Scrap Pile Builds: Three Affordable Kits

[technodanvan]

As I continue to wait for my subwoofers to be finished (they've been delayed to next Friday, allegedly) I decided to make some sawdust.

Back when I first purchased the kit for Wolf's Zingers (before the tweeter change) I had nabbed several other affordable kits as well - a bookshelf and two pairs of towers (though they aren't very towering). The nice thing about these kits is that I actually have places in mind for them! Since they are all reasonably affordable (the most expensive being around $450 at the time of purchase...though now I see that has gone up in price over the last two years) I decided to go to my well of scrap pieces to see what I could repurpose. Turns out, I could make all of them without having to break down a new sheet of anything.

The bookshelf should be the nicest one, with a design similar to that of my Zingers - 18mm Baltic Birch ply all around except front and back, which will be 3/4"+ bamboo. The cabinets will be painted and the bamboo left bare with a water-based clearcoat. The towers (two separate kits of differing designs) will be constructed with 1/2" MDF all around, with 18mm Baltic Birch on the front. I haven't quite yet decided on the finish for these yet, but they'll probably be painted as well. On the 'nicer' tower I may overlay a piece of 3/4" bamboo plywood on the front where the speaker drivers mount. I don't have enough left to do two whole baffles out of it, but I could split the piece I have remaining.

As far as colors go, I want one set to be an approximation of candy apple red. Another set may be bright yellow. The third could be white or black. All of them would be glossy. Depending on how my subwoofers turn out I'll use the same shop for finishing these. This is all kind of presumptive at this point so changes could occur, but I really don't see veneering as an option for these kits.

What kits are they you say? Well have a look and take a guess!

[JonMarsh]

Ah, I love the smell of sawdust in the spring time!

(of course, I actually love it any time of year!)

Funny, I was looking at kits at Meniscus yesterday just for fun, but the only interesting one (for me) had the link blocked, so I'm guessing he can't offer it at this time for supply chain issues...

I have a big re-org planned for the garage to get things moving, but I need a day where I can push things out on the driveway to facilitate moving stuff around, and the weather just hasn't been cooperating- a very unusual (for here) string of thunderstorms and high winds...

[technodanvan]

Unfortunately I didn't make any further progress last weekend, it was just a bust overall. The way it goes sometimes. I did at least pull all the necessary drivers out of storage so I can measure the diameter and such for cutting holes...maybe this upcoming weekend if the heat isn't too bad.

[technodanvan]

Well, I did a little work last weekend cutting all the necessary holes. Turns out it might not be smart to do all three of these at once as I messed up on several. Fortunately, most were just cut a little small so it was reasonably easy to fix with a small rabbet bit and a flush trim bit. However, one port hole was cut too large (by maybe 1/8"-3/16") and I'm still trying to figure out how I'll fix that. It's an odd size (2.5" ID) so I have to make it myself - no buying a precision port for this project.

Also, I'm unsure if I want to rabbet the drivers for the towers. Given their likely use case I am not concerned about edge effects, and more concerned about aesthetics and how I'll finish them.


I did flush mount the drivers for the bookshelf speakers. The tweeter is a VERY snug fit, so I might have to widen that by a smidge before finishing the bamboo.


Hoping to get back out there this weekend. I think it might be time to start gluing up the rest of the boxes.

[technodanvan]

Well, I have been looking for an excuse to get a 3d printer...I wonder how well that could be routed after insertion for the roundover.

[Scareurpasenger]

If you provide a stl or step file I can print it for you.

[technodanvan]

Thanks for the offer! It is something to consider as I evaluate my options. I could, of course, just make another baffle...but I'd rather not cut down a perfectly good 5x5 sheet of BB for this while they're still in the 'precious' sales category. I have other plans for that already...

[technodanvan]

Well that's some bummer news, Meniscus seems to be shutting its doors. None of the kits shown here are even on the site anymore!

For some good discounts head there quickly, they even have some OEM RAAL tweeters at a good price.

Edit: RIP my wallet. Grabbed some RAAL tweeters and three (not inexpensive) kits. Kits weren't on sale but I figured this is probably the best price they'll be at.

[theSven]

Well that's some bummer news, Meniscus seems to be shutting its doors. None of the kits shown here are even on the site anymore!

For some good discounts head there quickly, they even have some OEM RAAL tweeters at a good price.

Edit: RIP my wallet. Grabbed some RAAL tweeters and three (not inexpensive) kits. Kits weren't on sale but I figured this is probably the best price they'll be at.

