NOTE: This is to clear up some confusion over what I meant about bracing and damping: Speaker building was always bracing and damping. But at some point the idea started that bracing alone was better, just using a lot more of it. Guys were still doing the traditional bracing and damping (like me), but you also started seeing these bracing only builds happening. The idea was to drive up the panel resonance high enough so that it wouldn't be excited and therefore wouldn't be a problem I'm speaking 100% from a DIY standpoint, not from what the major manufacturers were doing. Will making the entire box from the same material make a difference? Possibly, but I did what I could to take the rest of the box out of the measurement. For example the box was clamped down to my very heavy and stable workbench to keep it as stationary as possible, and help restrict the measurement to the panel itself. Yes the other panels were still vibrating and in turn that can affect the panel being tested, but it's the same for each of the different panels. Each panel was exactly the same size - 8-1/2" x 12" with the screw holes in exactly the same places. Why 30Hz to 2000Hz? I did some "warmup" testing prior to the measurements I made to determine the best range that shows the most relevant data. 30Hz because the speaker I used doesn't have significant output below 30Hz. I used my ACH-01 accelerometer connected to REW to run the measurements. I made a special preamp for that accelerometer in this video: ruclips.net/video/o1Fctgs8CcQ/видео.html My conclusions are that the material used is not a significant factor in how the speaker will sound. As long as what you are working with is of reasonable quality, you should not be able to hear the difference. You may be able to imagine you hear the difference, though, and the human psyche is a powerful thing to overcome. If you believe MDF sounds dull and sluggish, and Baltic birch plywood sounds lively and fast, then it'll be very difficult to get past that and you should use the one you think will sound best. As for bracing vs damping, I think both are valid. Use bracing to reduce panel size so that the damping will be more effective. The rationale of those that prefer bracing alone is that the damping "smears" the response. Much like above, it'll be hard to get past this idea if it's what you believe, so best to go with what you think is better way.
While listening to you explain damping vs. bracing on the video, I think we understand damping differently, and I was curious if you mis-spoke, or I mis-understood you. There aren't very many times where I think you are wrong, or disagree with you, so I thought it was interesting. From my reading on the subject in the past, the stuffing, or damping material is to slow down the sound waves to enable a smaller than the math shows box to be used. In a sealed enclosure this is done by stuffing the box, and in a ported enclosure you more so line the box with stuffing so as not to miss up the air flow from the box to the port. Niether of these things have anything to do with panel damping as far as I undertand. Now if you were too put some type of butyl paper, or the like on the panels, that is meant to damp the panel. But those things would actually drive the resonant frequency down (edit: of the panel) due to adding weight. The bacing on the other hand would drive (edit: the panel resonant frequency) it up, I agree, due to making the vibrating panel smaller. This was a pretty sweet test, that changed my mind alot about MDF being the superior box material for sound deadening. Prior, I had only read opinions on the subject, but seeing a straight up test, kind of changes things. I don't know how well these speaker videos do for you but I for one enjoy them, and this one especially was interesting. You keep making em' and I'll keep watching em'.
@John Heisz - Speakers and Audio Projects Nice test, John! *EDIT: I just watched your speaker enclosure "Stuffing Comparison" video so disregard some of my info/points below* But, I would not have clamped the enclosure down, at least I would not have clamped to the TOP of the enclosure, as that will SIGNIFICANTLY damp and reduce the top panel vibrations and change the overall resonant frequency. Those clamps will absorb A LOT of the energy and "normalize" the differences between the various panel types. Instead, I would have built the enclosure with a base panel (the bottom panel that's sitting on your benchtop) with ends that extend past the vertical side panels an inch or so on each side to use as your clamping points or "wings" at the base. This will still "damp" the enclosure overall and change its resonant frequency, but would not have affected the resonance of the top panel nearly as much as the top clamping points did! And to be fair, in the real world none of us "clamp" our bookshelf or tower speakers or subwoofer enclosures to the floor or any other supporting surface, so there's that. ;-) I also wish you had taken nearfield measurments of the actual Acoustic Response of the Speaker itself in REW using the different panels with & w/o the internal acoustic damping material using your miniDSP UMIK-1. That would easily show if any of the changes were actually audible or changed the acoustic response of the driver's output. ;-) Obviously, the overall size of the enclosure/cabinet will drastically affect the frequencies and amplitude response of the various resonances significantly. And with each unique enclosure, you must also take into account the potential internal resonances due to standing waves that will occur due to the specific HxWxD dimensions of the enclosure. IMO&E, using good internal bracing and a SOLID, DENSE Mounting Baffle for the drivers is important. The best performing enclosure I have built in terms of being resonance-free were from 1" thick HDPE or UHMW plastic panels. Obviously quite expensive and as heavy as an elephant, though! But this material is nice because it can still be cut, worked, & shaped easily using your standard woodworking tools...tablesaw, router, drill, sander, etc. You must use fasteners and not adhesive to build the enclosure, but you can use thread taps and machine screws to construct and secure the enclosure panels and make them infinitely removable. I use a 1" wide by 1/32" thick foam self-adhesive gasketing tape between each panel's adjacent connection surface. Of.course, all of your cuts must be perfectly square and smooth in order to seal the enclosure. Finishing this type of cabinet and making it aesthetically pleasing is the tough part. :-( IME, I have found natural wool fiber to generally work best as internal acoustic damping/stuffing material. Danny at GR-Research also sells a self adhesive backed sheet foam damping product called "No-Res" which I have found to work well to line the cabinet walls themselves. YMMV The natural wool, polyfill, fiberglass, or mineral wool batting or "loose fill" helps reduce both the mid-to-high frequency panel resonances, as well as raising the QTC of the enclosure (making it effectively up to ~20% larger overall) by converting vibrational energy (sound waves) into low level heat. Google Search, "Make A Small Box Act Like A Larger One With Polyester Fiberfill By TOM NOUSAINE". As you alluded to, I will often use a Constrained Layer Damping sheet material ("CLD" tiles/mat/sheet) such as Dynamat Extreme, ResoNix CLD Tiles (best performance), or Stinger's Road Kill Ultimate (which adds a foam isolation/decoupling layer) to the inner panels of the enclosure to dampen resonances and reduce the resonant frequency peaks. CLD "Deadener" or "sound deadening mat" is made using a butyl rubber-based compound (usually with mica and/or talc added) that is topped with a thickish aluminum foil type "constraining layer" and has a self-adhesive-lined backing on the butyl side. This combination of materials works extremely well to dampen panel resonances. To save on materials and costs, attaching a smaller piece of the CLD sheet or "tile" in the middle or center of a resonating panel works nearly as well as lining the entire panel with the CLD sheet. I have also used "Green Glue" acoustic damping adhesive to attach and line the interior panels of enclosures with Alphasorb Wood Fiber Acoustic Panels which works incredibly well, though you have to design and build the enclosure larger to offset the reduced internal enclosure volume. To learn more about the potential audibility of enclosure/cabinet resonances, go to the *Erin's Audio Corner* RUclips channel and watch BOTH of Erin's objective measurements (Klippel Analyzer/NFS) & subjective listening reviews of the *Klipsch Heresy IV* loudspeakers. Many of his other speaker reviews cover this topic as well. Basically, a.simple impedance sweep measurement using an inexpensive DATS V3 unit will show any resonances as "blips" or "bumps" in the impedance curve or plot, and they will correspond to anomalies in the on- & off-axis frequency response. Keep up the great work!
You've only measured 1 side of a 6 sided enclosure. What you've measured is the characteristics of that one side. When coupled with the face, side, bottom and top, they'll react differently unless you've produced a perfect cube. Another school of thought in speaker building is many designers WANT the face (I forget the technical term for it, the panel the speakers are mounted to) to resonate and produce sound on their own. This panel can be tuned to augment the actual speakers and produce a desired sound. Also: who uses 1/2" material to build a speaker? If you're building tiny bookshelf speakers I can understand it but for any serious main speaker? 3/4" is the norm, 5/8" at the bare minimum. If you're using an 8" woofer you MUST use 3/4" due to the sound energy it will produce. To be accurate, you really should build the entire enclosure out of the same material. What you've done is like testing the water quality of a lake by testing a sample at one end, near the shore where your cottage drain pipe is located. Go to the source of the water, a spring, and the water quality will be different.
Your findings are very accurate. Bracing helps more than dampening, but both are useful and necessary. Dampening will reduce the amount of energy reflected back into the cone. Bracing raises the resonant frequency of the panels.
I'm enjoying this whole series John. We used to spend hours in the warehouse A/B comparing all kinds of things. One of the breakthrough days was when we got a crossover that could time align the drivers in a horn loaded array... The pressure level differences were quite notable.
About 40 years ago a friend of mine had his brother build him a pair of speakers. The cabinets were plywood and the drivers were from Radio Shack. They stood about 3 feet tall, 2 feet wide and a foot deep. To this day they are the best sounding speakers I've ever heard. I need to ask him if he still has them. My guess, the drivers have turned to dust by now, but it would be a cool re-build with modern drivers.
Probably already commented on, but my guess is MDF is used mostly because it's always flat and takes less work to finish for painting/wrapping. Great video!
Excellent and informative!!! I was a master installer at a high end shop for 9 years. Our material of choice was Trupan cabinet-grade MDF. Generally the enclosure was glued and screwed, then ALL inside surfaces were painted with latex paint to prevent 'breathing'. For aesthetics all non-upholstered areas were painted as well. The material would leave talc-like sawdust and just EAT router bits and bearings if not fed or cut slowly.
I am thankful for this ...I was looking to repair my old Dahlquist DQ20 speakers and i didn't know what material to use ,.My beloved speakers got water damage and i want to revive them .So your effort has been what i needed to know ..
I always put stuffing in the speaker box to stop sound waves bouncing of the clean walls and repeating back onto themselves and the driver. Remember when adding bracing you need to increase the volume of the cabinet because the brace takes a lot of volume up. I made a set of speakers years ago that had angled sides, multiple braces, stuffing, one coat of paint on rubber membrane them a second coat of rubber with sawdust added. Cabinets made from 18mm MDF. Still listening to them today. Good work on the experiments, it's the only way to really find out!
