Scrap Pile Builds: Three Affordable Kits

[technodanvan]

I made a little progress yesterday. First got some foam installed. It's not shown, but I ended up using a staple gun as well. I was a bit worried it would penetrate the 1/4" MDF, and in some cases it did, but only barely so.


Next up was placing the crossovers with Velcro. I had hoped I would be able to remove the crossovers from the Velcro and install them later, but once detached the Velcro barely seems to hold. So I decided we'll just close everything up starting now.


I wired up the crossovers and went the extra mile to solder them this time. On the Overnight Sensations I just used terminals, then placed a dab of ht glue on them to keep them from moving. I wish I had soldered them now but whatever, they should be okay.

Once wired up I glued the speaker halves together.



So here they are at the end of the day, just waiting for the glue to fully set. They're already pretty beefy, despite the 1/4" MDF. You might note I also cut out the terminal hole in the bamboo at some point yesterday as well, though I don't have a picture of it.

[technodanvan]

So today I started work on the 2020 aluminum. I received a few jigsaw blades for metal in the mail recently and was anxious to try them out. The first couple cuts went okay, but I probably should have been using some cutting fluid to keep things cooler - one of the blades warped. Managed to only use two to do all 20 pieces though.



I cleaned up the edges a bit with the sander - those later cuts were pretty rough. Likewise, I cleaned up the glue, routed the edges, and rough sanded the MDF on the speaker boxes. Then I used some JB Weld epoxy to glue the first six aluminum rods to the speakers.


I'm starting to get a bit of concern for the epoxy pour from this experience. Drips from the JB Weld appear to have penetrated the MDF slightly, and I'm a bit worried that with a lot more epoxy it could completely penetrate it. I'm also a bit worried about this individual glue-up - the directions state the epoxy should cure within an hour, probably faster in my environment. Those drips sure as heck haven't cured. That said, I'm wondering if only one part of the mix was dripping before it hit the nozzle. In any case, I'm going to let this set overnight before gluing up the next set. I was hoping to get them all done today, but no matter.

As it turned out, I was busy with puppy stuff anyway. I ran a few errands and bought a baby/pet gate to keep the pup from going up the stairs. Then I made a spacer between the gate and the wall with a cat passage built in. It turned out okay, but of course the cats have gotten around it in every way but going through the thing. Whatever, jerks.


Finally, my shipment of epoxy arrived right as I was wrapping up in the garage and...it seemed something from this one leaked as well...I'm starting to think the 105 Jon uses might be in my future if only because it appears to come in a metal container!

[technodanvan]

Well I decided to check the epoxy one last time and I convinced myself those drips were just one part, the actual mixed epoxy is very well set. So I went ahead and flipped over the boxes and glued on the other side. May still try to do one more side tonight if I have the energy.

[technodanvan]

Took a short break from work today to epoxy the last few aluminum ribs to the boxes. This process went pretty well overall, though using the small double tubes of JB Weld was probably about the least cost-effective way of doing it since I wasted at least a full tube. Oh well.


I also discovered that at least one box is out of square, as xandresen predicted for a CLD-style enclosure made of 1/4" material. It's not bad enough that I'll try to do something about it, maybe 1/32", but it is bad enough I may use three feet for each speaker when wrapping these up. Of course, I don't know how I'll do that since you can't easily drill a hole in polymer concrete. Maybe more epoxy, I guess. I kind of wish I had planned on using 1/2" baltic birch on the exterior of these, or at least on the bottom so I could use brass inserts, but the baffle size is what it is, and a quick check of fitment suggests even using 1/4" material will be close. My CAD model must have been reasonably accurate on this, at least!

I'm hoping to get out over lunch for a few minutes and insert some denim around the port then close up the back with a 1/4" sheet of baltic birch.

Edit: Lunch has come and gone, but I managed to grab about 10 minutes of it for myself.

[technodanvan]

Finally, my shipment of epoxy arrived right as I was wrapping up in the garage and...it seemed something from this one leaked as well...I'm starting to think the 105 Jon uses might be in my future if only because it appears to come in a metal container!