Cuss that is a big loss to DIY 😭

[JonMarsh]

Got the email notice from them yesterday, forwarded to Steve. Considered the RAAL tweeter (I still have several) but decided I needed to stay focused....

[technodanvan]

Considered the RAAL tweeter (I still have several) but decided I needed to stay focused....

Focus is good! You'll have to let me know if you do anything with the RAALs, I of course have no idea what I'm going to do with mine, other than add them to the shelf!

Made a little progress over the weekend. First I cut down some PVC for the ports on two of the three kits. I haven't decided if I'll port the third set (Keramiskas) yet. I went ahead and countersunk the drivers for the Overnight Sensations TMM and carved out a bit of the backside as well, then epoxied the ports in place. I think I'll wrap up the OS build before doing much else on the others, it'll be nice just to get them out of the garage to free up some bench space. Just gotta install the crossovers, shove in some stuffing, and glue the baffles in place...maybe all done next weekend.

Oh, as far as mistakes go one thing led to another and...one of the baffles was sort of accidentally epoxied to the floor. Fortunately, I caught it before it COMPLETELY set and it is salvageable.

[theSven]

Oh, as far as mistakes go one thing led to another and...one of the baffles was sort of accidentally epoxied to the floor. Fortunately, I caught it before it COMPLETELY set and it is salvageable. [/FONT][/SIZE]

OMG!!! I could only imagine how it would have gone if you had not caught that and had to figure out how to get that off the floor. The build is coming along and great to see all the photos of the progress.

[technodanvan]

Yeah...even with the floor being painted I'm not certain how well that would have played out. As it is, I've mostly been able to tear off the epoxy by just lightly prying on it with an abused chisel.

Anyone have thoughts on porting the Keramiskas? My understanding is they can make decent bass out of that 5" driver, perhaps even into the upper 30s or so. My thought process was that I'd probably use them with a subwoofer anyway, so the more gradual roll off of a sealed alignment might make integrating them a bit easier.

I might also be looking for an excuse to not bust out the circle cutter again. Maybe.

[theSven]

Yeah...even with the floor being painted I'm not certain how well that would have played out. As it is, I've mostly been able to tear off the epoxy by just lightly prying on it with an abused chisel.

Anyone have thoughts on porting the Keramiskas? My understanding is they can make decent bass out of that 5" driver, perhaps even into the upper 30s or so. My thought process was that I'd probably use them with a subwoofer anyway, so the more gradual roll off of a sealed alignment might make integrating them a bit easier.

I might also be looking for an excuse to not bust out the circle cutter again. Maybe.

I would go sealed if you're going to use a sub with them, keep it simple for now. Worse case you can always make another cabinet with a port. Or even look at 3d printing a cabinet.

[technodanvan]

Well I've been working on the Keramiskas plan a bit since the Overnight Sensations TMM are basically done (minus a finish that has yet to be determined by my significant other). I started modeling the inner core to figure out dimensions and such. Here's what I have so far:

• The inner panels are all 1/4" Baltic Birch plywood. Depth of the speaker has been increased by several inches (around 3, I think) to account for the thicker sidewalls (~1.25" all around)
• The brace/inner roundover for the port would be 3/4" BB or MDF (whatever scraps I have).
• The red ribs would be aluminum stock, adhered to the inner BB with epoxy.
• On the rear there is an additional block of wood surrounding the terminal cutout, this isn't necessary for the port as the port would be inserted (though it is not shown here).
• Surrounding this on all sides except the empty front would be either more 1/4" BB or Hardboard. Probably BB since I'd need to order some anyway.
• Polymer concrete (epoxy granite) would then be poured from the baffle side while the box rests on its back, on a vibration platform to encourage the epoxy to flow to all corners. Care would need to be taken to ensure no overflow remains - this would need to be level in order to attach the baffles (which are 'traditional' 1.25" thick bamboo plywood leftover from my failed Ardent project a few years back).

This looks pretty good from where I'm sitting. I think I'd shorten up some of the ribs a hair and make the terminal block as thin as possible, but otherwise I think it should work. I did think about doing this the opposite way - adhere the baffles first and pour from the rear, but I'm not sure there is a clear advantage to either method.