OUTSTANDING VIDEO!! Wonderful to see some empirical testing on enclosure material resonance. You confirmed a number of longtime observations I've made myself. Personally I've found that a combination of bracing (of different types used in the same box) and the use of laminated panels is very effective at eliminating resonances. If you glue a thin (1/4 - 3/8) panel of (quality) MDF to a Baltic birch plywood panel, the result is amazingly stable. You have to use a lot of glue, and make sure it is uniformly clamped together, but it's worth the effort. Many of the high-end speaker manufacturers utilize composite layers of different materials to absorb resonance. The key is using materials with different *densities*. When the energy hits material A it bends at angle X, for example. As it passes from material A to material B (of a different density), it bends again at angle Y and so on... Each change in direction absorbs energy. I'm an instant fan of your work, thank you!
This was great and hopefully many will also learn about measurement, interpretation and practical application, (as opposed to folks going weird with the end-grain video).
Ages ok (mid-80s, I guess), a friend of mine had an old pair of speakers, something from the 70s, pretty standard stuff, just like the rest of the equipment. The drivers had paper cones with stiff suspension, the soft "rubber" wasn´t really standard at the time those were made. Those speakers were ok, but down low their resonance made them sound quite undefined. After a little thinking about it, we removed the drivers, measured the inside dimensions and cut a few pieces of wood, about a 16th oversize, wedged them between the centers of the panels and remounted the drivers. The low bass got much better, it sounded much more responsive and defined. It still was far from comparable with higher-end contemporary stuff, let alone modern equipment, but it was definitely an improvement.
back when i studied sound engineering and was into speaker building, my conclusion was the material is not as important as the construction. meaning adding bracing reduced resonance
one though i had on bracing was to not divide areas in half but use perhaps 1/3 etc to not get two areas that have the same resonance since this in my experience makes the resonance multiply by each surface with same area. also overkill is always good :P ply or mdf with 1/3 bracing, damping with foam and filling with poly can be combined for the best :) really enjoying these vids!
One thing that these measurement highlight is how small overall the differences actually are. Like having a microscope and seeing things at 100X. For each of these sweeps, I couldn't hear any difference at all. It's like every other technical subject, where these minor differences often get magnified and given more importance than they deserve.
Great video! Good to have actual measurements to see the difference so I can use veneer plywood instead of mdf. One thing to try is using stick on vibration damping material used in vans to see how well it would work with wood.
@@llee4225 I don't see why it wouldn't work. If it can help reduce rattles or in some cases rid of rattles and squeaks all together in some older vehicles you'd think it would work inside a speaker box also. I've actually been pondering on replacing the old original damping material in my vintage Pioneer CS-53's with some DynaMat or a quality equivalent to see what would happen. :)
@@llee4225 I think comparing how well it works on large thin steel panels, compared to a thick piece of wood panel, doesn't work to well. I'm guessing if he did a comparison between this test result and then added dynamat or the like to each panel and did the same tests there wouldn't be much difference. I think the wood is WAY more damped than the van panels to begin with to a point where it would be a pointless expenditure to purchase the dynamat. Agreed that it does wonders in a van though.
thanks for posting some actual testing verified with results. I like your questioning attitude. As for the resonance issues if you look at the speakers often used in sound reinforcement in live performance and DJs they are mostly molded plastic and iff the equipment is set up correctly for the room some of them sound pretty dam good . Like any musical instrument like all the horns wood winds and brass it is primarily the size and shape of the cavity not the silver and brass that make the difference between OK and great sound.
This is a great project with good discussion. I would suggest that you could test the speaker cabinet in a free-free condition by supporting it on some soft foam. This would also eliminate the boundary condition created from clamping the wood panel through to the bench - this will likely affect the panel resonance and modes.
In a quiet well designed listening room with people willing to concentrate on critical listening, they will hear slight differences I think. My friend and I build speakers and for a test we both used the same 5" woofer and 1" tweeter and built 4 different boxes with the same air volume for bookshelf speakers. They all sounded different but the best one was built from laminating 3/4" birch ply and 1/2" MDF together for a 1.25" thick cabinet wall. The idea on that one was making a traditional rectangular speaker but with complete overkill for cabinet rigidity and using plywood and MDF with a layer of contact cement would provide some extra damping for the cabinet wall it self. Another one was made from laminating many sheets of 1/8" MDF into an oval cabinet. Those two examples were the most different in sound. The oval one was ringing as if some bass and mid bass frequencies were blending together, The 1.25" thick one seemed much more refined with no noticeable ringing and a tone/frequency sounded like it was more true to the source track. No braces were used in those but I've added bracing to larger speakers before and that does seem to work better in general.
Thanks for documenting the experience, some thoughts come to mind. A loudspeaker enclosure is a 3D structure which is most often heard also mounted on a stand, the resonance modes of such a structure are not necessarily the same as the resonance modes of a single panel firmly attached to a heavy woodworker's workbench. Plate theory offers good ways to predict the modes of a rectangular panel made of isotropic material, but the analysis of the "3D" modes of the entire enclosure on a support is much more difficult to predict. Add to this that opposing panels could resonate additively and radiate sound into the room, but could also have modes in which they move identically, hence subtractively, and therefore do not radiate sound at a distance. I fear that it will be necessary to build an enclosure entirely and measure the accelerations of the opposing panels to be able to accurately compare the influence of the materials used on the distant sound field. Would be super interesting to also add other type like HDF, Bamboo ply, CLD with polymer, ...
I remember that sound. I worked at Allison Acoustics in the '80's. Started out doing production. Worked my way up to testing. We tested components and finished speakers. Our cabinets were MDF with a fake veneer on the outside. Inside we placed a small amount of fiberglass.Never used isolation rings on the speaker basket or bracing. Dr. Roy had the cabinets made to his specs. Never tested cabinets. Interesting show.
Cool vid man. Thx for taking the time to build the experiment and edit down to such a pleasurable video. Man of many talents. I think I say that every time I watch something you put out. Lol
I used 1.5" solid walnut butcher block for the baffle and a layer of 1/2" mdf bonded to 1/2" birch ply for the rest. Sounds great. I think the thick solid front contributed the most.
Looking at the location of the bracing, it seems pretty much in the middle of the box - so any panel resonances would be be at the same frequency above and below the brace, giving a single peak which is the sum of both sections. What I might try is offsetting the brace so it’s not symmetrical - I’d have to do the maths but my guess would be that the golden ratio might offer the best performance, giving two peaks at different frequencies which don’t sum to a higher peak like they would for a symmetrically placed brace.
Thank you for all the great work, investments in time, energy, funds and skillset required, to accommodate the information you are presenting here! Much appreciated.
Bracing panels forces us to think about the vibrations of the panel itself rather than the resonance modes of the internal air volume in the box. If we put reinforcements in the main resonance modal lines of the panels (1/2; 1/4, etc) , creating symmetrical divisions, we will have 2 or more identical zones resonating at the same frequency (+3dB reinforcement). That's why it's recommended that the reinforcements be located in asymmetric divisions of the panel in question. You also have to think about the size of the resulting sections with the division. If a 12" panel is split at the center, we will have 2 resonant 6" sections; the ideal is to have zones no larger than 4 " (this pushes resonances much higher than 1kHz, which eventually makes their absorption easier by passive means (foam, textile fibers, etc.) Several studies show that the vibrations of the panels are not perceived if they are 30dB below the main radiation (woofer), in the bass region (below +-300hz), the teorical "limit" is a little less (correlated with sensitive hearing curves) (the BBC did important research in the 70-80s for the development of its monitors, there are excellents papers on the web about the topic)
I build speakers too and the crossovers. I use the 20mm pine ply for my speakers and I brace them with thin dowel by glueing the ends to the box panels across the speakers inside (several of them front to back and from side to side). I did it to save internal volume but maybe it's better than normal bracing, going by your results. Interesting that it makes such a measurable difference. Great work dude. Cheers Big Ears!
There was a thick ceramic paint that worked well back in the mid to late 80s. Then there is the dampening material used in cars. There is something called no res that is pretty popular now. As far as bracing goes, it works well also, but it works better if it is rounded over on any openings and where it isn’t attached as this tends to not allow resonances aggravated by the right angled surfaces. Opinions vary on this but my research backs up the rounded over bracing as opposed to that which isn’t rounded over. The materials used were mdf so things may vary with plywood. Baltic birch is very good for cabinets, but not so much for speaker enclosures. MDF is more dense and has better damping characteristics when treated with surface coatings or other dampening material. Most manufacturers don’t bother with any dampening as this adds to cost. Failure to use any dampening causes resonance issues and DIYers and Modders have been doing this for decades. It isn’t a mystery.
My initial guess would have been that particle board would be the worst, with OSB and various plywoods in the middle and MDF the best, so this seems to confirm most of that. I also remember some inexpensive speakers from the 1970s with dense Styrofoam enclosures that sounded much better that I'd have expected: not much mass, but maybe a lot of damping; a test on that would be interesting.
Thank you. I just build a box using 3/4" MDF, and I hate using it because it splits so easy with screws, even drilling a pilot hole, so I'm going to go buy 3/4 oak and try again.
Solid experiment. I am in the process of designing and building some sealed 15" subs. my plan is to use 3/4" BB and laminate a 1/4" MDF to the outside.. My thinking is that the BB is lighter than MDF so the subs won't be as heavy as using all MDF, but the MDF outer layer will make the veneer application easier.
Very interesting, John! I’m guessing the pine ply had the lower ringing due to the varying thickness of veneers, which make each layer less sympathetic to adjacent layers. I like to use two layers of granite, one being 3/4” and the other being 5/8”, laminated with a layer of 1/4” lead sheet. Let the tone wood debate begin😁 Thanks again for taking the time to test and share. Awesome!
About 40 years ago I built a set of 3 way tower speakers using 1/2" particle board with 1/4" Luan plywood laminated on the outside with for a nice looking wood finish. They are still going strong and the cabinets are still solid as a rock. The only inner bracing was a divider between the woofer and the midrange/tweeter section, to make the woofer section the right volume for the speaker that was used. I also put fiberglass insulation in the woofer section. I know particle board isn't really desirable for speaker cabinets, but even at high volumes the cabinets show no signs of vibration. I keep thinking that I'll rebuild them some day, but they've been such good little troopers.
Actually, there's nothing wrong with particle board. Hundreds of thousands of speakers were (and are) made from it. It's no better or worse than most other materials used to build speakers.
