How To Combat Speaker Cabinet Resonances

[@generationbehindhifi]

Below are some of the damping materials that I like to use: Peel and stick butyl rubber sound dampening peel (Generic Dynamat): amzn.to/3Nk29nJ Sonic Barrier 3 layer system: amzn.to/3M7TXrb Sonic Barrier foam 1/2": amzn.to/3S4GJzh Polyfill: amzn.to/3Fn9RtR 1/4" MDF sheets to laminate inside of cabinet with: amzn.to/46VoGzG Carpet padding 3/8"-1/2" - Available at any home improvement store Blu-Tack (great for making gaskets and sealing port holes): amzn.to/3CC3DoL Dayton Audio DATS v3: amzn.to/43PBZAu Rockwool Acoustic Stuffing: www.acoustimac.com/roxul-rb6-2in?PMax/Insulation/2023&hsa_acc=4716037441&hsa_cam=17880814997&hsa_grp=&hsa_ad=&hsa_src=x&hsa_tgt=&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gclid=Cj0KCQjwhL6pBhDjARIsAGx8D595-ldQnngjCv6lEevkFWJpPpR4tMOCJ4-jHq2IIPRKGUDxeymsUukaApVnEALw_wcB My videos about upgrading speakers can be found here: kzbin.info/aero/PLg0Xq1LbiZBV3JdrXQtMPgv3Lc6YB6fdr

[@boriken395pr]

Thanks! Well done!

[@NeilBlanchard]

Here's a method I use to find the resonances in speakers - place the two speakers face to face, and wire one of them with the speaker wires inverted i.e. connect the positive wire to the negative binding post, and the negative wire to the positive post. Use an online tone generator to play tones from the bass up to treble (20Hz to ~5kHz). The main output from the drivers will largely be canceled out by playing a mono signal and one speaker being inverted. What you can then hear/feel is the cabinet resonances (and a few other things). If the cabinet "lights up" with vibration in certain areas, you can feel/hear where the weakest points are in the cabinet. I would also *always* add a rib across the inside of the narrow web of the front baffle between the drivers. The movement of the woofer/midrange cone is always going to stress the weakest part of the baffle - which is always the narrowest web. A rib of 3/4" plywood the is an 1"- 1.5" wide, glued on its edge across the width of the front baffle is a minimum. I would look at a strut connecting the new rib to the back baffle next - this adds a lot of stiffness to both the front and back baffles. You can also add ribs to the side panels that overlap with the rib on the front baffle at the corners; and a rib across the back baffle that is parallel with the front rib. You can go all the way and have a strut side to side and front to back, that are glued to each other in the middle - this forms a so-called window brace. The stiffness of all the speaker panels are multiplied by an order of magnitude. And the total reduction of the interior volume of the cabinet is fairly small. Repeat this at a different height(s) in a tower speaker. It is a good idea to have the spacing of the ribs at ~1/3rd or ~2/5ths of a given panel span. This distributes the resonances and their harmonics out. Putting a rib/brace right at the midpoint of a panel will have stronger 2nd harmonic resonances that sum up for the two halves of the panel; if that makes sense? I would advocate either for thin panels added to the cabinet panels (and possibly using silicon rather than glue) - OR - using foam like the carpet pad, or 3-layer damping foam like Parts Express sells on the remaining open panel areas. The foam won't displace the volume of the cabinet, and it will actually lower the tuning somewhat. If you use 1/4" MDF panels with flexible glue/silicon, they will damp the panel *because* they flex a bit, and they won't displace as much volume as thicker panels.

[@generationbehindhifi]

Thanks, Neil! Those are great suggestions!

[@Douglas_Blake_579]

Excellent advice, as always, Neil. You can get away with a bit of extra bracing in the T652s because the box is a bit oversized to begin with. (It should have been about an inch shorter)

[@michaelbelluso]

Well said and thought out. Appreciate not having to reinvent the wheel.

[@Douglas_Blake_579]

The "laminating" process will work but it also significantly reduce the internal volume of the speaker since you are trying to build a stiffer wall. An equally effective result can be gained by "constrained layer damping", aka CLD. (do a search) Basically you are using a thin layer of mdf (1/4") or hardboard (1/8") bonded to the speaker cabinet with a very thin (1/16") layer of silicone rubber. The clear Silicone used for bathtub calking works well. Then as the cabinet flexes it induces stress into the rubber which then, being an elastic material, counters the tendency to vibrate. Just one word of caution about the silicone here... thicker is not better... we are not padding the speaker with silicone we are building a dynamic anti-vibration system. Thinner layers build more tension and counter smaller vibrations. I've used CLD in the the T652s he's demonstrating with and the results were the same or better ... with no significant change in internal dimensions. The carpet underpad is an excellent padding material as well.