[technodanvan]

I played around a bit more this morning after thinking on it last night. I brought the outer ribs in by 3/4" to bring them nearer to the center of each panel - in theory the corners should be stronger anyhow, so they need less reinforcement. This also provides more room around the corners to pour the epoxy. I also shortened the ribs by a few inches as they really shouldn't need to go end-to-end. This gives more room for the epoxy to pool at the front and rear. Finally, I thinned the terminal 'block' and expanded the H-frame on the rear to give more room for the epoxy to flow better around the terminals and port.

I think the only thing I'm worried about at this point is whether the epoxy will be too viscous to flow to the hard-to-reach areas. I think I'll need to run a couple experiments getting the right mixture for this. Weight should be interesting, according to Fusion 360 this inner box and frame already weighs 26 pounds - we still need the outer panels, baffle, and polymer concrete (not to mention drivers and crossovers). That seems high to me, but it seemed about dead on for the subs so maybe I'm underestimating the weight of the aluminum.

That reminds me, I need to bust out the crossovers to see how big they are. They'll need to fit through the driver hole (and brace hole) and work within that layout. I may need to adjust the brace to be a square on the bottom to allow fitment.








Edit: Crossovers are pretty good size. I'll need to adjust the brace so at least one can rest on the bottom of the speaker.

[technodanvan]

Here's a few pictures showing where I'm at on the Overnight Sensations. Crossovers are installed and baffles have closed up the boxes. I had to change my plans on the terminals but that worked out, I'll just use plastic cups on these since I have a pair in the parts box gathering dust. Just need to figure out the finishing scheme and do so sanding. My spouse indicates dark green or burgundy could be an appropriate match for the HiVi woofers.

[theSven]

I say go with burgundy, you already have a green pair. Keep adding different colors to have a colorful speaker assortment 😀. Having a spray job done like the last white cabinets you did would look fantastic!

[technodanvan]

That's kind of my thought process as well...except I can't stop thinking dark green would look better! I think we'll hit Home Depot sometime and check out some color swatches so I have something to take with me to the painter.

[technodanvan]

I ran some new models this morning and came up with ~500 in3 of volume for the epoxy - or around 8L per speaker. This model doesn't take into account the aluminum bar (I was lazy) so in reality I'll use less. Model claims a weight of 57 pounds per speaker - not counting port, brace, baffle, speakers, or crossovers. I think that's a worst case estimate, I imagine the finished product may approach that once everything is considered.

I also did some research last night on the type(s) of sand used in epoxy granite, as that's basically all the material is. Something like 80% by weight sand and 20% by weight epoxy. The devil is in the details though - if you have larger sizes of sand you don't get very good packing (imagine those racks of 12" bouncy balls at Target/Wal-Mart - there is a lot of air between them) so you generally want smaller sand mixed in to fill those gaps and maximize density. There is a place in Denmark that will make any mixture you ask for but I'm kind of hoping I can get the same service in the US...and I'm hoping I don't literally have to order a ton of it. I've also been trying to determine if metal sands (or even tiny weights, such as lead shot) could be used in the mixture. I have a feeling that consistency is more important though, and those weights would be too large to be effective.

[Steve Manning]

Hey Danny, I curious, why epoxy? I apologize if the reason has already been given. Something that came to mind was an elastomericroofing sealer would offer a better dampening solution?

[technodanvan]

Hey Steve, this is kind of going back to the 3-D printing thread. I'll link the wiki articles again. This composite material is commonly used for damping of heavy machinery in place of real granite or iron or steel slabs as it generally costs less and is much quicker to form and set. It also doesn't expand or contract at normal operating temperatures. While a viscoelastic product as you suggest could also be effective at damping vibrations, I'm going more for the densest, heaviest substance I should be able to pour and form. Remember I'm only using 1/4" wood for the forms, so most of the strength and stiffness of the walls is coming from the 20mm thick epoxy granite (and the supporting ribs). Since it's self leveling and flows as a liquid I should get minimum porosity (with an appropriate as-yet-to-be-determined mixture) and a near uniform product provided the vibration table I make is sufficient to the task.

One thing to keep in mind is that mixing epoxy is an exothermic process; making large amounts can apparently heat up so much the mixture starts to smoke! I don't know that I'd need to mix THAT much, but it is a reminder this should be done in small batches.

https://en.wikipedia.org/wiki/Epoxy_granite

https://en.wikipedia.org/wiki/Polymer_concrete

https://www.adambender.info/post/201...e-frame-how-to

[technodanvan]

Well, I think I have the Keramiskas Polymer Concrete (PC) design sorted. It actually ended up a hair narrower than Craig's original design, but I don't have the heart to go back and make it bigger. We're talking a few 32nds of an inch here, and given that I was mixing imperial and metric measurements the entire time it's a miracle it was that close. It's fairly deep, but based on the images below I think it still looks reasonably proportional to itself. If I can stick with my current baffle (already made from bamboo) the wood will be a lighter color - I'll finish it with a water-based clearcoat of some variety. Goal is to have a high gloss finish on the rest of the cabinet, but we'll see how reasonable a request that is at a later date.