@IBuildIt A few years ago I renovated a pair of heads (MDF) with a 12" bass and a 1" tweeter with a 30cm horn - with a multiply (9-ply) beech wood exterior and a vented cabin. I dont like MDF, it's really cheap material and parts of the corners were broken off, I remade it. There was a big difference: clear, clean, no booming, that's why I decided to use the next cabin - RCF 18" ventilated (approx. 100 cm high, 70 x 70 cm), old: MDF, new: Mulitply - also there a big difference in the sound! I think because the MDF is softer, and the Multiply is much stiffer, minimal bending, so in my opinion there is less cushioning and more comes out of it! The best part is that the veneered surface makes it easy to get a brilliant finish, I use epoxy resin as glue, after 10 years no problem, no shrinkage, no leaks - and 3 coats of epoxy resin outside - the best result you can expect your work can achieve! My last project was an Electro Voice Eliminator - a 2 x 15" cab - a big deal, a lot of work - but in the end it rewards me doubly every time I play with it.
On my last speaker building project I used a knotty pine butcher block style project board from Lowe's. It's relatively inexpensive and beautiful with a bit of oil on it. There's no reason to fret about the material resonance if you address the resonance with bracing and damping materials. I lined the largest sections of panel with asphalt/rubbery type damping sheets, then used acoustic foam, then poly-fill. The result is a plenty-quiet cabinet and a beautiful knotty pine butcher block finish that required no nonsense to "finish." Just a rub down with some oil to give them a bit of rustic sheen.
Very interesting and very informative. I never liked mdf. It always seemed to not be stuff enough and therefore would require a lot more bracing. The effect of insulation on high frequencies was interesting. I would assume that it would be due to dimensions of the box creating "room" modes inside the box? Thank you. Very helpful.
It's a good ides to knock down those higher frequency "nodes" inside the box with damping materials, otherwise they will "ring" back through the cone and sometimes the port. Ideally speaking, we want to damp most of the energy coming off the back side of a driver down to nothing. Exception being low frequencies that we might be intentionally exciting a port or passive radiator or horn resonance with.
I’m pretty new at speaker building. I admit that I was surprised at how cheap most companies build speakers. Fairly expensive(for me) brand names tend to have cheap speakers, thin wood, light gauge CCA wires but made the cabinet look real nice and fancy. I ordered some actual Pioneer speakers, crossovers and build 1/2” thick sealed but ported cabinets and used copper wire for 1/8 what a nice pair of Pioneer cabinets would cost and they sound good. They’re not as pretty or expensive looking but genuinely sound better than the most expensive speakers Ive heard. Of course, the source has a lot to do with it but I am comparing these I build with a $800 pair of Fishers I own.
I like experiments like this. I believe the materials would have shown a greater difference if the accelerometer placement was on the speaker baffle itself. I realize that entails more work. Also, it would be enormously interesting if you had also tested a constrained layer damping material applied to the inside of the baffle such as Dynamat Xtreme. Also, there are manufacturers such as Magico who make cabinet enclosures out of billet aluminum and carbon fiber. They also apply damping materials such as No-Rez to the insides. Thanks!
Interesting. I've often wondered which material is best, and now I realize that I bumbled into the better one with MDF for the couple of pairs of speakers I have built. One thing that kept distracting me were those wooden wood clamps! Those are sweet. Now, I'm thinking about building some.
Another top tip is to laminate a panel of mdf to the inside face of baltic birch. This improves(reduces) time of resonance. Bracing works by lowering amplitude of resonance and shifting frequencies further up. Creating sub panels by multiple braces unequally spaced makes them effectively different sizes and splits frequency of resonance hence reduces amplitude of each specific frequency. Equal spacing creates lots of sub panels of similar frequency so doesn't reduce amplitude which becomes additive. Using 5 braces has a similar effect on resonance amplitude as doubling panel thickness so increasing nr of braces to more than 5 has no advantage over simply doubling panel thickness except that the larger the cab the lighter you can make it by upping nr of braces. Using visco elastic damping membrane on inside panel faces drops resonant frequency and lowers amplitude and time of resonance. There's loads you can do. As speaker size increases so mass increases and structural integrity becomes more important. This is where baltic bitch ply is superior as it has greater integrity through higher tendsile strength and greater resistance to shear as well as splitting compared to mdf.
I was considering this option as well, not only to tame Birch but maybe even something as radical as the grains from sweet gum that I have plenty of around here and would like to put to good use.
What a breath of fresh air! Now on to the most sacred of cows, the crossover. Can off the shelf crossovers of decent quality with properly matched drivers produce great sounding speakers? I think so, by using your ears in matching the drivers, like designers did in the old days, must have anyway.
I found this interesting. I use MDF instead of particle board, because I found MDF much easier to work with (much less chipping and much more reliable at holding screws).
Cheap plys and "particle board" would be more prone to chipping. I feel that plywood dust may be a little better for you than MDF dust ;p Not that either is great to breath
Interesting test. This pretty much confirms what I have heard by ear, in that there isn't an audible difference. I switched years ago to mostly baltic ply, for the reason that it's consistent thickness for the CNC, and that it's much harder than mdf, making a more durable end product. MDF dents and bends corners too easily. I also played with corian and phenolic, but again, the advantage wasn't sound, but rather a more stable material for finishing. If you want that Wilson finish you need to lay down a really thick layer of spray filler to encapsulate the joints, then wait months while the material settles down, swells, shrinks, and moves. Then and only then do you dare block it for primer. That said, take a close look at a wilson and even they have issues with their materials. You will plainly see the joints through the automotive finish.
Hi, I used to work for a 'name' top, top end hifi company and for hifi plywood is superb, plywood front and back with chipboard 'wrap' (sides, top & bottom) is great but MDF was absolutely awful! It howls and has huge upper-mid overtones.
I built a pair of small satellites and a pair of large bass boxes using 3/4" oak laminate plywood and they worked out quite well. My concerns with using plywood are twofold, first, that they don't lend themselves well to gluing on bracing on the inside of the panels, since the brace would be glued to the first layer of plywood only, and second, that over time the plys may begin to separate and rattle. For my latest boxes, I went back to MDF, since with the oak laminate material, I still had edges to cover, and with the MDF, I used oak laminate sheets to cover the entire surfaces of the front, top and sides. For internal damping, in the past I have glued carpet padding to the inside panels using carpenter's glue (called Powergrab) applied to several places on the padding. For the last project, I purchased water based roofing cement, and brushed it on both the inside panels and the carpet padding, applying quite a thick coat, and glued the padding to the panels, this provides both dampening of the panel and absorption-diffusion of sound waves inside the box.
INice video, so important to actually have tests and measurements. Interesting when you have ultra high end audio where concepts are brought to reality often. Totally having inert boxes has been achieved but some find the resulting sound a bit analytical guess many wants to hear favourable resonances to a point so now many speakers are designed specifically with resonances in mind maybe not as much as Harbeth boxes.
you are the only other person besides myself who seems to be aware that mood has a very real effect on how "tone" or anything really is perceived. Do only the Snake oil salesmen know this too? haha
Top secret tip: Glue together full sheets of 1/2" plywood + 1/4" MDF board with a synthetic rubber based adhesive. Rip and cut panels with regular tools just like using a thicker board. Use plywood outside for durability & MDF inside for good damping. This combination has, by far, the best properties for nearly eliminating cabinet resonance. Beats every other type of wood. The only thing better is rubber reinforced concrete. That stuff is impossibly heavy though!
@@IBuildIt So THATs what CLD means!! 😂 I'd only ever built speaker boxes the boring way (MDF, glue, screws) until I started investigating open baffle speakers. A few years ago I saw someone build a box with CLD panels (various other techniques employed as well, for mounting a measuring instrument I think), it was ultra-quiet inside. You could put a decent BT speaker inside and barely any sound got out 😂😂 So I went ahead and build a few open baffles, recalling whatever I could from the way this box was built. Admittedly, my understanding of acoustics & my woodworking skills are quite basic. But the resulting OB speakers were pretty spectacular to listen to. (They're downright ugly though, mostly made out of a combination of whatever wood I have on hand) Haven't seen too many folks use the technique on RUclips though, hence the "top secret" bit 😂
Finished my baltic birch tonewood speaker cabinet. Can't wait to set this bad boy directly on the top of my desk without an iso pad, backed right up against the wall as tightly as possible in my untreated sheetrock room with oak flooring. Just got a new subwoofer too. Points straight at the floor and is 2 inches away from it right from the manufacturer like they all do for some reason.
Tuned each face to 432hz with my chakra. Also everything I used is plugged straight into the wall instead of a power conditioner to get that organic sound.
I worked for over ten years in a plywood mill. There are several differences between pieces of plywood. They are not always solid. Especially in typical pine plywood. There can be areas of void in the individual layers. The more layers that you have, the less that these voids will matter.
This is why I made my guitar amp speaker box out of fir and pine. But.. if I'm not mistaken, it's not the actual sound of the box that it produces while resonating that's audible, it's what the shaking/resonating of the box does to the drivers as it shakes in and out of phase with them. That's what you end up hearing as artefacts in the sound. The volume would have to be ear bleeding in order to actually HEAR any sound from the enclosure itself.
Thanks a ton for these tests. Kept me from buying into marketing hype for hifi speakers with hdf vs mdf. For example polk legend L600 vs arendal 1723 tower (non-s). Very much appreciated.
The same experiment was conducted on another channel I’ll Fargo the channels name out of respect to your channel. In their conclusion they found out that plywood was superior than MDF material and that marine grade plywood which is very expensive was the best to use to make a speaker box. The only problem is the cost of the marine grade plywood to MDF. MDF was about half the cost the MGP would cost.
The thing to look at is stored energy in a water fall plot , that tells the real story of what the cabinet does to the sound , stored energy always shows up in listening tests , either as muddyness in bass or something in the vocal range that you can't quitee put your finger on , but it wearing over listening time !!