[@generationbehindhifi]

Hey Doug! Thanks for the tip. I have never heard of CLD. It sounds interesting. I will have to look into that!

[@gfunkHP]

This sounds awesome, I am inexperienced and researching for woofer box in the hatch back and just for general purpose. Don't mind spending more time on a diy fully enclosed box build and this seems like a really cool upgrade!! Considering working with a 'passive radiator' in the box as well. Great video

[@Douglas_Blake_579]

@@generationbehindhifi Hopefully they'll let me post this ... This is the best demonstration of CLD and how to apply it that I've seen... kzbin.info/www/bejne/e3bLYWSGjZKkb6ssi=WgxP9X_3K2mrdIEi&t=2040 This is a friend of mine doing CLD and bracing in a pair of T652s ... kzbin.info/www/bejne/mXzGfXuDhK9nrassi=eGCm775H_Vsy-rQY I first started using this technique back in the late 1970s when building a pair of "killer" speakers for my own use. I don't know of anyone that was using it before me, but over time it has proven itself to be a very reliable way of damping large panels.

[@bbfoto7248]

Great video. Just note that this process and the materials used should be referred to as "Damping", not "DampENing", which would have to do with moisture issues, not resonance/vibration control. In addition, the fibers from mineral wool/Roxul are also harmful and should also be contained. If you encapsulate the mineral wool within 3 mil thick plastic sheething or "bags" it will still be acoustically effective but will contain or encapsulate the fibers. I have used "Turkey Oven Bags" for this because they are incredibly tough & resilient and will not deteriorate over time. Find them in the cooking goods section in your local supermarket. They come in a small box similar to plastic Zip-Loc bags. Personally, I always choose natural lambswool as my preferred "fiberfill stuffing", which is not harmful to your health and is also one of the best performers in terms of these types of acoustic fiberfill materials.

[@RobertCookcx]

This is a fantastic video. I use the laminate process myself. One point is that if you stage the laminate pieces so they are non-uniform between parallel walls, that is also a benefit as you don't have walls coupling as you would if you simply have a brace. Nice work

[@generationbehindhifi]

Thanks, Robert! I appreciate the additional tips as well. Happy listening!

[@buzzcrushtrendkill]

Two pieces of cabinet material with a constraining layer of urethane between them.

[@n.o.b.s.8458]

Aside from thin damping material, I'd avoid these methods unless you're just interested in tinkering. Adding a significant amount of material to the inside of any enclosure may fix problems in a specific area, but it will cause other problems to pop up as a result. predominantly, it will impact the bass region and change how the woofers perform. enclosure design (when done with any care) involves a careful balance of internal volume, port tuning for that volume, and factoring in the additional volume taken up by anything that's inside of the box. It's possible to directly upgrade the design without creating any negatives, but this would involve a lot of careful management of the exact cubic space of material that you're adding, factoring in the parameters of the drivers, enclosure volume, port volume, etc. At this point you're looking at learning several pieces and some pretty in-depth info about speaker design. I'm not trying to discourage anyone, but if you're trying to do these kinds of upgrades and shoot for a measurable improvement, you may well end up pulling your hair out with frustration when you spend hours making these changes and find only marginal improvements, or worse performance than you started with.

[@EggMCMUFFIN-e4l]

Damping*

[@n.o.b.s.8458]

@@EggMCMUFFIN-e4l fixed! Ha ha thanks.

[@RdandTrk1]

This was an awesome video. Very interesting. You make me want to try DIYing some things, haha.

[@generationbehindhifi]

That's the spirit!

[@gregkempchannel]

Great video. I used these techniques to stiffen up some Sony SS-CS3 which sadly are known for poor cabinet bracing (I knew this when I bought them, but got a deal and figured it would be cool to see if I can improve them). They basically had no bracing below the port and just some bracing up top. I added strips of 3/4" MDF as wide as I could get in there, gluing them in place with Titebond. I then added a some of that Amazon fake dynamat stuff up top and some extra foam stuffing (I'd like to use something better eventually but I had the foam on hand). The cabinets are a lot more quiet and they sound much better now to me (nothing objective, just my ears). If you can get these on sale or second hand and don't mind doing some work these can be good speakers IMO.