I think this side profile picture has me convinced I should make some matching stands for these. I should probably make them at the same time, lest I get too excited about the next project to finish them. Maybe I'll get out some napkins and start doodling.

Finally, because I'm a tease, here's a pic of the parts starting to arrive from Meniscus.

[JonMarsh]

I think you're just having too much fun, Danny!

[theSven]

Well, I think I have the Keramiskas Polymer Concrete (PC) design sorted. It actually ended up a hair narrower than Craig's original design, but I don't have the heart to go back and make it bigger. We're talking a few 32nds of an inch here, and given that I was mixing imperial and metric measurements the entire time it's a miracle it was that close. It's fairly deep, but based on the images below I think it still looks reasonably proportional to itself. If I can stick with my current baffle (already made from bamboo) the wood will be a lighter color - I'll finish it with a water-based clearcoat of some variety. Goal is to have a high gloss finish on the rest of the cabinet, but we'll see how reasonable a request that is at a later date.



I think this side profile picture has me convinced I should make some matching stands for these. I should probably make them at the same time, lest I get too excited about the next project to finish them. Maybe I'll get out some napkins and start doodling.

Finally, because I'm a tease, here's a pic of the parts starting to arrive from Meniscus.

OK That's impressive with the amount of stuff you have ordered!!!! I expect to see a lot more build threads on the forum from you Danny. You have turned the hobby into and full on addiction and I will keep enabling you by keeping the forum up and healthy 😂.

[technodanvan]

It's possible that I have a problem.

[theSven]

It's possible that I have a problem.

Not unless you admit it is a problem... Maybe it's just a very passionate appreciation for the DIY community of audio. Trying to get more people interested and posting on the forum. I can say it has been good to see more people logging in since I took over. In the meantime I spend hours trying to fix any image that has a watermark. What I thought could be a simple project turned into a never ending nightmare. I guess I may have problem too with trying to fix all the posts with water marked photos...

[technodanvan]

That certainly is a goal - trying to have something to post here say, every other day or so. It's a challenge since I can only do so much on my projects. It kind of bums me out that a lot of posters at all DIY speaker forums (DIYAudio, PETT, MAC/DIY, etc) tend to be the same people who posted a lot 15-20 years ago when I first started exploring this hobby - it's just the popularity of the sites that have changed. It's actually worse than that, sadly, since several of those very knowledgeable posters have since passed away.

I hope that people aren't intimidated by the hobby. I asked a lot of silly questions when I was new, questions that I think most newbies have before they really grasp just how much there is to speaker design. Questions that, for experienced people, are probably tiresome sometimes. Questions that I've seen some experienced people answer with very technical responses filled with hobby jargon...which might be discouraging to people dipping their toes in the hobby. We need new people interested in order to continue the hobby - we have lost a lot of knowledge recently with the passing of Jeff Bagby and a few others.

I've often thought there should be a glossary for people new to the hobby (and for those of us with a not-so-good memory!). Probably a list of acronyms as well. Something we could develop, maybe?

One of the reasons I prefer to hang out here is we see a fair amount of the development and testing process, especially from Jon. We also see a fair amount of the cabinetry involved which can really be helpful when trying to figure out how to put something together. While both of these things can be found at other forums, a fair amount of posters keep that stuff 'close hold' - meaning they don't reveal the details into decisions, they just reveal the end product. I think this has a place; plenty of DIY'ers don't necessarily care how something is made, just that it exists and they can follow the blueprints to make it. Nothing wrong with that! But, for those of us who are still trying to figure out how everything goes together, it can be beneficial to have the design process recorded somewhere. That's why I try to take pictures and post my process for the physical designs.

[theSven]

That certainly is a goal - trying to have something to post here say, every other day or so. It's a challenge since I can only do so much on my projects. It kind of bums me out that a lot of posters at all DIY speaker forums (DIYAudio, PETT, MAC/DIY, etc) tend to be the same people who posted a lot 15-20 years ago when I first started exploring this hobby - it's just the popularity of the sites that have changed. It's actually worse than that, sadly, since several of those very knowledgeable posters have since passed away.