Some fundamentals to remember. The filling of a space with absorbent wadding is there to reduce the internal standing waves that get energised by the speaker and augmented by the parallel sides of the box. This problem will be most noticeable where the internal height, width and length are half wavelengths. It's considered that the best place to put the wadding is in the centre of the acoustic space. Reducing the standing waves minimises the energy transferring to the cabinet sides reducing the colouration. Cabinet wall thickness, bracing and damping is about minimising the energy transferred from the inside to the outside of the box. Either make the panel very stiff and possibly move the problem colouration up in frequency into the region where the ear is more sensitive as a consequence, or allow it to flex slightly with thin walls as long as it's very well damped, thin ply with bitumen dampening panels for instance, keeping the resonance low in frequency where the ear is less sensitive. A quick tap test on the cabinet sides will tell you which is which. Either way you are still going to get some radiation of sound through the loudspeaker diaphragm from the cabinet interior.
Lots of bracing AND mass loaded vinyl applied to all panels. I did similar measurements about 5 years ago, as you did here. Really noticeable audible differences.
Its subjective, lol. I know people who listen to music that rave about the sound and all I hear is high pitched garbage or so much bass that it drowns out everything. If you like it, fine. But if an overwhelming majority tell you its shit then you have a problem. Good talk John.
I knew that. A furniture plywood is the best for me. With an automotive insulation membranes. But a disadvantage (that was the reason) is a humidity sensitivity. If you keep your speakers away from water, you'll be good with a wooden box in opposite to a paper one.
Calculate, build, measure == engineering. You might like calculating the expected panel frequency to see how close it was for your build. Really great to see the build and measurements. I build boxes small enough that the lowest cavity resonance is above the range I will use that driver. I do the same with the panel resonant frequency. If the panel is thick enough and small enough or braced sufficiently, the first resonant mode of the panel can be placed above the range the driver is used. Stuffing the box with very dense wool or fiberglass completes the package. A fully non-resonant enclosure. You do best to make the box the shape of a half cube with the driver centered on the large square side. I don't think you can do better than that.
What would be interesting would be larger dimensions, which would create greater spans, thus creating larger vibrational areas. Say, 48" x 32" x 32", creating a more concert size speaker cabinet. Such a small test sample as the one herein, will automatically have minimal vibration, just because of span. Thanks much for your test! Enjoyed seeing the data..
Interesting. I've been building speaker and subwoofer cabinets from solid pine "project panels" for years now. It is very light weight and much easier to work with compared to MDF.
This is a great test in the analysis, but I think that maybe clamping the speaker box that way, and using it for every test, leaves only the front panel where the speaker is mounted as a variable. Internal reflections could show more with no clamped boxes fully made of the same material. Again, it's still a great test, cheers.
Thanks John, this is very opportune for me. I'm about to build a pair of mass loaded transmission line enclosures. The design is heavily braced and the designer just mentions 'good quality multi-ply' . So I've been agonising about 18 mm Baltic birch or hardwood construction ply. Both are expensive in the UK at present, Baltic birch especially so and it's not easy to source. So I've been thinking - will I hear the difference with ordinary ply ? Sure it's lighter and less stiff than birch, but .... So I'm going to use 'regular' hardwood ply, not Baltic Birch. It'll be veneered anyway. Really enjoy these audio excursions.
You might also try laminating your 'regular' plywood to a thin MDF sheet, using lots of glue and pressure. The result will be substantially better than the best Baltic birch.
@@scottgoodwin9162 Thanks - I'd considered that too as a means to simplify the box construction away from mitres to simple butt joints and using mdf to skin it, helping to mask 'telegraphing' of the then exposed ply layers. The result would be veneered 0.8mm . I've been caught out with veneering ply before. The 'telegraphing ' can appear months after..
Interesting results. The only issue with plywood is the strength of the joint with end grain if you are just using glue; there are ways to deal with that though. I used plywood for my Infinite Baffle manifold to get strength. I would not want to hang 4 15" drivers to a MDF box attached to floor joists. I did glue and screw it though, and with opposed drivers, a lot of the energy induced is cancelled out. Thanks for doing the test. MDF machines nice, but is a PITA dust wise....
Bracing lifts the resonance higher, where stuffing and damping can be applied easier and more effective than on lower frequencies. Lower frequencies require brute force to be produced and to be damped.
Perhaps lining the inside of the box with a sheet of polystyrene, or with rubber or leather. Using damping wedge shapes. Increasing the box wall thickness. Lots of fun experiments.
Interesting, thanks. Though I'd have to imagine there would be much more substantial differences with a large box speaker. With panels this small, screwed down this rigidly, you could probably use almost any reasonably stiff material and get similar results.
One advantage that MDF has over the other materials is in the realm of finishing, be it veneer or paint. Since MDF is so smooth and uniform, it's a great base to put a veneer on - no low or high spots. Paint, especially if you go for glossy, really does well on it, as long as you properly fill the exposed edges. I've used anything from thin super glue to sanding sealer followed by a light sanding to get a surface as smooth as the face.
I have tried to lay an automotive finish on MDF and it can be done but the material is so soft that it's easily ruined from handling. Also, none of the wood based materials are really flat, especially after clamping and gluing. You can get the same results by using spray filler to encapsulate the ply with a much harder end result. I got the idea from seeing the wilson factory and their "gel coat" which is actually polyurea or polyester coating. Once it's got a thick layer it's easy to block like a car. I would still wait a month for the material to settle down before primer and final sanding.
When I build my rather large subwoofer boxes (home theatre), I lined the panels with a mixture of drywall mud and white glues, about 1/2 thick. It's heavy but the box responds, when struck, like hitting a rock. The material I used for the panels was 3/4 " mdf. I used simple 1 x 3 as bracing.
It looks like subwoofers would work better with mdf it read higher in the low hz 100 down. But I don’t like useing it eather every were you hear all the great things about birch. So that’s what I’m gonna use for a 15 sundown I like the thought of being able to stain and clear the wood an how good it will look ! The caricatures of the wood grain with all the detail wood grain has it’s beautiful! They say it’s stronger and lighter then mdf so I’m gonna find out this is a gr8 video and thanks for sharing it nice to have this info I’d like+to see if there would be a major difference with this for lower frequencies like with a subwoofer from 20-250 hz I think I’m gonna do the rubber inside my ported box’s but sealed I just paint them heavy I could tell the difference between painted and not also is I put pillow filler in one seemed like it was a better sound but I’ve only built subwoofer enclosures most sealed but I’m learning ported ones !
Porous vs. Non-Porous smooth. Wood vs Glass or Glass-like does have an impact on cavity resonance, frequency response. As a simple example, take a high end classical guitar, the type of wood will have an impact on sound, but it is also a matter of volume, geometry and in the case of speaker enclosures the electrical components (drivers and X-over network). Formica applied with contact cement, as a finishing laminate over MDF or Plywood, in my experience adds a more solid enclosure which holds sound rock solid provided the box is sealed, ported and tuned properly.
This is where blind testing comes into it. But MDF is great cheap in lots of sizes you want to use and if you don't like the look, you can cover it, as most do. Unless you are going superhigh end and the wood you use is your selling point.
Zu Beginn des diy lautsprecherbaus gab es kein MDF in den frühen 80ern. Spanplatte! Massivholz in jeder Art war verpönt. Wegen der Eigenresonanzen. Multiplex gab es nur für PA. Eine gute Alternative war 2 verschieden dicke Platten mit unterschiedlichen Resonanzen zu verleihen. 19mm +13mm. Heraus kam ein wirklich brauchbares Resultat 👍👍🇩🇪
I remember well in the 70s all British speakers were made with chipboard. Then the BBC started doing tests on cabinets. They concluded that plywood gave a higher frequency resonance but was easily dampened by bitumen panels glued to them. Chipboard had lower resonance but was harder to remove. It was not long before a number of British speaker makers also started using ply with damping panels. Spendor, Rogers etc. These were very good sounding speakers, was it because of the ply or were they just better speakers?
The best results gives a sandwich of glued chipboard inside and MDF outside with veneer. Chipboard absorbs sound better then MDF. But MDF gives stability and robust construction.
I think the purpose of damping is twofold: First, it helps reduce the amplitude of standing waves and second, it adds to the mechanical resistance as seen by the loudspeaker. Thus, in a sealed enclosure, the lack of damping will necessitate a slightly larger enclosure for a given target Q.
Voids in the plywood is often used as a reason not to use it. But I've yet to cut into any that had anything inside to rattle, and I've cut through hundreds of sheets of plywood of every grade.
NOTE: This is to clear up some confusion over what I meant about bracing and damping:
Speaker building was always bracing and damping. But at some point the idea started that bracing alone was better, just using a lot more of it. Guys were still doing the traditional bracing and damping (like me), but you also started seeing these bracing only builds happening. The idea was to drive up the panel resonance high enough so that it wouldn't be excited and therefore wouldn't be a problem
I'm speaking 100% from a DIY standpoint, not from what the major manufacturers were doing.
Will making the entire box from the same material make a difference? Possibly, but I did what I could to take the rest of the box out of the measurement. For example the box was clamped down to my very heavy and stable workbench to keep it as stationary as possible, and help restrict the measurement to the panel itself. Yes the other panels were still vibrating and in turn that can affect the panel being tested, but it's the same for each of the different panels.
Each panel was exactly the same size - 8-1/2" x 12" with the screw holes in exactly the same places.
Why 30Hz to 2000Hz? I did some "warmup" testing prior to the measurements I made to determine the best range that shows the most relevant data. 30Hz because the speaker I used doesn't have significant output below 30Hz.
I used my ACH-01 accelerometer connected to REW to run the measurements. I made a special preamp for that accelerometer in this video: ruclips.net/video/o1Fctgs8CcQ/видео.html
My conclusions are that the material used is not a significant factor in how the speaker will sound. As long as what you are working with is of reasonable quality, you should not be able to hear the difference.
You may be able to imagine you hear the difference, though, and the human psyche is a powerful thing to overcome. If you believe MDF sounds dull and sluggish, and Baltic birch plywood sounds lively and fast, then it'll be very difficult to get past that and you should use the one you think will sound best.
As for bracing vs damping, I think both are valid. Use bracing to reduce panel size so that the damping will be more effective. The rationale of those that prefer bracing alone is that the damping "smears" the response. Much like above, it'll be hard to get past this idea if it's what you believe, so best to go with what you think is better way.
Very interesting results .I would like to see tests of clds.i read years ago about someone who glued sheetrock to the inside of the enclosure panels.