[@generationbehindhifi]

Thanks, Greg! It sounds like you did a great job with the SS-CS3 speakers. My favorite part about this hobby is tinkering. I enjoy buying budget subwoofers and making them better. I did it with my Klipsch R10SW and JBL 550P and both turned out pretty well. Some people wonder why I do this, but to me its fun and enjoyable. Plus, I learn a lot by trial and error. I'm glad things worked out for you and keep on tinkering!

[@christopherwilson6825]

For me I used vinyl floor tile first to line inside of my Polk audio 70 series 2 loudspeakers with cement glue . Then I used acoustical foam over top. My,my,my the difference it made . Thanks to Richie from "GR Reesearch" and others that put out videos on this topic. No !! Resonance at all. Simple knock test did the job. Just another part of the hifi journey.

[@generationbehindhifi]

I have heard good things about the floor tiles, but personally haven't tried it yet. Thanks for sharing!

[@christopherwilson6825]

@@generationbehindhifi no problem. I want to try using the dynamat. Pressing it against the enter walls of the loudspeaker or bookshelf speaker . That also seems logical as well to knock down resonances . Just be very careful of crossover touching the metal part of the dampening.

[@Birmingham_racing]

Wish I knew more about this before getting rid of my kef q950s

[@tpop3723]

Dude wtf is wrong with you the q950’s are great speakers.

[@Pete.across.the.street]

I would never do that laminating, adding a brace would be fine. How would you know how much fiber to put in to counter the laminate? I would only do dynamat on the metal parts. Sonic Barrier 3 layer or No rez would be the only things I would use. You are probably better off putting that money towards a better pair of speakers until you get up to ~$2000 range. That's the sweet spot where you can get a good sounding speaker with a decent box. As you move up you start paying for more build quality. If you get a good pair of speakers add the no-rez, upgrade the crossover, then you have a great speaker for cheaper than you could buy. If you start with Dayton audio, there is only so much you can get out of it.. But if you already have the materials sitting around and the speakers, go for it. With that echo in your rooms, your money would be best spent on some room treatment.

[@generationbehindhifi]

Hi Pete, I think you might be missing the point of this exercise. If you really want to learn about speakers and what makes them tick (Total Q, the effects of enclosure size, resonance, etc.), then this kind of tinkering is a must. I understand its not for everyone, but there are some people out there who are like me (people who like to tinker) and don't mind spending few bucks on additional materials to see if it a little sweat equity improves the sound from their budget speakers. Sure, spending more for better speakers is usually the wiser choice, but trying to improve a budget speaker is also fun and entertaining IMO. Maybe it's just me who likes to tinker to see how much performance I can extract from a budget speaker? As for your second question regarding enlarging the perceived volume of the box by stuffing it with damping material, well that can easily be proven by doing an impedance sweep and measuring the resonant frequency of the speaker. We already know a larger enclosure will result in a lower resonant frequency, so all you need to do is run some before and after tests to see if it actually works. If the resonant frequency of the speaker goes down after stuffing the enclosure, then you know it worked. Hope this helps! Thanks for the comment! And hopefully you will do some tinkering on your own one of these days. :)

[@Douglas_Blake_579]

@@generationbehindhifi There are indeed lots of people who love this kind of tinkering. I've been an electronics tech for 40 years and have "tampered" with a lot of stuff. The T652s are great DIY speakers. The drivers are sound. The Box is flimsy but well made and adding a crossover works wonders for them. At one point in the pre-covid days I used to do 1 or 2 pairs with CLD and a crossover every month for friends and friends of friends. Then coupled with one of the nice Class D mini-amps they make an excellent "sound bar killer' system for your TV listening. In some rooms it's even "no sub required", which is even better.

[@generationbehindhifi]

@@Douglas_Blake_579 Hey Doug! The bass from the T652's is quite decent and honestly it surprised me. I only paid $79 for these speakers (open box) and was pretty impressed with the value for money proposition that they provided. I need a new oscilloscope and was wondering if you could recommend one? I want to use this scope for figuring out the average power from amplifiers and I'm currently looking at the Hantek DSO2D15. It's a 150MHz digital scope with a built in function generator. Thoughts? Thanks!