So uh...about this shipment. The box was sitting in open sunlight for maybe 5-10 minutes and I happened to look over and see it smoking! It is now in the shade...and an email sent to the manufacturer. I don't know if I want to use this stuff; they'll need to be pretty convincing at this point.

[technodanvan]

Before work this morning I did a few things, culminating in sealing up the exterior of the interior boxes. I want to ensure there are no gaps in the seams where epoxy could intrude. I think this is the last step before adding the exterior panels, which I have yet to cut. Still waffling on whether I should use the MDF I have or drop some money on a 1/4" sheet of BB. It'd have to be delivered, which is yet another expense.



Fortunately (or unfortunately) there is really no rush. I'm still unsure if I want to use the epoxy I have, but I might break out a bottle this weekend and make a few test samples. Not all parts for my vibration table have arrived either, so that's annoying (a week late on Amazon, how often does that happen). And finally, the forecast means I probably shouldn't be pouring a lot of epoxy anyway, though I think the small test forms should be fine.




Edit: I also wanted to point out the 1/4" MDF now appears to 'pass' the knock test - the aluminum ribs have significantly stiffened the enclosure, despite only being applied in one direction. This kind of makes me want to design a speaker with only external hardwood bracing elements that are both decorative and functional.

[technodanvan]

Last night I started gluing up the exterior panels. I cut them to exact size on the height of the speaker and oversize on the depth and width, to be brought down to spec using a router later (maybe today). I set up the previous boxes I was going to use for the Keramiskas as a stop, applied more JB Weld epoxy, and placed the sides on the ribs. Looks pretty good considering I was rushing a little bit.

[technodanvan]

Well, I'm not sure I'd recommend doing this with 1/4" MDF. I'm pretty sure at least one of the project panels was slightly curved and I'm paying the price now. I think it's just too flimsy to guarantee 90 degree corners all around, and I'm quite convinced my own project is a bit on the curved side now. Granted, that could be a feature if you plan for it. If I do this again - and I might need to based on all the aluminum and aluminum oxide I will have once this project is complete - I think I'll use 1/4" baltic birch at an absolute minimum. It would be better to use 3/8" or 1/2" to ensure some stability, if you can afford to have VERY thick sidewalls. Maybe used in key places would be good to limit how deep these speakers would need to be to compensate.

Anyway.

I cut down the top and bottom pieces and installed them this morning. I had to think a bit about how to glue both the sides and the ribs to these pieces without having the glue run and decided to use a thick glue I had on hand to do so.


This stuff is pretty great, it sticks to vertical surfaces without a problem.


Once that was figured out it went pretty fast.

[technodanvan]

Minor update.

As the heat swelters this week (and probably for the next month) I've taken a slight break from the Keramiskas project. As of today I now have everything I need to build a vibration table, I'm just missing the time and motivation this week. Hoping I can get to it this weekend, and maybe put a small mix together for some trial bars. Waiting is okay, the sand I purchased was a might bit damp so I've been letting that dry out as much as possible. Perfect weather for it this time of year, so that's good.

The cabinets are ready to fill. I glued the backs on and evened up all edges with the table router...may have burned up the motor though, it released some smoke and some disturbing noise on the last cut. Need to find out what that is all about. In any case, they're just sitting on my bench, ready to go. I think I'll tape up all the exterior edges with painters tape before I pour, just in case.

I made another order on Meniscus. I just couldn't pass up the opportunity for a few things remaining there, even though one of them I'll need to buy full price elsewhere. I missed out on a couple other things I wanted but that's okay. Full list of drivers below, though I also grabbed a bunch of wool and damping stuff too.

2x AudioPur PT2522C-4 + Faceplates (shallow closed back)
2x AudioPur PT2522-4 + Faceplates (open back)
2x AudioPur PT6825-8 + Faceplates
2x SB Acoustics SB12CACS25-8
1x SB Acoustics SB29BNC-C000-4 (Beryllium!)
2x Wavecor WF182BD-09
2x Wavecor WF223BD01 (Recently used in DaveFred's InDIYana build)
2x Wavecor TW030WA02
2x Wavecor TW13WA01

[JonMarsh]

Took a short break from work today to epoxy the last few aluminum ribs to the boxes. This process went pretty well overall, though using the small double tubes of JB Weld was probably about the least cost-effective way of doing it since I wasted at least a full tube. Oh well.