I hope that people aren't intimidated by the hobby. I asked a lot of silly questions when I was new, questions that I think most newbies have before they really grasp just how much there is to speaker design. Questions that, for experienced people, are probably tiresome sometimes. Questions that I've seen some experienced people answer with very technical responses filled with hobby jargon...which might be discouraging to people dipping their toes in the hobby. We need new people interested in order to continue the hobby - we have lost a lot of knowledge recently with the passing of Jeff Bagby and a few others.

I've often thought there should be a glossary for people new to the hobby (and for those of us with a not-so-good memory!). Probably a list of acronyms as well. Something we could develop, maybe?

One of the reasons I prefer to hang out here is we see a fair amount of the development and testing process, especially from Jon. We also see a fair amount of the cabinetry involved which can really be helpful when trying to figure out how to put something together. While both of these things can be found at other forums, a fair amount of posters keep that stuff 'close hold' - meaning they don't reveal the details into decisions, they just reveal the end product. I think this has a place; plenty of DIY'ers don't necessarily care how something is made, just that it exists and they can follow the blueprints to make it. Nothing wrong with that! But, for those of us who are still trying to figure out how everything goes together, it can be beneficial to have the design process recorded somewhere. That's why I try to take pictures and post my process for the physical designs.

We could start an article page that lists terminology. Reet has been creating articles to share as well and I could set you up with access to write too. I could definitely pitch in with editing and looking up terms. The one thing I find amazing is when I go to look something up that I hear it's most likely been discussed on this site and the search finds it. Head scratch time of how did I miss that 8 years ago when they were discussing LoL.

It was a loss with Jeff B and the others passing away! It's depressing to see Meniscus close their doors. With all the traveling I do I try to bring new people to the site that have an interest, but many have not signed up. They were just really interested and either troll without an account or were nice to listen and that was enough. None the less the site is running stable, content is being updated to fix old image links, and people are coming back. I'm happy the site is alive and the data is there for the community to have.

[technodanvan]

Sure, set me up sometime. I kind of imagine this as something that we just slowly add to and not something with a lot of upfront work. It's good the search works well here!

[technodanvan]

Well, I spent some time in the garage today since I started work early (and therefore finished early). Turns out I was unproductive, the heat is coming to the Vegas Valley! Cut a few braces for the Speedsters before calling it quits. Hit Home Depot for some 1/4" MDF for the Keramiskas - I decided I didn't want to pay for shipping one sheet of 1/4" Baltic Birch so I'm going the cheap route. The aluminum came in and it looks really nice. It'll be a shame to cover it up but so be it. It's far too smooth though, I'll need to roughen it up to ensure the epoxy sticks to it.

Also did a little pre-research on a glossary of sorts. Looks like someone had a similar idea at the DIYAudio Forum some time ago...but it's definitely not complete.

https://www.diyaudio.com/community/threads/glossary.171098/

Another from Crutchfield, also incomplete but potentially a good starting point.

https://www.crutchfield.com/learn/car-speakers-glossary.html

I also have several of the usual books in this field I can pull from as well, but I want to be sure the descriptions are more user friendly.


Just crapshooting now (and I don't know why I'm doing it in this thread) but I think these would also be valuable additions:

How to interpret a frequency response graph (with examples of bad behavior and good behavior)
How to interpret an impedance graph (with examples of bad behavior and good behavior)
General characteristics to look for in a tweeter, mid, woofer, and subwoofer (i.e. which parameters are generally most important for these applications?)
And while we're in wishful thinking mode, maybe some videos on how to use VituixCAD (and maybe other popular free and/or inexpensive software)

[JonMarsh]

It's possible that I have a problem.

Time will tell...

[JonMarsh]

Not to go too far off the topic, but regarding your picture, one of ET's buddies noted the NAD gear in the background and had a simple comment:

[technodanvan]

Yeah, I'd be lying if I said I wasn't running out of space to put these things. Between speaker components and LEGO (another hobby of mine), most shelf space in my office and storage shed has been taken. In front of the stereo seemed like an ideal spot at the time.

[technodanvan]

I tackled the messed up port through hole on one of the Speedsters TMM baffles this afternoon. The problem was I cut slightly too large a hole for the port (2.5" ID). Out of the various options I decided to chop off the end and just glue another piece to the end of the baffle. I'm planning on having these painted anyway so I'm not too concerned about it.