While listening to you explain damping vs. bracing on the video, I think we understand damping differently, and I was curious if you mis-spoke, or I mis-understood you. There aren't very many times where I think you are wrong, or disagree with you, so I thought it was interesting. From my reading on the subject in the past, the stuffing, or damping material is to slow down the sound waves to enable a smaller than the math shows box to be used. In a sealed enclosure this is done by stuffing the box, and in a ported enclosure you more so line the box with stuffing so as not to miss up the air flow from the box to the port. Niether of these things have anything to do with panel damping as far as I undertand. Now if you were too put some type of butyl paper, or the like on the panels, that is meant to damp the panel. But those things would actually drive the resonant frequency down (edit: of the panel) due to adding weight. The bacing on the other hand would drive (edit: the panel resonant frequency) it up, I agree, due to making the vibrating panel smaller. This was a pretty sweet test, that changed my mind alot about MDF being the superior box material for sound deadening. Prior, I had only read opinions on the subject, but seeing a straight up test, kind of changes things. I don't know how well these speaker videos do for you but I for one enjoy them, and this one especially was interesting. You keep making em' and I'll keep watching em'.
@John Heisz - Speakers and Audio Projects
Nice test, John!
*EDIT: I just watched your speaker enclosure "Stuffing Comparison" video so disregard some of my info/points below*
But, I would not have clamped the enclosure down, at least I would not have clamped to the TOP of the enclosure, as that will SIGNIFICANTLY damp and reduce the top panel vibrations and change the overall resonant frequency.
Those clamps will absorb A LOT of the energy and "normalize" the differences between the various panel types.
Instead, I would have built the enclosure with a base panel (the bottom panel that's sitting on your benchtop) with ends that extend past the vertical side panels an inch or so on each side to use as your clamping points or "wings" at the base.
This will still "damp" the enclosure overall and change its resonant frequency, but would not have affected the resonance of the top panel nearly as much as the top clamping points did!
And to be fair, in the real world none of us "clamp" our bookshelf or tower speakers or subwoofer enclosures to the floor or any other supporting surface, so there's that. ;-)
I also wish you had taken nearfield measurments of the actual Acoustic Response of the Speaker itself in REW using the different panels with & w/o the internal acoustic damping material using your miniDSP UMIK-1. That would easily show if any of the changes were actually audible or changed the acoustic response of the driver's output. ;-)
Obviously, the overall size of the enclosure/cabinet will drastically affect the frequencies and amplitude response of the various resonances significantly.
And with each unique enclosure, you must also take into account the potential internal resonances due to standing waves that will occur due to the specific HxWxD dimensions of the enclosure.
IMO&E, using good internal bracing and a SOLID, DENSE Mounting Baffle for the drivers is important.
The best performing enclosure I have built in terms of being resonance-free were from 1" thick HDPE or UHMW plastic panels. Obviously quite expensive and as heavy as an elephant, though! But this material is nice because it can still be cut, worked, & shaped easily using your standard woodworking tools...tablesaw, router, drill, sander, etc.
You must use fasteners and not adhesive to build the enclosure, but you can use thread taps and machine screws to construct and secure the enclosure panels and make them infinitely removable.
I use a 1" wide by 1/32" thick foam self-adhesive gasketing tape between each panel's adjacent connection surface. Of.course, all of your cuts must be perfectly square and smooth in order to seal the enclosure.
Finishing this type of cabinet and making it aesthetically pleasing is the tough part. :-(
IME, I have found natural wool fiber to generally work best as internal acoustic damping/stuffing material. Danny at GR-Research also sells a self adhesive backed sheet foam damping product called "No-Res" which I have found to work well to line the cabinet walls themselves. YMMV
The natural wool, polyfill, fiberglass, or mineral wool batting or "loose fill" helps reduce both the mid-to-high frequency panel resonances, as well as raising the QTC of the enclosure (making it effectively up to ~20% larger overall) by converting vibrational energy (sound waves) into low level heat. Google Search, "Make A Small Box Act Like A Larger One With Polyester Fiberfill By TOM NOUSAINE".
As you alluded to, I will often use a Constrained Layer Damping sheet material ("CLD" tiles/mat/sheet) such as Dynamat Extreme, ResoNix CLD Tiles (best performance), or Stinger's Road Kill Ultimate (which adds a foam isolation/decoupling layer) to the inner panels of the enclosure to dampen resonances and reduce the resonant frequency peaks.
CLD "Deadener" or "sound deadening mat" is made using a butyl rubber-based compound (usually with mica and/or talc added) that is topped with a thickish aluminum foil type "constraining layer" and has a self-adhesive-lined backing on the butyl side.
This combination of materials works extremely well to dampen panel resonances. To save on materials and costs, attaching a smaller piece of the CLD sheet or "tile" in the middle or center of a resonating panel works nearly as well as lining the entire panel with the CLD sheet.
I have also used "Green Glue" acoustic damping adhesive to attach and line the interior panels of enclosures with Alphasorb Wood Fiber Acoustic Panels which works incredibly well, though you have to design and build the enclosure larger to offset the reduced internal enclosure volume.
To learn more about the potential audibility of enclosure/cabinet resonances, go to the *Erin's Audio Corner* RUclips channel and watch BOTH of Erin's objective measurements (Klippel Analyzer/NFS) & subjective listening reviews of the *Klipsch Heresy IV* loudspeakers. Many of his other speaker reviews cover this topic as well.
Basically, a.simple impedance sweep measurement using an inexpensive DATS V3 unit will show any resonances as "blips" or "bumps" in the impedance curve or plot, and they will correspond to anomalies in the on- & off-axis frequency response.
Keep up the great work!
You've only measured 1 side of a 6 sided enclosure. What you've measured is the characteristics of that one side. When coupled with the face, side, bottom and top, they'll react differently unless you've produced a perfect cube.
Another school of thought in speaker building is many designers WANT the face (I forget the technical term for it, the panel the speakers are mounted to) to resonate and produce sound on their own. This panel can be tuned to augment the actual speakers and produce a desired sound.
Also: who uses 1/2" material to build a speaker? If you're building tiny bookshelf speakers I can understand it but for any serious main speaker? 3/4" is the norm, 5/8" at the bare minimum. If you're using an 8" woofer you MUST use 3/4" due to the sound energy it will produce.
To be accurate, you really should build the entire enclosure out of the same material. What you've done is like testing the water quality of a lake by testing a sample at one end, near the shore where your cottage drain pipe is located. Go to the source of the water, a spring, and the water quality will be different.
I would love to see a box made or corian
That was a really interesting demonstration. It really confirms the long standing tradition of MDF boxes, stuffed with batting.
Your findings are very accurate. Bracing helps more than dampening, but both are useful and necessary. Dampening will reduce the amount of energy reflected back into the cone. Bracing raises the resonant frequency of the panels.
I'm enjoying this whole series John. We used to spend hours in the warehouse A/B comparing all kinds of things. One of the breakthrough days was when we got a crossover that could time align the drivers in a horn loaded array... The pressure level differences were quite notable.
About 40 years ago a friend of mine had his brother build him a pair of speakers. The cabinets were plywood and the drivers were from Radio Shack. They stood about 3 feet tall, 2 feet wide and a foot deep. To this day they are the best sounding speakers I've ever heard. I need to ask him if he still has them. My guess, the drivers have turned to dust by now, but it would be a cool re-build with modern drivers.
Probably already commented on, but my guess is MDF is used mostly because it's always flat and takes less work to finish for painting/wrapping. Great video!
also, is more consistent and homogeneus material; plywood quality can vary greatly in the same batch production
Baltic birch remains amazingly flat as well.
No. MDF is used because it's cheapest and still works fine for speakers.
Excellent and informative!!! I was a master installer at a high end shop for 9 years. Our material of choice was Trupan cabinet-grade MDF. Generally the enclosure was glued and screwed, then ALL inside surfaces were painted with latex paint to prevent 'breathing'. For aesthetics all non-upholstered areas were painted as well. The material would leave talc-like sawdust and just EAT router bits and bearings if not fed or cut slowly.
I am thankful for this ...I was looking to repair my old Dahlquist DQ20 speakers and i didn't know what material to use ,.My beloved speakers got water damage and i want to revive them .So your effort has been what i needed to know ..
I always put stuffing in the speaker box to stop sound waves bouncing of the clean walls and repeating back onto themselves and the driver.
Remember when adding bracing you need to increase the volume of the cabinet because the brace takes a lot of volume up.
I made a set of speakers years ago that had angled sides, multiple braces, stuffing, one coat of paint on rubber membrane them a second coat of rubber with sawdust added. Cabinets made from 18mm MDF.
Still listening to them today.
Good work on the experiments, it's the only way to really find out!
OUTSTANDING VIDEO!! Wonderful to see some empirical testing on enclosure material resonance. You confirmed a number of longtime observations I've made myself. Personally I've found that a combination of bracing (of different types used in the same box) and the use of laminated panels is very effective at eliminating resonances. If you glue a thin (1/4 - 3/8) panel of (quality) MDF to a Baltic birch plywood panel, the result is amazingly stable. You have to use a lot of glue, and make sure it is uniformly clamped together, but it's worth the effort. Many of the high-end speaker manufacturers utilize composite layers of different materials to absorb resonance. The key is using materials with different *densities*. When the energy hits material A it bends at angle X, for example. As it passes from material A to material B (of a different density), it bends again at angle Y and so on... Each change in direction absorbs energy.
I'm an instant fan of your work, thank you!
This was great and hopefully many will also learn about measurement, interpretation and practical application, (as opposed to folks going weird with the end-grain video).
Fascinating! THANK YOU for doing all that analysis and sharing results!
Ages ok (mid-80s, I guess), a friend of mine had an old pair of speakers, something from the 70s, pretty standard stuff, just like the rest of the equipment.
The drivers had paper cones with stiff suspension, the soft "rubber" wasn´t really standard at the time those were made.
Those speakers were ok, but down low their resonance made them sound quite undefined.
After a little thinking about it, we removed the drivers, measured the inside dimensions and cut a few pieces of wood, about a 16th oversize, wedged them between the centers of the panels and remounted the drivers.
The low bass got much better, it sounded much more responsive and defined.