I also discovered that at least one box is out of square, as xandresen predicted for a CLD-style enclosure made of 1/4" material. It's not bad enough that I'll try to do something about it, maybe 1/32", but it is bad enough I may use three feet for each speaker when wrapping these up. Of course, I don't know how I'll do that since you can't easily drill a hole in polymer concrete. Maybe more epoxy, I guess. I kind of wish I had planned on using 1/2" baltic birch on the exterior of these, or at least on the bottom so I could use brass inserts, but the baffle size is what it is, and a quick check of fitment suggests even using 1/4" material will be close. My CAD model must have been reasonably accurate on this, at least!

I'm hoping to get out over lunch for a few minutes and insert some denim around the port then close up the back with a 1/4" sheet of baltic birch.

Edit: Lunch has come and gone, but I managed to grab about 10 minutes of it for myself.

You're making some interesting progress... I use the small tubes with the built in mixer/meter function for special small scale jobs, and the big tubes from HD or Amazon that you have to mix manually- they're more of a PITA, but seems more cost effective.

Needless to say, we're early awaiting the results of your experiment!

[technodanvan]

I really like the JB Weld with the mixing tube, it makes things so much faster. But you're right, the manual mix style would have yielded a lot more epoxy per dollar. Maybe I'll try that next time.

[technodanvan]

We have epoxy! I decided to use the mysterious smoking epoxy so we'll see if my house burns down. Unfortunately my mix was not exact; I had planned on doing a couple different mixes with varying amounts of epoxy while keeping a 67% sand / 33% aluminum oxide dust mixture static. I just assumed my scale could handle increments small enough for my mixture. Alas, it did not (0.05 kg is the smallest increment), though it should be fine for the actual pours since they'll be significantly larger. So what I ended up with was probably a 67%/33% mixture of solids with somewhere between a 10-20% mixture of liquid epoxy. I think it'll be fairly forgiving though, given my application and how the sample pours went.


The dust and sand mixed up okay, I was just using a cheap tongue depressor which was pretty wimpy. I'll use something much more solid for the real mix.



Said tongue depressor snapped when I added the epoxy, but only after I had mixed it up pretty well. For the real mix I'll wait and mix Part A first, then Part B once that is all mixed up. Should give me a bit longer work time.


Pouring went well, it definitely still had liquid properties despite all the sand and dust...at least at first. Turns out I did not mix it as well as I thought and it was significantly thicker at the bottom.


However, I think that's a good thing. Even the denser stuff levels out (the sample on the right side) when I tapped the scale a few times. The other three I poured at different thicknesses just to see how strong it'll be. Again, not a big deal for my application, but I'm curious. For actual mixing in a 5 gallon drum I'll use a drill and a big honking stirrer, so I'm more confident about a uniform pour compared to my hand mixed tongue depressor situation.


Edit: I decided to go back out to the garage for a few minutes and poured a couple forms of pure epoxy for comparison.

[technodanvan]

I checked on these today and am pleased with the results so far. They aren't 'quite' set all the way - this is most obvious on the pure epoxy brick as they are quite flexible, but otherwise solid. The polymer concrete is much stiffer, though I can slightly bend the thinnest sample when applying most of my strength. Pretty cool stuff, though it did not achieve the density I wanted...probably because I neglected to include the displacement of solid material by the epoxy. Best I saw was 1.34 g/cm3, a little less than the density of sand by itself.

[augerpro]

So where is this polymer concrete idea from? I like it. Tell me more!

[technodanvan]

So where is this polymer concrete idea from? I like it. Tell me more!