Of course, you might note in my haste that the through hole on this particular piece of wood was not particularly large...so mistakes were made, more wood found, and now we should be good to go.

Kylo will definitely approve of the color scheme for the Speedsters. Unless plans change they should be black. Very black.

[technodanvan]

Got some work done this morning before it got too hot outside. First I started gluing up the second Speedster tower.


I cut out all the interior parts for the Keramiskas. Such a small stack when it's only 1/4" wood!


I also cut out the interior brace that will serve as an interior port flare, cut the ports out, and glued them up with two part adhesive.


Finally, I started gluing up the interior bits for the Keramiskas. Since the wood is so thin I'm going to take it slow, I'm concerned about permanently bowing these panels if I clamp too hard. Hoping to go back out sometime this afternoon to glue up a few more panels. I'm kind of thinking if I do this again I might adhere the aluminum to the panels first, then assemble them...but that would only add strength in one direction so maybe it wouldn't be a benefit.

I was going to start cutting the 2020 T-slot but discovered I don't have any metal bits for my jigsaw. So I guess there's no rush on assembling these right now.

[technodanvan]

I got up early this morning to do a little work, unfortunately it was mostly gluing so once that was done there wasn't much else for me to do but wait. Maybe I'll go out this afternoon...but given the expected temperature...



...maybe not.

I finished the interior flare on the ports with a 3/4" roundover that ended up cutting into the plastic a bit. No matter, the epoxy held.


Once that was done, I mocked up the interior of the cabinets with the crossovers. Looks like I have enough room for some options, but I'll stick with the below plan (mostly).


I created a couple of wooden guides to ensure placement of the port was correct. I would like to be within 1/16" of where I modeled it since it needs to go through a sheet of 1/4" plywood, through 20mm of concrete, then end ~3/8" into a chunk of 3/4" bamboo. Should be interesting to see how this turns out.


Finally, I glued some 1" risers for the woofer crossover to the bottom of the cabinet. The intent will be to install 3/4" mass loaded foam beneath them, then use Velcro to attach the crossover boards to the risers.

[theSven]

Exciting to read this build progressing. I've got the heat with humidity over here in VA. Hopefully you're not getting much smoke out that way either, it's been pretty wild here with how much smoke was visible. It's been clearing up since Thursday. Looking forward to seeing the concrete portion build of this happening.

[technodanvan]

I'm kind of stoked for this build, if only because it's something a little different! Epoxy has been ordered and I think I'll just grab a bag of play sand to experiment. I really can't find much research on mixtures of this stuff, at least the sort of material I want to make. I 'think' the best density would come from a mix of coarse play sand and some that has been meshed to a finer grain. For the purposes of this project though, I'm not sure it'll matter. We'll see how the test sample works out. The epoxy is suppose to arrive today so I suppose I should plan a trip to HD this afternoon...

No smoke here until the next California fire, and very little humidity. I'll take it!

[technodanvan]

Here we go again, making mistakes! I discovered that I did some incorrect math after I made the first piece for the back of the speaker, just a 1/4" piece of baltic birch plywood. I noted that the port didn't look like it extended very far, and I was right. It doesn't even extend past the aluminum layer, much less 3/8" into the next piece! So I sat down to think about how that might work and ultimately decided that I won't put the aluminum forms on the back. That bums me out a little, but I found a nice scrap piece of bamboo that will serve the purpose.


First I used a new 2 3/8" Forstner bit (Amana via Amazon) to push a hole through both ends of the scrap. Then I chopped them down to size with the tablesaw.


Test fit...

Getting ready to make another hole...


Second mistake, I got yet another new woofer! Her name is Freya, she is a 12 week old Great Pyrenees. Her arrival put a halt to my work for the rest of the day.

[JonMarsh]

Ay, another Forstner bit fan!

[theSven]

This is creative cabinetry 101, and a good save with the bamboo!