[@Douglas_Blake_579]

@@generationbehindhifi Yep, the T652s are a favorite among people just wanting basic sound and those who like to tinker (or tamper) with things. I've used them myself. For the scope, yes Hantek is a good name. I use a DS5000 on my general test bench and had their "even better" models on my bench at work before retiring. They'll do a good job for you. But one thought if I may ... given that you're doing the YT Creator thing you may want to invest in a USB scope so you can do screen captures for your videos... The higher end Hantek USB modules are really quite good. (LOL Just imagine... a 60 inch scope display!)

[@generationbehindhifi]

@@Douglas_Blake_579 Thanks for the recommendations! Heck ya! A 60"+ scope display does sound pretty sweet.

[@smamas114]

I was just about to ask if i can put rubber inside the box :)) but then i saw the end of the video and it answered my question

[@BostonMike68]

I build multiple layer mass loaded cabinets for my speakers

[@blaze2051]

Thanks!

[@generationbehindhifi]

Wow! Thank you so much! 🙏

[@rupe82]

What exactly does cabinet resonance sound like? I have a pair of active speakers that have an egregious amount of buzz around 270hz and I'm wondering if the speakers are faulty or it's just cabinet resonance..

[@generationbehindhifi]

A ringing sound. This could be a "buzzing", "ringing", or even a rattling sound. If you put your hands on either side of the cabinet and press in, does the "buzz" go away?

[@rupe82]

@@generationbehindhifi It doesn't go away but it reduces it.

[@generationbehindhifi]

@@rupe82 I think you just found your problem area. 🙂

[@rupe82]

@@generationbehindhifi Today I learnt something new! Thanks. At least I know my speakers aren't faulty..

[@ericschulze5641]

Never a need to measure anything, don't buy any test equipment, your going to install bracing and sound deadening anyway, just don't over do it, everything will be fine, & you can't easily undo what you've done, once you do it

[@crossoverchef]

having it on the table like that will surely amplify your knock.

[@JR-ho5qm]

Box Speaker mods are allot of fun! I have also drizzled some hot glue on the stamped steel woofer baskets. Also rounding over the inside of the baffle were the speaker mounts is a nice cheap upgrade 🔈👍🏻. My current speakers are lined with NO-REZ and it really tightened up the base. Cabinet damping definitely helps out. Good video!

[@generationbehindhifi]

Hi JR! Those are some great ideas. I'll definitely keep those in mind. Thanks!

[@RdandTrk1]

Never heard of drizzling hot glue on the stamped woofer baskets before. What is the idea behind that if don’t mind my asking?

[@JR-ho5qm]

@@RdandTrk1 I just figured it could help stop or dampen the ringing that cheap stamped steel baskets are known for. More for very cheap DIY stuff. I have also used automotive spray dampening material, however it is not cheap.

[@generationbehindhifi]

@@JR-ho5qm Yeah, stamped steel baskets are notorious for resonating. I used to put strips of a Dynamat like material on them, but hot glue would be a much cheaper option.

[@Douglas_Blake_579]

@@generationbehindhifi In cases like sealed boxes or transmission lines, where you're working with Poliyfil (pillow stuffing) you can also take some nylon window screen and cover the openings on the basket to prevent the padding from getting against the woofer cones. Bond it in place with hot glue or silicone and you get damping on the basket itself, too.

[@Spierdalajyoutube]

Why not duble wall with sand between?

[@generationbehindhifi]

In theory it sounds like a great idea, but I wouldn't know how to implement that into an already constructed speaker cabinet.

[@Douglas_Blake_579]

Because you would then have to contend with the inner wall vibrating against the sand which would in turn vibrate against the outer wall. It's unlikely to have much effect.

[@dougb5028]

Not the best way to control resonances.

[@davidtennien39]

Adding mdf board changes the volume of the enclosure.

[@generationbehindhifi]

Yes and I mention that in this video.

[@zacktinayoutube]

​@@generationbehindhifiSure Did, Great video Brother 👍

[@jmw611]

Tackle the resonance in that room huh? Lol

[@generationbehindhifi]

I never said I had an anechoic chamber. I think some of the commentors are missing the point of this exercise, which is to tinker and have fun doing so. :)

[@jmw611]

@generationbehindhifi I got it. It was a joke bro.

[@generationbehindhifi]

@@jmw611 lol! Sorry! It's hard to tell sometimes through a computer screen. No worries!