Well, the idea originally started when theSven made the 3D Printed Speaker Cabinet, Can we do better? thread. More specifically Post #15 by Steve Manning got me thinking. The video shown described an aluminum interior enclosure with a fiberglass exterior, with some sort of substance injected between those layers that adds over 100 pounds to the cabinet. I had originally proposed earlier in the thread using lead shot encased in epoxy, or some other combination of materials, so I started doing a little research and quickly came across polymer concrete (a.k.a. epoxy granite) a composite material that is basically a mixture of sand, sometimes gravel, and epoxy. DIY machinists have used this stuff for years to add damping to heavy equipment, like to a big lathe. They pour it into the hollow bases of less expensive equipment to add mass and damping (the expensive equipment might come with a solid machined iron base instead). Some also use it for creating perfectly level surfaces for other equipment in place of buying a chunk of granite.

I should point out this idea is not new. I did find at least one post at the DIYAudio forums asking about making an entire cabinet out of this stuff, which I think would be hard to implement but is otherwise a good idea. However, I was kind of stuck on how Rockport Technologies injected a material between two layers. I'm guessing what they have is a variant of polymer concrete, as whatever they use is reasonably heavy and must not expand or contract while setting - something that makes epoxy look like a good substrate. Note this would also work with 3D printed shells too.

Since my schooling was in materials engineering I was intrigued by the concept and wanted to try it out, so I made a proposal for a speaker cabinet. Since I had already committed to completing my set of Keramiskas I decided they would make a good test subject. They are quite deep now due to the extra thick walls (3/4" vs over 1 1/4"), but otherwise share the same dimensions as the original design. Something I had proposed but decided not to do was make a polymer concrete-filled baffle. This was mostly because I already had baffles made that I didn't want to waste. I also proposed to make ribs in the cabinet, much like Rockport Technologies integrated into their aluminum subcabinet. For fun, I sources some 2020 extruded aluminum T-slot to use for this. Why? I don't know, but it was fun and reasonably inexpensive ($50 for both speakers combined).

So, that's pretty much where we're at. The cabinets are ready with the exception of taping them up, and I just need to build a small table for a concrete vibrator and pick a day to pour. Ideally one not so hot, but we'll make do.

A few photos of one of the bricks I made. This one shows why it's commonly called epoxy granite. This is a very hard substance, much like a granite countertop. You'd need a diamond drill bit to penetrate it.


You can tell there is a layer of mostly just epoxy on top. One thing I had assumed but didn't know for sure was whether the epoxy would wick up the sides a bit. They did, but that should not be an issue later. I'd like to avoid the layer of epoxy on top on the real pour if possible, I assume all I can do is keep testing the mixture so I don't have excess epoxy after the mix. I think I was closer to 20% on this run, so may 15% should be my next goal.


A better shot of the side.

[Steve Manning]

Danny, this video shows how they fill the cavity between the speaker layers. https://www.youtube.com/watch?v=wZijzINOtCU

[JonMarsh]

Well, the idea originally started when theSven made the 3D Printed Speaker Cabinet, Can we do better? thread. More specifically Post #15 by Steve Manning got me thinking. The video shown described an aluminum interior enclosure with a fiberglass exterior, with some sort of substance injected between those layers that adds over 100 pounds to the cabinet. I had originally proposed earlier in the thread using lead shot encased in epoxy, or some other combination of materials, so I started doing a little research and quickly came across polymer concrete (a.k.a. epoxy granite) a composite material that is basically a mixture of sand, sometimes gravel, and epoxy. DIY machinists have used this stuff for years to add damping to heavy equipment, like to a big lathe. They pour it into the hollow bases of less expensive equipment to add mass and damping (the expensive equipment might come with a solid machined iron base instead). Some also use it for creating perfectly level surfaces for other equipment in place of buying a chunk of granite.

I should point out this idea is not new. I did find at least one post at the DIYAudio forums asking about making an entire cabinet out of this stuff, which I think would be hard to implement but is otherwise a good idea. However, I was kind of stuck on how Rockport Technologies injected a material between two layers. I'm guessing what they have is a variant of polymer concrete, as whatever they use is reasonably heavy and must not expand or contract while setting - something that makes epoxy look like a good substrate. Note this would also work with 3D printed shells too.