[technodanvan]

I'm not sure it's a save...but I think it'll work! Might have a gap in the port that I'll need to fill in later, but at least there should be no epoxy intrusion. I'm currently at a standstill as I await a few packages from Amazon and Parts Express, but I think they'll arrive before the weekend so I ought to be able to make some progress then. Jotting things down here so maybe I get the order of operations right this weekend:

1. Cut foam to size and install in box where possible. Leave unadhered joints somewhat bare so sealant can be applied later.
2. Install Velcro in boxes and on crossovers, be sure to staple it down in the box.
3. Glue box halves together.
4. While glue is drying:
   1. Build vibration table
   2. Cut down 2020 aluminum - need 20 ~12" pieces (use five 4' rods)
   3. Sand and adhere back to other Speedster
   4. Apply interior sealant to first Speedster
   5. Cut rabbets for speedster baffles
      1. Install ports once baffles are ready
   6. Cut and fit foam for back pieces to the Keramiskas, cut out terminal hole
5. Apply interior sealant and remaining foam pieces
6. Use table router to clean up all joints
7. Rough sand whole box
8. Rough sand 2020 aluminum
9. Mark sides for placement of 2020 aluminum
10. Epoxy aluminum to one side at a time, clamp well.
11. Glue 1/4" back piece to each box. Consider gluing the 3/4" bamboo spacer simultaneously
    1. Clean up edges with table router

In the meantime, when I'm not playing with the puppy, I started sorting through some of my new parts - including the crossovers. I snapped a pic of the below because I like how neat everything looks. I'm going to miss Meniscus for their crossover work...may have to bug Steve Manning about making them for me in the future! Or I 'guess' I could practice and become better at layouts...

[technodanvan]

I've been researching epoxy granite a bit more today, both scientific papers (those few I could find) and more traditional internet searches (various forums and Youtube). This video was interesting, and has me reconsidering the sand + smaller particles. While strength is generally a nonissue, density is what I'm after for this project. The correlation of increased strength to increased density cannot be ignored.

https://www.youtube.com/watch?v=gjw5juGG1g8

I think I'm going to order some 180 grit aluminum oxide blasting powder as my "smaller particles". It's much more cost effective to get 50 pounds of it....so...maybe I'll be doing this on another set of speakers or two if I like the result. The only thing to figure out now is what ratio of sand to powder, then determine the appropriate amount of epoxy. The guy in the video used 67% sand to 33% powder, then used around 13-14% by weight of epoxy. I think I'd prefer to have a little more epoxy to ensure wetting of all particles, and had previously seen 20% used with sand. I have some silicone granola bar forms in my cart...I was thinking about making some small batches of various mixes to see how they look (in terms of porosity) and calculate density. I'm waffling on this because Aluminum Oxide is about twice as dense as your average sand...so 100% powder should, in theory, yield the best density. This conceptually makes sense. But I need to find a happy medium between sand ($6/50 pounds) and powder ($140/50 pounds).

There is probably some sort of cost versus density chart that would show this. I could calculate theoretical maximum density without measuring it and come up with a dollar/density value...just thinking out loud here.

This is all totally opposed to augerpro's findings of course, I'll save that for a larger project!

Edit: I did it! With some convoluted logic and math later...I get something I'm calling an improvement ratio. Basically, this is the cost vs density of n+1 (where n is the % aluminum oxide) divided by cost vs density of n. You'll see we get diminishing returns...curiously starting right around where the guy in the video was using, something like 30-40%.

[theSven]

Have you looked at silica powder to mix with the resin? That is pretty dense and cheap too. I used this a fair bit in the car stereo days to build custom fiberglass subwoofer enclosures. After you had your first layer of fiber laid with resin you would thicken the enclosure with the resin / silica mix and it would make the enclosure super rigid.

[technodanvan]

That really interesting, I had actually been researching that as well, my final undergrad project partially involved silica. In this case, the density is much closer to that of sand than it is to aluminum oxide. However, it's like 1/3-1/4 the price of aluminum oxide...but what I could find wasn't quite as fine. I don't know that would make a major difference. I do think it would absolutely work!

[JonMarsh]

This is all totally opposed to augerpro's findings of course, I'll save that for a larger project!

Let a hundred flowers bloom; let a hundred schools of thought contend.

Mao had used this to signal what he had wanted from the intellectuals of the country, for different and competing ideologies to voice their opinions about the issues of the day.

Now, I'm not a fan of Mao, but the idea holds water in many circumstances, particularly attempting DIY innovations in cabinet design. We probably all have our individual experiences and ideas that contribute to a different concept for directions to explore- I think that is good. The more, the better.

[theSven]

That really interesting, I had actually been researching that as well, my final undergrad project partially involved silica. In this case, the density is much closer to that of sand than it is to aluminum oxide. However, it's like 1/3-1/4 the price of aluminum oxide...but what I could find wasn't quite as fine. I don't know that would make a major difference. I do think it would absolutely work!