It still was far from comparable with higher-end contemporary stuff, let alone modern equipment, but it was definitely an improvement.
back when i studied sound engineering and was into speaker building, my conclusion was the material is not as important as the construction. meaning adding bracing reduced resonance
one though i had on bracing was to not divide areas in half but use perhaps 1/3 etc to not get two areas that have the same resonance since this in my experience makes the resonance multiply by each surface with same area. also overkill is always good :P ply or mdf with 1/3 bracing, damping with foam and filling with poly can be combined for the best :) really enjoying these vids!
One thing that these measurement highlight is how small overall the differences actually are. Like having a microscope and seeing things at 100X. For each of these sweeps, I couldn't hear any difference at all.
It's like every other technical subject, where these minor differences often get magnified and given more importance than they deserve.
Great video! Good to have actual measurements to see the difference so I can use veneer plywood instead of mdf. One thing to try is using stick on vibration damping material used in vans to see how well it would work with wood.
@@llee4225 I don't see why it wouldn't work. If it can help reduce rattles or in some cases rid of rattles and squeaks all together in some older vehicles you'd think it would work inside a speaker box also. I've actually been pondering on replacing the old original damping material in my vintage Pioneer CS-53's with some DynaMat or a quality equivalent to see what would happen. :)
@@llee4225 I think comparing how well it works on large thin steel panels, compared to a thick piece of wood panel, doesn't work to well. I'm guessing if he did a comparison between this test result and then added dynamat or the like to each panel and did the same tests there wouldn't be much difference. I think the wood is WAY more damped than the van panels to begin with to a point where it would be a pointless expenditure to purchase the dynamat.
Agreed that it does wonders in a van though.
thanks for posting some actual testing verified with results. I like your questioning attitude. As for the resonance issues if you look at the speakers often used in sound reinforcement in live performance and DJs they are mostly molded plastic and iff the equipment is set up correctly for the room some of them sound pretty dam good . Like any musical instrument like all the horns wood winds and brass it is primarily the size and shape of the cavity not the silver and brass that make the difference between OK and great sound.
This is a great project with good discussion.
I would suggest that you could test the speaker cabinet in a free-free condition by supporting it on some soft foam. This would also eliminate the boundary condition created from clamping the wood panel through to the bench - this will likely affect the panel resonance and modes.
These acoustical experiments are awesome. I was always taught thicker/denser the better and add bracing
In a quiet well designed listening room with people willing to concentrate on critical listening, they will hear slight differences I think. My friend and I build speakers and for a test we both used the same 5" woofer and 1" tweeter and built 4 different boxes with the same air volume for bookshelf speakers. They all sounded different but the best one was built from laminating 3/4" birch ply and 1/2" MDF together for a 1.25" thick cabinet wall. The idea on that one was making a traditional rectangular speaker but with complete overkill for cabinet rigidity and using plywood and MDF with a layer of contact cement would provide some extra damping for the cabinet wall it self. Another one was made from laminating many sheets of 1/8" MDF into an oval cabinet. Those two examples were the most different in sound. The oval one was ringing as if some bass and mid bass frequencies were blending together, The 1.25" thick one seemed much more refined with no noticeable ringing and a tone/frequency sounded like it was more true to the source track. No braces were used in those but I've added bracing to larger speakers before and that does seem to work better in general.
Thanks for documenting the experience, some thoughts come to mind. A loudspeaker enclosure is a 3D structure which is most often heard also mounted on a stand, the resonance modes of such a structure are not necessarily the same as the resonance modes of a single panel firmly attached to a heavy woodworker's workbench. Plate theory offers good ways to predict the modes of a rectangular panel made of isotropic material, but the analysis of the "3D" modes of the entire enclosure on a support is much more difficult to predict. Add to this that opposing panels could resonate additively and radiate sound into the room, but could also have modes in which they move identically, hence subtractively, and therefore do not radiate sound at a distance. I fear that it will be necessary to build an enclosure entirely and measure the accelerations of the opposing panels to be able to accurately compare the influence of the materials used on the distant sound field. Would be super interesting to also add other type like HDF, Bamboo ply, CLD with polymer, ...
I remember that sound. I worked at Allison Acoustics in the '80's. Started out doing production. Worked my way up to testing. We tested components and finished speakers. Our cabinets were MDF with a fake veneer on the outside. Inside we placed a small amount of fiberglass.Never used isolation rings on the speaker basket or bracing. Dr. Roy had the cabinets made to his specs. Never tested cabinets. Interesting show.
Cool vid man. Thx for taking the time to build the experiment and edit down to such a pleasurable video. Man of many talents. I think I say that every time I watch something you put out. Lol
I made two pairs of speakers in my life. For both of them I used 3/4" MDF and as a "veneer" used 1/4" plywood (oak or birch). Solid as a rock.
For a couple 8's, @250watts, I built mine with 1/2"MDF and 1/4"veneer. Like you said, solid as a rock, and souy great too.
I used 1.5" solid walnut butcher block for the baffle and a layer of 1/2" mdf bonded to 1/2" birch ply for the rest. Sounds great. I think the thick solid front contributed the most.
Looking at the location of the bracing, it seems pretty much in the middle of the box - so any panel resonances would be be at the same frequency above and below the brace, giving a single peak which is the sum of both sections.
What I might try is offsetting the brace so it’s not symmetrical - I’d have to do the maths but my guess would be that the golden ratio might offer the best performance, giving two peaks at different frequencies which don’t sum to a higher peak like they would for a symmetrically placed brace.
Thank you for all the great work, investments in time, energy, funds and skillset required, to accommodate the information you are presenting here! Much appreciated.
Bracing panels forces us to think about the vibrations of the panel itself rather than the resonance modes of the internal air volume in the box. If we put reinforcements in the main resonance modal lines of the panels (1/2; 1/4, etc) , creating symmetrical divisions, we will have 2 or more identical zones resonating at the same frequency (+3dB reinforcement). That's why it's recommended that the reinforcements be located in asymmetric divisions of the panel in question. You also have to think about the size of the resulting sections with the division. If a 12" panel is split at the center, we will have 2 resonant 6" sections; the ideal is to have zones no larger than 4 " (this pushes resonances much higher than 1kHz, which eventually makes their absorption easier by passive means (foam, textile fibers, etc.)
Several studies show that the vibrations of the panels are not perceived if they are 30dB below the main radiation (woofer), in the bass region (below +-300hz), the teorical "limit" is a little less (correlated with sensitive hearing curves)
(the BBC did important research in the 70-80s for the development of its monitors, there are excellents papers on the web about the topic)
I wish I could understand this a little better. Quite interesting.
@@nerdynumen something about vibrations, damping materials, etc
downloads.bbc.co.uk/rd/pubs/reports/1977-03.pdf
@@nerdynumen Its the BBC... no doubt they lied about the results ;)
I love these measurments and experiments bcuz these are about science and physics PLUS audio. Thanks for sharing.
The most incredible part of the whole video is that he found a piece of Baltic Birch 😮
🤣
I've never had an issue getting 13ply Baltic birch bb/bb grade🧐
It was nearly impossible here in KC. Everyone was out until recently.
True that.
I build speakers too and the crossovers. I use the 20mm pine ply for my speakers and I brace them with thin dowel by glueing the ends to the box panels across the speakers inside (several of them front to back and from side to side). I did it to save internal volume but maybe it's better than normal bracing, going by your results. Interesting that it makes such a measurable difference. Great work dude. Cheers Big Ears!
I like your shop! You can tell a lot about a carpenter from the way he keeps his tools.
John,
I love your programs !
You created in me, a big interest working with wood... I think I'll love it, as my hobby...
Thank you so much !
There was a thick ceramic paint that worked well back in the mid to late 80s. Then there is the dampening material used in cars. There is something called no res that is pretty popular now. As far as bracing goes, it works well also, but it works better if it is rounded over on any openings and where it isn’t attached as this tends to not allow resonances aggravated by the right angled surfaces. Opinions vary on this but my research backs up the rounded over bracing as opposed to that which isn’t rounded over. The materials used were mdf so things may vary with plywood. Baltic birch is very good for cabinets, but not so much for speaker enclosures. MDF is more dense and has better damping characteristics when treated with surface coatings or other dampening material. Most manufacturers don’t bother with any dampening as this adds to cost. Failure to use any dampening causes resonance issues and DIYers and Modders have been doing this for decades. It isn’t a mystery.
My initial guess would have been that particle board would be the worst, with OSB and various plywoods in the middle and MDF the best, so this seems to confirm most of that. I also remember some inexpensive speakers from the 1970s with dense Styrofoam enclosures that sounded much better that I'd have expected: not much mass, but maybe a lot of damping; a test on that would be interesting.
Thank you. I just build a box using 3/4" MDF, and I hate using it because it splits so easy with screws, even drilling a pilot hole, so I'm going to go buy 3/4 oak and try again.
Try using confirmat screws, they’re specifically designed for Mdf and particle board
Try using woodglue before you put a screw in, but with little saw dust...
Absolutely great video. I've used 3/4 cdx plywood mainly on speakers over 8 in. and used shag carpet as a liner. (ha ha ha showing my age).
Solid experiment. I am in the process of designing and building some sealed 15" subs. my plan is to use 3/4" BB and laminate a 1/4" MDF to the outside.. My thinking is that the BB is lighter than MDF so the subs won't be as heavy as using all MDF, but the MDF outer layer will make the veneer application easier.
If you use a slightly soft adhesive, having different materials will actually result in better damping.
You are right on track. Use lots of glue and pressure when gluing the materials. The result is very good at absorbing resonances.
Very interesting, John!
I’m guessing the pine ply had the lower ringing due to the varying thickness of veneers, which make each layer less sympathetic to adjacent layers.
I like to use two layers of granite, one being 3/4” and the other being 5/8”, laminated with a layer of 1/4” lead sheet.
Let the tone wood debate begin😁
Thanks again for taking the time to test and share.
Awesome!
About 40 years ago I built a set of 3 way tower speakers using 1/2" particle board with 1/4" Luan plywood laminated on the outside with for a nice looking wood finish. They are still going strong and the cabinets are still solid as a rock. The only inner bracing was a divider between the woofer and the midrange/tweeter section, to make the woofer section the right volume for the speaker that was used. I also put fiberglass insulation in the woofer section. I know particle board isn't really desirable for speaker cabinets, but even at high volumes the cabinets show no signs of vibration. I keep thinking that I'll rebuild them some day, but they've been such good little troopers.
Actually, there's nothing wrong with particle board. Hundreds of thousands of speakers were (and are) made from it. It's no better or worse than most other materials used to build speakers.
