bass region, under 200Hz fibers do not absorb or dissipate nothing. When you need to absorb or dissipate energy in that frequency range, vibrating panels are used in conjunction with some absorption (membrane resonator), or bass traps that depend on the dimensions of the wavelength (1/4 lambda) or helmholtz resonators.
Foam or other similar stuff inside box absorb only the highest resonance internal modes. The effective response on bass depends on box dimensions (due to refraction, 100-400hz) or on main modes of the room.
Below 100Hz, in a normal room (without very deep bass traps, or any treatment in that region), the frecuency response is heavily influenced by the resonant modes of the room. And the equalization does not have much effect, because once these resonance modes are activated in the room, they are "hung", ringing for a while once the sound source stops emitting. Waterfall plots are very helpful to see what happens in the room on extreme bass
They sell that same insulation at my Home Depot. And a regular serrated bread knife cuts if perfectly.
I am curious about how denim house insulation would compare, or the very expensive stuff that GR-Research sells. Love the videos.
Total überteuert. Wie Bondum800 in Deutschland
Do you have any videos on box geometry, as in what the optimal solid would be? Such as a cube vs. a sphere, maybe even comparisons with some other solids such as the other platonics, or the more easier to construct archimedian and catalan solids; I'm also somewhat curious about how a toroidal enclosure would theoretically work. I know this would only really be demonstrated with air velocity/pressure simulations, as there's no real way to make a truly spherical enclosure easily, and finding a way to glue together a large solid that isn't a cube could be fairly difficult. I'm just more curious as to how deviation from 90 degree corners would affect output; say, would a tetrahedron be better or worse, or would an octahedron be better or worse, then so on until we get to something that's too difficult to manufacture, like high face count solids and spheres.
If sound quality and subwoofers alone would get human kind to Mars... This guy would have made a team of scientists and would have already came back.
There are mineral wool knives for cutting that stuff that are cheaper than the electric and work great
imma just slap old clothes and towels in my sub. works fine.
If you put a mesh separator in the middle. Then put an hinged lid on the top. Make sure to install a air tight gasket, along with a latch strong enough to keep it sealed. You then have a (can’t combine the words together to make sense) laundry basket/subwoofer.
An SQ competitor once told me similar results were had by using recycled denim carpet underlayment. I tried it on his suggestion. Seemed to work really well at a fraction of the cost of the mineral wool.
Great video as always, its our first day on lock down so really appreciate the positive distraction!
Pete Bravo excellent good video topic of choice for discussion. You are going to educate a lot of people with this video
Love the detail you go into and the pace. Thanks for sharing.
What simulation software did you use in the video?
thanks for my series tune dual bass reflex enclosure. From AZ
so then what about 90 degree angles mentioned in thumbnail
HexiBase hits me in the gut, Love your videos!!!
Glass wool has been used in older west German studio monitors with lots of success. I've used rockwool in old Dali towers myself and it not only corrected peaks and valleys but lowered the bottom end a bit, too. Though that's a reflex box.
Thank you
Please do a video on the DSP devices by Audio Dynamics.
Great video! At 2.37 you use a spray gun. Is it glue to mount the boards in the cabinet or a varnish that will bind the stone fibers in the Rockwool board? Dust can damage the speaker coil. Know that Rockwool has boards that have a cloth on one side to stop the dust in the board. Take a look at their acoustic range, next time. Rockfon is the brand. There, the boards are covered on one side of canvas or acoustic paint.
amazing videography
At time approx 1:25 you show cabinet internal pressure simulations-what software is being used here? Assume more "price friendly" than Comsol?.... Cheers.
Are you calculating the sectional density and volume of the dampening material for wave reverb delay /phase delay to impact resonance vs just using a more efficient enclosure ?
Yes, it absolutely changed the volume of the enclosure a fair amount.
@HexiBase great job bro! & my box is like the 74 litter but it is powered and has a rectangular vent that I don't know if I should close or leave open? I just watche movies if that helps. lol
So you’re telling me that filling up that space with all that wool does not affect the volume of the box?
I use a product that is a dense CCF. It is about 3/16-1/4" thick. Bought a 100' x 4' roll at a yard sale, there isn't a branding on it.
I haven't modelled its response, but it did noticable smooth out the perceived sound.
Power handling increased, proportionate to the number of surfaces inside the enclosure (18mm Lauan plywood) that were treated with that CCF.
The sub acts as if it is mass loaded. Very intriguing.
Thanks for the visual representation of + and - pressures. I look forward to your next video.
Although not as easy as foam or insulation have you done any testing with angled corner bracing to kill the corner waves?
This video is very helpfull, bro. Thanks for that
Have you ever completely filled the box inside with poly fill or other absorbing/ damping material? What was the results? ..or what your recomendactions about this? Thank you!
Is the enclosure made with mdf if so I used to install car audio for 15 years. Mdf is pourers meaning it’s compressed wood that air can still penetrate the material. When I design a box I fibre glass the inside and then paint the inside with bitchinum paint which builders use on the roof. Then apply the sound proof
. Amazing results.
I’ll send you pictures of my installation which I’m doing to my van
Can you make a video on modeling enclosures for a room
Put activated carbon in the bottom and test again. I bet you would see an even bigger difference.
I always enjoy your content. Luckily most of the car audio enclosures I built (1980's to current, LOL)had at least 1 angled back wall or speaker face. I did experiment with different methods to reduce standing back waves back then.
I had a enclosure design I was gifted in the early 90's that I can only remember a few details about. I'd like to see if you can help me identify what it was. Keep the videos coming.
So when you add the dense mineral wool the box volume is reduced. This test compared to the volume of the empty box would not be the same test correct?
i thought that filling a sealed box was the way to go, there are special sealed box damping material for that.