Since my schooling was in materials engineering I was intrigued by the concept and wanted to try it out, so I made a proposal for a speaker cabinet. Since I had already committed to completing my set of Keramiskas I decided they would make a good test subject. They are quite deep now due to the extra thick walls (3/4" vs over 1 1/4"), but otherwise share the same dimensions as the original design. Something I had proposed but decided not to do was make a polymer concrete-filled baffle. This was mostly because I already had baffles made that I didn't want to waste. I also proposed to make ribs in the cabinet, much like Rockport Technologies integrated into their aluminum subcabinet. For fun, I sources some 2020 extruded aluminum T-slot to use for this. Why? I don't know, but it was fun and reasonably inexpensive ($50 for both speakers combined).

So, that's pretty much where we're at. The cabinets are ready with the exception of taping them up, and I just need to build a small table for a concrete vibrator and pick a day to pour. Ideally one not so hot, but we'll make do.

A few photos of one of the bricks I made. This one shows why it's commonly called epoxy granite. This is a very hard substance, much like a granite countertop. You'd need a diamond drill bit to penetrate it.


You can tell there is a layer of mostly just epoxy on top. One thing I had assumed but didn't know for sure was whether the epoxy would wick up the sides a bit. They did, but that should not be an issue later. I'd like to avoid the layer of epoxy on top on the real pour if possible, I assume all I can do is keep testing the mixture so I don't have excess epoxy after the mix. I think I was closer to 20% on this run, so may 15% should be my next goal.


A better shot of the side.

A ruler next to your “brick” would be interesting to provide a sense of scale.

[technodanvan]

That's what the can of soup is for!

[technodanvan]

Danny, this video shows how they fill the cavity between the speaker layers. https://www.youtube.com/watch?v=wZijzINOtCU

That's really interesting Steve, so they're probably just using a form of liquid rubber. I think someone else here mentioned doing something similar in a DIY design. I see it's readily available from McMaster-Carr too, so it's easy to get, though perhaps a little pricey. Granted, I haven't calculated how much one would need for a bookshelf-sized project. Being actual liquid though, you wouldn't need to keep the sides so thick since it's easier to pour.

Jon,

Sorry I didn't think about using a tape measure (or banana) for scale. They more or less fit the dimensions of the silicone granola bar forms I grabbed a couple weeks ago: https://www.amazon.com/dp/B07RLWBTNH

Cavity Size: 1.57 x 4.56 x 1 inch - though none of my pours were quite as thick as they could have been. The heaviest one was 159 grams (about a third of a pound).

Edit...actually I was looking at one of the bars I made and realized it's nowhere near an inch thick, it's closer to 9/16". They also measure exactly 1.5 x 4.5 inches. Using the new (correct) measurements I get a density of 2.55 g/cm3, much better than what I had originally calculated, and right on target. This, despite some epoxy resting on top.

[JonMarsh]

For that size piece, how's the exothermic behavior with this epoxy you're using?

[technodanvan]

Unfortunately I don't have a temp gun, so I couldn't check it quantitatively. However, I do not think at this thickness there would have been any substantial exothermic reaction, at least if the manufacturer's claims are to be believed. I do have to say the curing process is taking an awful long time for the pure epoxy though, so I'm wondering if I messed up the hardener ratio somehow; in theory it should be setting faster due to the heat in my garage, and it just didn't do that for any of my samples. Even today it's not quite set, not even for the thinner sample.

Edit:

I started work on my vibration table today. The parts:


The initial assembly:


So I say 'initial' assembly because the table vibrates way too much. It easily walks while knocking off anything on top of it. I'm thinking about attaching it to my workbench so it has a hefty base. I also think I need to add rubber sheets to the top...and maybe some low sides to keep things from falling off. The other option (or maybe this should be a 'both' situation) is getting an AC speed adjuster, though my understanding is they don't usually work well with these low power vibrators.