👏👏👏 for you! For me a very valuable conclusion: "tone wood" is a thing, in this case it's pine! Even if it's plywood!
So spot on about everything effects the sound even your mood and blood pressure hahaha!!
@IBuildIt
A few years ago I renovated a pair of heads (MDF) with a 12" bass and a 1" tweeter with a 30cm horn - with a multiply (9-ply) beech wood exterior and a vented cabin.
I dont like MDF, it's really cheap material and parts of the corners were broken off, I remade it. There was a big difference: clear, clean, no booming, that's why I decided to use the next cabin - RCF 18" ventilated (approx. 100 cm high, 70 x 70 cm), old: MDF, new: Mulitply - also there a big difference in the sound!
I think because the MDF is softer, and the Multiply is much stiffer, minimal bending, so in my opinion there is less cushioning and more comes out of it! The best part is that the veneered surface makes it easy to get a brilliant finish, I use epoxy resin as glue, after 10 years no problem, no shrinkage, no leaks - and 3 coats of epoxy resin outside - the best result you can expect your work can achieve!
My last project was an Electro Voice Eliminator - a 2 x 15" cab - a big deal, a lot of work - but in the end it rewards me doubly every time I play with it.
On my last speaker building project I used a knotty pine butcher block style project board from Lowe's. It's relatively inexpensive and beautiful with a bit of oil on it. There's no reason to fret about the material resonance if you address the resonance with bracing and damping materials. I lined the largest sections of panel with asphalt/rubbery type damping sheets, then used acoustic foam, then poly-fill. The result is a plenty-quiet cabinet and a beautiful knotty pine butcher block finish that required no nonsense to "finish." Just a rub down with some oil to give them a bit of rustic sheen.
Great video! Thanks for taking the time to create this video.
Interesting. Thanks for sharing these tests. Valuable info.
Very interesting and very informative. I never liked mdf. It always seemed to not be stuff enough and therefore would require a lot more bracing. The effect of insulation on high frequencies was interesting. I would assume that it would be due to dimensions of the box creating "room" modes inside the box? Thank you. Very helpful.
It's a good ides to knock down those higher frequency "nodes" inside the box with damping materials, otherwise they will "ring" back through the cone and sometimes the port. Ideally speaking, we want to damp most of the energy coming off the back side of a driver down to nothing. Exception being low frequencies that we might be intentionally exciting a port or passive radiator or horn resonance with.
I’m pretty new at speaker building. I admit that I was surprised at how cheap most companies build speakers. Fairly expensive(for me) brand names tend to have cheap speakers, thin wood, light gauge CCA wires but made the cabinet look real nice and fancy. I ordered some actual Pioneer speakers, crossovers and build 1/2” thick sealed but ported cabinets and used copper wire for 1/8 what a nice pair of Pioneer cabinets would cost and they sound good. They’re not as pretty or expensive looking but genuinely sound better than the most expensive speakers Ive heard. Of course, the source has a lot to do with it but I am comparing these I build with a $800 pair of Fishers I own.
I like experiments like this. I believe the materials would have shown a greater difference if the accelerometer placement was on the speaker baffle itself. I realize that entails more work. Also, it would be enormously interesting if you had also tested a constrained layer damping material applied to the inside of the baffle such as Dynamat Xtreme. Also, there are manufacturers such as Magico who make cabinet enclosures out of billet aluminum and carbon fiber. They also apply damping materials such as No-Rez to the insides. Thanks!
Speakers sound so much better when they look better!
John, love the channel! Great Work! This is the kind of videos we need!
Interesting. I've often wondered which material is best, and now I realize that I bumbled into the better one with MDF for the couple of pairs of speakers I have built. One thing that kept distracting me were those wooden wood clamps! Those are sweet. Now, I'm thinking about building some.
I mostly don't know what I'm watching but thanks for the video John!
Another top tip is to laminate a panel of mdf to the inside face of baltic birch. This improves(reduces) time of resonance. Bracing works by lowering amplitude of resonance and shifting frequencies further up.
Creating sub panels by multiple braces unequally spaced makes them effectively different sizes and splits frequency of resonance hence reduces amplitude of each specific frequency. Equal spacing creates lots of sub panels of similar frequency so doesn't reduce amplitude which becomes additive.
Using 5 braces has a similar effect on resonance amplitude as doubling panel thickness so increasing nr of braces to more than 5 has no advantage over simply doubling panel thickness except that the larger the cab the lighter you can make it by upping nr of braces. Using visco elastic damping membrane on inside panel faces drops resonant frequency and lowers amplitude and time of resonance. There's loads you can do. As speaker size increases so mass increases and structural integrity becomes more important. This is where baltic bitch ply is superior as it has greater integrity through higher tendsile strength and greater resistance to shear as well as splitting compared to mdf.
I was considering this option as well, not only to tame Birch but maybe even something as radical as the grains from sweet gum that I have plenty of around here and would like to put to good use.
Tried bamboo?
I've made a couple of tower speakers using 3/4 inch solid white pine, braced and lined with fiberglass. To me they sound great.
Wow! It’s very nice to know this! Now I can just build me a sub box using the cheaper plywood
What a breath of fresh air! Now on to the most sacred of cows, the crossover. Can off the shelf crossovers of decent quality with properly matched drivers produce great sounding speakers? I think so, by using your ears in matching the drivers, like designers did in the old days, must have anyway.
Interesting results. Thanks for sharing. Amazing work sir.
Nice to see your wordworking dovetailing :P so well with scientific examination with regard to speakers and sound issues. Well done info!
I found this interesting. I use MDF instead of particle board, because I found MDF much easier to work with (much less chipping and much more reliable at holding screws).
Cheap plys and "particle board" would be more prone to chipping.
I feel that plywood dust may be a little better for you than MDF dust ;p Not that either is great to breath
Interesting test. This pretty much confirms what I have heard by ear, in that there isn't an audible difference. I switched years ago to mostly baltic ply, for the reason that it's consistent thickness for the CNC, and that it's much harder than mdf, making a more durable end product. MDF dents and bends corners too easily. I also played with corian and phenolic, but again, the advantage wasn't sound, but rather a more stable material for finishing. If you want that Wilson finish you need to lay down a really thick layer of spray filler to encapsulate the joints, then wait months while the material settles down, swells, shrinks, and moves. Then and only then do you dare block it for primer. That said, take a close look at a wilson and even they have issues with their materials. You will plainly see the joints through the automotive finish.
Nice video John! Thanks for always sharing with us!💖👍😎JP
Hi, I used to work for a 'name' top, top end hifi company and for hifi plywood is superb, plywood front and back with chipboard 'wrap' (sides, top & bottom) is great but MDF was absolutely awful! It howls and has huge upper-mid overtones.
I built a pair of small satellites and a pair of large bass boxes using 3/4" oak laminate plywood and they worked out quite well. My concerns with using plywood are twofold, first, that they don't lend themselves well to gluing on bracing on the inside of the panels, since the brace would be glued to the first layer of plywood only, and second, that over time the plys may begin to separate and rattle. For my latest boxes, I went back to MDF, since with the oak laminate material, I still had edges to cover, and with the MDF, I used oak laminate sheets to cover the entire surfaces of the front, top and sides. For internal damping, in the past I have glued carpet padding to the inside panels using carpenter's glue (called Powergrab) applied to several places on the padding. For the last project, I purchased water based roofing cement, and brushed it on both the inside panels and the carpet padding, applying quite a thick coat, and glued the padding to the panels, this provides both dampening of the panel and absorption-diffusion of sound waves inside the box.
INice video, so important to actually have tests and measurements. Interesting when you have ultra high end audio where concepts are brought to reality often. Totally having inert boxes has been achieved but some find the resulting sound a bit analytical guess many wants to hear favourable resonances to a point so now many speakers are designed specifically with resonances in mind maybe not as much as Harbeth boxes.
you are the only other person besides myself who seems to be aware that mood has a very real effect on how "tone" or anything really is perceived. Do only the Snake oil salesmen know this too? haha
Top secret tip:
Glue together full sheets of 1/2" plywood + 1/4" MDF board with a synthetic rubber based adhesive.
Rip and cut panels with regular tools just like using a thicker board.
Use plywood outside for durability & MDF inside for good damping.
This combination has, by far, the best properties for nearly eliminating cabinet resonance.
Beats every other type of wood. The only thing better is rubber reinforced concrete. That stuff is impossibly heavy though!
That's not top secret, it's constrained layer damping - CLD.
@@IBuildIt So THATs what CLD means!! 😂
I'd only ever built speaker boxes the boring way (MDF, glue, screws) until I started investigating open baffle speakers.
A few years ago I saw someone build a box with CLD panels (various other techniques employed as well, for mounting a measuring instrument I think), it was ultra-quiet inside. You could put a decent BT speaker inside and barely any sound got out 😂😂
So I went ahead and build a few open baffles, recalling whatever I could from the way this box was built.
Admittedly, my understanding of acoustics & my woodworking skills are quite basic. But the resulting OB speakers were pretty spectacular to listen to. (They're downright ugly though, mostly made out of a combination of whatever wood I have on hand)
Haven't seen too many folks use the technique on RUclips though, hence the "top secret" bit 😂
This type of cabinet is used in the new Mission 770 speakers.
Finished my baltic birch tonewood speaker cabinet.
Can't wait to set this bad boy directly on the top of my desk without an iso pad, backed right up against the wall as tightly as possible in my untreated sheetrock room with oak flooring. Just got a new subwoofer too. Points straight at the floor and is 2 inches away from it right from the manufacturer like they all do for some reason.
Tuned each face to 432hz with my chakra. Also everything I used is plugged straight into the wall instead of a power conditioner to get that organic sound.
I worked for over ten years in a plywood mill. There are several differences between pieces of plywood. They are not always solid. Especially in typical pine plywood. There can be areas of void in the individual layers. The more layers that you have, the less that these voids will matter.
This is why I made my guitar amp speaker box out of fir and pine. But.. if I'm not mistaken, it's not the actual sound of the box that it produces while resonating that's audible, it's what the shaking/resonating of the box does to the drivers as it shakes in and out of phase with them. That's what you end up hearing as artefacts in the sound. The volume would have to be ear bleeding in order to actually HEAR any sound from the enclosure itself.