Out of curiosity, what would the response be on an enclosure like this if you added a small port to it with the mineral wool? Also how would a rounded enclosure effect the sound and response of the sub? Meaning the inside of the enclosure being egg shaped.
That mineral wool reminds me of the USD Audio AP mats form back in the day.
Hello! Tell more about modeling response of speaker and enclosure PLEASE! How dou you predict it?? What software do you use?
Hey, great video. How did you simulate the air movement?
I'd like to know as well!!
@@HexiBase I've seen other videos of yours with calculated frequency responses for all types of enclosures. I use WinISD and only have a few options for enclosures. How would you calculate more advanced responses?
Isn't a sphere the most 'ideal' shape for an enclosure? Could be done easily in a 3d printed design.
I love your work - very thorough and most helpful
I noticed there is also a "sound dampening" mineral wool out for between walls. Might be worth the extra cost.
Sound insulation is not necessarily a good sound absorber. Concrete is an example of the former only. In a speaker box you want something soft enough to deform at the relevant frequencies and SPL to re-release the energy slowly. I would guess that rockwool suffers the same problem as foam. Too firm. With polyester the apparent volume of the box can even be increased.
@@michaelpiotrowicz6100 I think you would do well to do some reading on the speculation about how exactly rockwool is absorbing sound. It is primarily gas flow impedance (also termed air flow resistivity), but also relies on qualities such as tortuosity and porosity (coupled flow nightmare).
It is not a simple matter. Rockwool works, of that much we are sure, and most of its effects can be modelled simply by its ability to impede gas flow.
Here is some surface to start scratching:
resource.isvr.soton.ac.uk/staff/pubs/pubs47.htm the paper by fahy and Thomson on the coupling of perforated/porous solid surfaces to air is worth a read.
@@weareallbeingwatched4602 thanks for that. Some experimental literature that you might find interesting, and which is consistent with my experience, is available to read here sound-au.com/articles/boxstuff.htm
What about the common poly fill?
If planning for the wool, does it eat up some air space? In other words, build a little bit bigger enclosure to get your net volume after the wool?
I usually do minimum 1" walls with overkill bracing. Then loosely fill with poly.
Seems like a very expensive way to smooth out the response. You did not state how much reduction/improvement you've got (in terms of db), and whether the wool affected efficiency, And whether you've actually heard the difference, especially with music. Personally, I'd first modify the internal geometry by getting rid of the 90° corners and filling the box with a cheaper alternative.
What about changing the geometry of the box?
Was it worth the time and money to switch to the Mineral Wool? To me there was little effect between the different insulation types. It may change the graph some but can you actually hear the changes?
Can you do a dedicated video on the bass reflex band pass box, the one where it ports into another chamber I would really like to build one but can’t find any more information on it besides the uncommon box video you made
How can the mineral wool in that small box affect 18Hz. Something is wrong. Think you are using more smoothing on that last curve.
Would adding 45s in the corners help?
Love your video. Question for you HexiBass - with sealed enclosures, would filling it airspace with hexafluoride gas help it sound deeper?
What if you change the internal shape? If you stick to the same size cabinet, what happens if there are no parallell walls? If you curve the rear wall, and the side wall? Or any other shape you might fancy that might help sound wave reflection? For years I've been having this in the back of my head without finding the time to test it out, and also I don't have any test equipment or skills how to use such tools, so I would have to rely on my ears and only them, and I am not sure they are good enough to hear any difference. Have you ever tested this out in real life?
@Hexibase just wondering if you have ever dabbled with some Isometric Pressure Speaker drivers? Vifa makes some good ones. I have the Vifa Helsinki and its one of the best sounding Bluetooth speakers i have ever listened to. I bet you you could create a kick ass Isometric Pressure Speaker set up with your vast sound knowledge.
Still don't quite get why too much sound processing sounds unnatural? Maybe you could do a video on it?
i think it mostly refers to trying to fix the natural destructive nodes through dsp instead of actually fixing the room/speaker positions/speaker cabs. if the problem is severe, you're just going to be adding a lot of distortion because the amp will clip first at those huge spikes, and the speaker will distort since it is still working harder, but it will be naturally muted due to the destructive node cancellations.
i personally have this problem, (at around 120hz for me) and my audio suffers because of it, mainly classical music which has huge dynamic range (and imo, unnecessary). i'm not a perfectionist, and because it works well enough as it is, i haven't bothered fixing it.
I ordered a mini dsp c6×12 for my car but I now need to buy a Windows 10 laptop to be able to use it lol! Look forward to any videos on using the minidsp products and tuning
What effects do sound deadening with the likes of dynomat make?
Always a 👍.
Could you show us what software do you use for all that measuring, calculating and predicting?
@@HexiBase Specifically, what was the FEA tool you used to model the interior wave propagation?
How much the volume the insulations occupies inside the box? would be interesting to test the same real volume in an enclosure bigger enough to compensate the 2in thinckness of the rockwool
Can I do a push pull isobaric with a front facing subwoofer and a down firing subwoofer firing into the enclosure from the top at a 90 degree angle from front subwoofer?
Pretty cool. I could definitely hear the difference through my woofer.
excellent quality, both from informative and production point of view.
Hey, your videos are already quite advanced. Are there any good resources you would recommend if one wants to start with speaker building?
What software do you use to simulate the enclosures.
Great work 👍
Hi there, I just build a subwoofer with a Skar audio enclosure and a 10" Electrovoice Subwoofer driver, it produces excessive vibration all over the house, so I tried to isolate it by placing the subwoofer over a piece of foam and it worked 75%, do you have an idea on how can I can reduce more of the vibration? Thanks in advance...
What kind of software models the pressure waves like that inside the box?