[technodanvan]

Just a quick update, I think I've decided to wait to pour the epoxy until winter. I'd keep the epoxy and the forms out in the garage until temps are in the 40s-50s and mix and pour in several sessions. This should keep any exotherm reaction under control.

theSven pointed out a few weeks ago my sand is kind of weird, and it did not really occur to me until he said it. I purchased concrete sand, which is clearly different from play sand or beach sand. I'm unsure if there is a difference in the end product, but play sand would be more consistent and may produce a nicer product. For the purposes of this project though I don't think it'll matter. I also noticed during his visit that one of the speakers appears to be around 1/8"-1/4" taller than the other, which impacts the baffles I already have. I'm honestly not sure how that happened unless the 1/4" MDF bowed somehow, which is certainly plausible. I'll be painting the cabs all around despite the baffles being bamboo so any cludgy method I come up with to fix it shouldn't be visible.

[JonMarsh]

Stuff happens.... slow work takes time. Crossing fingers about the winter thing...

[technodanvan]

So these projects will be picked up again quite soon as I need to make room for the Crescendos. Status for all three kits are below.

1. Overnight Sensations TMM: The towers are complete and crossovers installed, just need to install the drivers and the terminals...after I figure out what finish to use and apply it.

2. Speedster TMM: Basic cabinets are complete and baffles are probably ready to be adhered to the cabinets, after crossovers, stuffing, and wires are installed, of course. I need to figure out a finish for this as well.

3. Kermiskas: The cabinet forms are done and just waiting for the polymer concrete pour. I'll probably tackle this before anything else as I'm curious how it'll go. Could be a disaster! Perhaps importantly, theSven had noticed the pure epoxy bricks had still not cured when he visited a while back - they were quite flexible, though returned to 'brick' form when released from tension. Since then, they apparently did cure. Only took a few months! Not sure how that'll play into the pour at colder temperatures in an enclosure, but we'll find out.

[theSven]

3. Kermiskas: The cabinet forms are done and just waiting for the polymer concrete pour. I'll probably tackle this before anything else as I'm curious how it'll go. Could be a disaster! Perhaps importantly, theSven had noticed the pure epoxy bricks had still not cured when he visited a while back - they were quite flexible, though returned to 'brick' form when released from tension. Since then, they apparently did cure. Only took a few months! Not sure how that'll play into the pour at colder temperatures in an enclosure, but we'll find out.

Only took a few months 🤣🤣🤣🤣🤣

Good to read that they did finally cure. The construction concept is really cool and seeing that in person was great. Hopefully they are ready to listen to the next time I'm in town out that way.

[technodanvan]

Well, I finally poured some epoxy today. I didn't really take any pictures since the process was kind of involved, but it was...not as much of a mess as I thought it might be. I calculated the mix at 8.5 kg of solids (67% sand/33% powder) versus 1.5 kg of epoxy and mixed it with this honking thing. I was surprised the cordless drill could handle it, but handle it, it did. I actually had a hard time holding the mix bucket between my feet there was so much torque available.

Once I mixed the 8.5:1.5 mixture I realized I didn't have near enough epoxy. Maybe it's due to the cold (something around the mid to upper 40s this morning) but the mix was pretty dry. I decided having something that could pour would be preferable, so I doubled the epoxy in the mixture. Turned out a bit better, but in the end, it wouldn't matter.

I had no intention of completing either speaker today which is good as I don't have near enough epoxy to do so. Ultimately I poured about an inch or so. Yeah, the whole 11.5 kg constituted about a single inch along the back of each speaker. I also discovered only the top of the mix prior to settling really 'poured'. For the second speaker I used a large mixing stick and scraped the mixture into the gap. It's probably not a coincidence that one weighs a bit more, at 13.3 kg (30 lbs), but it's not like I was being exact anyway. I'm predicting three more pours of similar size will be necessary to fill the boxes completely, with maybe a fourth small one of just epoxy to even it up. That would work out to somewhere around 70 pounds per speaker!

I only have enough epoxy for one more pour, but should have plenty of solids to finish the project.

I don't think I'm doing this again, unless it's for a REALLY special speaker. It's a lot of extra work.

[technodanvan]

I tore down my router table today to clean up the lift and begin the installation of my new motor. I didn't take any pictures of that since it's not directly related to a speaker build (though it is a necessary step), but as I was doing so I remembered I never posted a few pics of my second pour. So, here's that. I have enough epoxy for one more round which I think should be enough to top them off.