Thanks a ton for these tests. Kept me from buying into marketing hype for hifi speakers with hdf vs mdf. For example polk legend L600 vs arendal 1723 tower (non-s). Very much appreciated.
The same experiment was conducted on another channel I’ll Fargo the channels name out of respect to your channel. In their conclusion they found out that plywood was superior than MDF material and that marine grade plywood which is very expensive was the best to use to make a speaker box. The only problem is the cost of the marine grade plywood to MDF. MDF was about half the cost the MGP would cost.
The thing to look at is stored energy in a water fall plot , that tells the real story of what the cabinet does to the sound , stored energy always shows up in listening tests , either as muddyness in bass or something in the vocal range that you can't quitee put your finger on , but it wearing over listening time !!
Some fundamentals to remember.
The filling of a space with absorbent wadding is there to reduce the internal standing waves that get energised by the speaker and augmented by the parallel sides of the box. This problem will be most noticeable where the internal height, width and length are half wavelengths. It's considered that the best place to put the wadding is in the centre of the acoustic space. Reducing the standing waves minimises the energy transferring to the cabinet sides reducing the colouration.
Cabinet wall thickness, bracing and damping is about minimising the energy transferred from the inside to the outside of the box. Either make the panel very stiff and possibly move the problem colouration up in frequency into the region where the ear is more sensitive as a consequence, or allow it to flex slightly with thin walls as long as it's very well damped, thin ply with bitumen dampening panels for instance, keeping the resonance low in frequency where the ear is less sensitive. A quick tap test on the cabinet sides will tell you which is which.
Either way you are still going to get some radiation of sound through the loudspeaker diaphragm from the cabinet interior.
Lots of bracing AND mass loaded vinyl applied to all panels.
I did similar measurements about 5 years ago, as you did here. Really noticeable audible differences.
Its subjective, lol. I know people who listen to music that rave about the sound and all I hear is high pitched garbage or so much bass that it drowns out everything. If you like it, fine. But if an overwhelming majority tell you its shit then you have a problem. Good talk John.
I knew that. A furniture plywood is the best for me. With an automotive insulation membranes. But a disadvantage (that was the reason) is a humidity sensitivity. If you keep your speakers away from water, you'll be good with a wooden box in opposite to a paper one.
Calculate, build, measure == engineering. You might like calculating the expected panel frequency to see how close it was for your build. Really great to see the build and measurements. I build boxes small enough that the lowest cavity resonance is above the range I will use that driver. I do the same with the panel resonant frequency. If the panel is thick enough and small enough or braced sufficiently, the first resonant mode of the panel can be placed above the range the driver is used. Stuffing the box with very dense wool or fiberglass completes the package. A fully non-resonant enclosure. You do best to make the box the shape of a half cube with the driver centered on the large square side. I don't think you can do better than that.
Great test.
What would be interesting would be larger dimensions, which would create greater spans, thus creating larger vibrational areas. Say, 48" x 32" x 32", creating a more concert size speaker cabinet. Such a small test sample as the one herein, will automatically have minimal vibration, just because of span.
Thanks much for your test! Enjoyed seeing the data..
What about a denser hardwood rather than sheet goods?
Interesting. I've been building speaker and subwoofer cabinets from solid pine "project panels" for years now. It is very light weight and much easier to work with compared to MDF.
What about dense solid wood?
This is a great test in the analysis, but I think that maybe clamping the speaker box that way, and using it for every test, leaves only the front panel where the speaker is mounted as a variable. Internal reflections could show more with no clamped boxes fully made of the same material. Again, it's still a great test, cheers.
Thanks John, this is very opportune for me. I'm about to build a pair of mass loaded transmission line enclosures. The design is heavily braced and the designer just mentions 'good quality multi-ply' . So I've been agonising about 18 mm Baltic birch or hardwood construction ply. Both are expensive in the UK at present, Baltic birch especially so and it's not easy to source. So I've been thinking - will I hear the difference with ordinary ply ? Sure it's lighter and less stiff than birch, but ....
So I'm going to use 'regular' hardwood ply, not Baltic Birch. It'll be veneered anyway.
Really enjoy these audio excursions.
You might also try laminating your 'regular' plywood to a thin MDF sheet, using lots of glue and pressure. The result will be substantially better than the best Baltic birch.
@@scottgoodwin9162 Thanks - I'd considered that too as a means to simplify the box construction away from mitres to simple butt joints and using mdf to skin it, helping to mask 'telegraphing' of the then exposed ply layers. The result would be veneered 0.8mm . I've been caught out with veneering ply before. The 'telegraphing ' can appear months after..
Interesting results. The only issue with plywood is the strength of the joint with end grain if you are just using glue; there are ways to deal with that though.
I used plywood for my Infinite Baffle manifold to get strength. I would not want to hang 4 15" drivers to a MDF box attached to floor joists. I did glue and screw it though, and with opposed drivers, a lot of the energy induced is cancelled out. Thanks for doing the test. MDF machines nice, but is a PITA dust wise....
Bracing lifts the resonance higher, where stuffing and damping can be applied easier and more effective than on lower frequencies. Lower frequencies require brute force to be produced and to be damped.
Perhaps lining the inside of the box with a sheet of polystyrene, or with rubber or leather. Using damping wedge shapes. Increasing the box wall thickness. Lots of fun experiments.
Interesting, thanks. Though I'd have to imagine there would be much more substantial differences with a large box speaker. With panels this small, screwed down this rigidly, you could probably use almost any reasonably stiff material and get similar results.
One advantage that MDF has over the other materials is in the realm of finishing, be it veneer or paint. Since MDF is so smooth and uniform, it's a great base to put a veneer on - no low or high spots. Paint, especially if you go for glossy, really does well on it, as long as you properly fill the exposed edges. I've used anything from thin super glue to sanding sealer followed by a light sanding to get a surface as smooth as the face.
I have tried to lay an automotive finish on MDF and it can be done but the material is so soft that it's easily ruined from handling. Also, none of the wood based materials are really flat, especially after clamping and gluing. You can get the same results by using spray filler to encapsulate the ply with a much harder end result. I got the idea from seeing the wilson factory and their "gel coat" which is actually polyurea or polyester coating. Once it's got a thick layer it's easy to block like a car. I would still wait a month for the material to settle down before primer and final sanding.
too much effort for this poor material. Just take the better multiply, also less work, that's already veneered!
When I build my rather large subwoofer boxes (home theatre), I lined the panels with a mixture of drywall mud and white glues, about 1/2 thick. It's heavy but the box responds, when struck, like hitting a rock. The material I used for the panels was 3/4 " mdf. I used simple 1 x 3 as bracing.
Interesting! Did you have to do anything special to get the mud to stick to the MDF, and/or remain stuck to it?
@@scottgoodwin9162 The white glue made sure the goop stayed stuck. It's been 15 years and last time I checked, still good.
It looks like subwoofers would work better with mdf it read higher in the low hz 100 down. But I don’t like useing it eather every were you hear all the great things about birch. So that’s what I’m gonna use for a 15 sundown I like the thought of being able to stain and clear the wood an how good it will look ! The caricatures of the wood grain with all the detail wood grain has it’s beautiful! They say it’s stronger and lighter then mdf so I’m gonna find out this is a gr8 video and thanks for sharing it nice to have this info I’d like+to see if there would be a major difference with this for lower frequencies like with a subwoofer from 20-250 hz I think I’m gonna do the rubber inside my ported box’s but sealed I just paint them heavy I could tell the difference between painted and not also is I put pillow filler in one seemed like it was a better sound but I’ve only built subwoofer enclosures most sealed but I’m learning ported ones !
Damn son. This guy is a savage. Thanks for this amazing video
Very interesting John
poplar ply is best for speaker building. A secret well worth keeping....
Porous vs. Non-Porous smooth. Wood vs Glass or Glass-like does have an impact on cavity resonance, frequency response. As a simple example, take a high end classical guitar, the type of wood will have an impact on sound, but it is also a matter of volume, geometry and in the case of speaker enclosures the electrical components (drivers and X-over network).
Formica applied with contact cement, as a finishing laminate over MDF or Plywood, in my experience adds a more solid enclosure which holds sound rock solid provided the box is sealed, ported and tuned properly.
This is where blind testing comes into it.
But MDF is great cheap in lots of sizes you want to use and if you don't like the look, you can cover it, as most do. Unless you are going superhigh end and the wood you use is your selling point.
Zu Beginn des diy lautsprecherbaus gab es kein MDF in den frühen 80ern. Spanplatte! Massivholz in jeder Art war verpönt. Wegen der Eigenresonanzen. Multiplex gab es nur für PA. Eine gute Alternative war 2 verschieden dicke Platten mit unterschiedlichen Resonanzen zu verleihen. 19mm +13mm. Heraus kam ein wirklich brauchbares Resultat 👍👍🇩🇪
Would be cool to do measurements of metal cabinets as well.
I remember well in the 70s all British speakers were made with chipboard. Then the BBC started doing tests on cabinets. They concluded that plywood gave a higher frequency resonance but was easily dampened by bitumen panels glued to them. Chipboard had lower resonance but was harder to remove. It was not long before a number of British speaker makers also started using ply with damping panels. Spendor, Rogers etc. These were very good sounding speakers, was it because of the ply or were they just better speakers?
The best results gives a sandwich of glued chipboard inside and MDF outside with veneer. Chipboard absorbs sound better then MDF. But MDF gives stability and robust construction.
What kind of glue between them particle and mdf?
I think the purpose of damping is twofold: First, it helps reduce the amplitude of standing waves and second, it adds to the mechanical resistance as seen by the loudspeaker. Thus, in a sealed enclosure, the lack of damping will necessitate a slightly larger enclosure for a given target Q.
I always use MDF. Only because the last few times I used ply, I ended up with rattles from voids or delamination in the ply.
Voids in the plywood is often used as a reason not to use it. But I've yet to cut into any that had anything inside to rattle, and I've cut through hundreds of sheets of plywood of every grade.
@@IBuildIt I must be very unlucky then. Mind you, to buy good ply in the UK, you have to sell your house to afford it.
Then I suggest next time get proper quality Birch "Void Free" but you have to spend MONEY
No such thing as a free lunch
@@amgineacoustic No shit Batman. If only I had thought about that and commented about that in this very thread?!