Does it need to be fine? When I would mix it, I used a mixer rod on the end of a drill like one would do for mixing tile mud to lay tile. The texture was like pudding and very easy to work with. Just pay attention to how much hardner you mixed in that will determine how fast you must go before it sets. I also recommend wearing a disposable jump suit. That stuff is nasty to get off your skin and you should be completely covered and have a respirator to work with.

[technodanvan]

Now, I'm not a fan of Mao, but the idea holds water in many circumstances, particularly attempting DIY innovations in cabinet design. We probably all have our individual experiences and ideas that contribute to a different concept for directions to explore- I think that is good. The more, the better.

I just wish I had a way to show how this method compares to other materials whether that be a mechanical device or a mathematical model. I suppose one way to do that would be to construct a 'normal' cabinet and an augerpro cabinet, then measure frequency response. Better would be to acquire a laser doppler vibrometer and measure panel resonances. It'd be easier to mock up individual panels for this purpose, I think. That might be out of my price range, but something like the below could work, maybe. At least it has a range to 15kHz, unlike some physical meters.

https://www.amazon.com/AMTAST-Vibrometer-Acceleration-Displacement-Measurement/dp/B0863PHL8K/

Does it need to be fine? When I would mix it, I used a mixer rod on the end of a drill like one would do for mixing tile mud to lay tile. The texture was like pudding and very easy to work with. Just pay attention to how much hardner you mixed in that will determine how fast you must go before it sets. I also recommend wearing a disposable jump suit. That stuff is nasty to get off your skin and you should be completely covered and have a respirator to work with.

I really don't know just how fine it would need to be, honestly. I'm a little concerned about turning this into a putty because it wouldn't flow well and would be harder to pour. I think I'm still going to make some molds to try out a few things. I don't think a suit would be required for aluminum oxide, but gloves and a respirator are probably recommended when dealing with any metal/ceramic powder.

I purchased a new mixer rod for this project as my other one is capped by plastic fins - I didn't think they would do well in this substance. I got a laugh yesterday when it arrived, it's enormous! I did not look at the size when ordering. Should be great for a 5 gallon bucket though!

https://www.amazon.com/dp/B074PC786L

[augerpro]

This is all totally opposed to augerpro's findings of course, I'll save that for a larger project!

Not at odds with my testing at all! Brute-forcing the issue with serious mass is probably a quite effective method. I only started testing to 1) quantify the changes in mass/materials, 2) find a cost-effective sweet spot that was easy to implement. Some of these brute-force methods seem a bit extreme to me, and not many DIYers do it for that reason. Not to mention cost and just having to move 200lb speakers around. I liked CLD because it followed the "work smarter, not harder" ethos. I mean just look at the results from two 1/4" MDF sheets joined with Weicon versus the 3/4" plywood and MDF. One could join the two methods of course, although I would want to quantify the benefits first because I think there is definitely a point of diminishing returns.

I read your other thread, and I'll post some random replies here to your questions. I think a box of 12 Weicon should be quite enough for two floorstanders, even if you triple the layers as you thought about doing. I have a 3D-printed trowel .stl on my website that can help you get a consistent 1/32" layer.

Building box-within-a-box is how I started my testing, but I tell you it's a PITA and easier to trap air bubbles. Now I like to roughcut the panels, glue them with Weicon, and then cut to final size. This way you can also use the advantage of 1/4" wood bending a bit to "roll" it onto the thicker board, to prevent air being trapped. I didn't see any disadvantage in my testing when I switched to this, even though the isolation of box-within-a-box seems to our minds more ideal.

I'll quibble a bit with Xandresen that you must use microspheres. The results of my testing show that you get big improvement without doing that. And where else in industries that use CLD is that a requirement? Nowhere that I can see. But it was an interesting idea of Geddes, and of course I have a box of glass microspheres that I had intended to test! But I haven't yet. It may very well be better than just the Weicon, but that is not the same as saying the Weicon does nothing.

Also the aluminum-backed butyl sheets certainly work, look at the results I've measured. But I've never done the MLV and don't really intend to since it is not CLD. The aluminum is what provides the CLD damping. Without it, it's just a little mass added to the panel.

It would be great to see someone use my testing method to continue nailing down methods I didn't fully explore. Like the concrete you mentioned. If you want the details let me know, I'd be happy to share and start getting more data and validation of methods. For example, while I did measure both 1/2" and 3/4" materials to get some idea of mass/stiffness changes, I never doubled up 1/2" or 3/4" to test the brute force approach. Mostly because the CLD results were so promising. But I would still like to know if there is a sweet spot there. Then perhaps join the two methods.