Here's the mixed aggregate I'm using. Not exactly play sand, but it seems to work like a charm. 67% sand/33% powder.



And here's the mixture nearly ready to pour. I believe this picture was taken with only Part A of the epoxy mixed in. My picture of both Part A and B turned into a movie somehow.


Finally, I opted out of using the funnel this time as it was simply far too slow. I just scooped and poured using smaller containers.


Edit: For Jon, I do not believe I had any exothermic reaction again, and this time the pours were six inches thick. I think the combination of doing this below the recommended temperature and having a dense mixture helps keep things under control.

[Steve Manning]

Hey Danny, you could always post some router table stuff in the woodworking tips section.

Looking good on the slurry pour!

[technodanvan]

Well typing that post up apparently gave me some motivation this morning, so I completed a third pour...only to discover I was just a little bit short on the mixture. I'll need to do one more small batch of the mixture to wrap this up, then probably use a different epoxy to adhere the baffles as the 'deep pour' stuff is probably not appropriate. I've been giving it a week or more to set in between pours, so maybe I'll be done with it by February. We are at 50 pounds each as it is.

I am, however, also thinking about cladding all sides except the front with 1/4" baltic birch as the MDF has gotten fairly beaten up when I move them about. Thoughts on that? It'd make the baffle a hair wider than designed, though I will be putting a fairly large roundover on them.

Hey Danny, you could always post some router table stuff in the woodworking tips section.

I might do that, I took a few pics today but couldn't get much done.

[technodanvan]

More progress today. Topped off the epoxy in the cabs and lengthened the baffles a hair. I need to find some kind of high build epoxy to attach the baffles now...

[theSven]

The build is coming along nicely! Looking forward to seeing how these turned out. What is the weight now that you have the epoxy in? +5 lbs a cabinet?

[technodanvan]

Unsure what the final weight is, I didn't want to move them at the time. Probably only a pound or so each, there wasn't much left to top them off. I still used the sand mixture and actually finished the 50 pound bag of sand, meaning I used about 25 pounds of powder as well and around 9 liters of epoxy.

[technodanvan]

Minor progress again. I epoxied the baffles to the cabinets. I'm not sure how much I trust the '5 minute set time' on the Devcon, so I'll wait a few hours (at least) before cleaning up the edges. Then I need to decide if I'm going to call them done or laminate some hardboard or 1/4" BB to the sides and top/bottom.

[technodanvan]

Minor update: I decided to skin everything but the baffle with 1/8" hardboard. It covers up all the stains and such from the epoxy drips and provides a clean surface for sealing and painting. I thought I could just use the weight of the cabinets to 'clamp' the hardboard while it dries, but either the cabinets aren't quite square or the tables I have them resting on aren't. Probably both. So I'm clamping like normal.

Anyway, no pictures of this process at this time. I have the rear and sides done now, and will do the bottoms today. Speaking of the speaker bottom, I haven't quite figured out what kind of feet to use since I can't exactly drill or screw into the epoxy granite. Tentative plan may be to create my own stands, or modify something like the below from Monolith. Instead of feet on the speaker, I was thinking about putting 'feet' on the top of the stand, perhaps with adjustable height in the event i need to tilt the speakers up or down slightly. I don't know for sure, but I'd rather not have to design and make stands right now as progress has been slow - I need to get to the Crescendos if I'm going to get them done by October, and I have yet another speaker project I want to start on as well (though that is pending funding at the moment, and needs its own modifications).

As an aside, Monolith claims the speaker stands can only support up to 75 pounds. I shouldn't quite exceed that, but even still I think it's an odd number to choose given the design - it should clearly support much more than that unless the pillars are tinfoil-thin! I wonder if it's more about how tippable they may be when loaded and if so, how they calculated that.

https://www.monoprice.com/product?p_id=24794

[technodanvan]

In other minor news, we (my wife and I) elected to not finish the Overnight Sensation TMM at this time, so I went ahead and installed the drivers and such so we have working speakers. The tentative plan (per my wife) is to have them painted deep green and have some artsy person draw some mushrooms on the sides. These are going in her study, so she's calling the shots.

That said, I'm not sure I want to have them finished as they currently sound bloated to me. It might be speaker placement at the moment - one is in a corner with close boundaries - but my normal towers don't sound like this, bass is emphasized in certain areas of the room but not what I would consider 'bloated'. It could be because they aren't broken in yet, so I have them hooked up in the living room for music all day.

I'm not sure what else it could be. This was a Meniscus kit, so crossovers were pre-assembled and hookup was intuitive. I did move the port to the front - which according to the plans was okay to do - and maybe it's possible I put an incorrect amount of stuffing in it?

[theSven]

In other minor news, we (my wife and I) elected to not finish the Overnight Sensation TMM at this time, so I went ahead and installed the drivers and such so we have working speakers. The tentative plan (per my wife) is to have them painted deep green and have some artsy person draw some mushrooms on the sides. These are going in her study, so she's calling the shots.

That said, I'm not sure I want to have them finished as they currently sound bloated to me. It might be speaker placement at the moment - one is in a corner with close boundaries - but my normal towers don't sound like this, bass is emphasized in certain areas of the room but not what I would consider 'bloated'. It could be because they aren't broken in yet, so I have them hooked up in the living room for music all day.

I'm not sure what else it could be. This was a Meniscus kit, so crossovers were pre-assembled and hookup was intuitive. I did move the port to the front - which according to the plans was okay to do - and maybe it's possible I put an incorrect amount of stuffing in it?

I'm not sure if Paul comes around here anymore. I've never read a comment that they are sound bloated. After you break them in give us an update. If possible could you access the crossover to review the configuration?

I have always wanted to build a pair of these, as this was the first build I looked at in 2014 when I joined the site. Life came about and other priorities and I've never had the opportunity yet.

[technodanvan]

I think they're sounding better, but I'll need to switch back to my mains to be sure. Need to doublecheck the port dimensions too...I'm thinking about shoving a sock in there.

I'm definitely warming up to them but I want to be sure it's not my ears that are 'breaking in'.

[xandresen]

I don't think speakers sound different to a microphone after break-in, just to our very subjective ears. Takes me a week or two if I've made a big change.

In the photo the speaker is placed very close to both the side and rear walls. If your main system has its speakers 3+ feet out from the walls, that could be the difference.

Our hearing starts to hear the echos off the walls as part of the direct sound if the delay time of the echo is small. I don't recall what that delay time threshold is.
This is one of the reasons for the usual recommendation to have 3+ feet spacing.

I've often heard close spacing also affects the amount of baffle step correction needed, with none needed for a small cabinet right against the wall. Have never experimented with this.

Take them out to your main listening room and compare with them side to side to the mains.

[technodanvan]

Well, technically this is my main listening room - for TV and movies at least. Maybe 5-10% music. In any case, I fixed the problem. I noticed that while pop music sounded more or less fine, rock and metal did not. Guitar riffs in particular were greatly impacted. I went back and looked at the crossover diagram and realized I had assumed reverse polarity of the tweeter was taken into account with the markings on the premade crossover boards - it was not. Swapping polarity has fixed that problem for the most part. I still think they're a tad heavy in the bass department - which Paul had designed into the speakers on purpose for the fun factor. They do have pretty darn impressive bass considering what parts are used, and I'm fairly excited to get the Speedsters done to see what they can do.

I might get them into my music listening room to compare directly to the Ardents. Obviously a big differential in virtually every category of DIY speakerbuilding, but I don't have much else to compare to and while that room isn't perfect either, at least the L/R boundaries are identical.

[xandresen]

Good catch with the reversed tweeter connections.

[theSven]

If I recall correctly, the mid on my Ardent D's is reverse polarity and Steve reminded me when connecting the speakers to make sure that connection is opposite of the woofer and tweeter. Otherwise it will not sound right. At least this was an easy fix and a simple review was all that it took! When I get out your way again it would be great to hear this build.

[technodanvan]

These really are very impressive for their size and pedigree. I no longer have any qualms about placing them in my wife's study/office. Need to figure out an inexpensive, compact method of powering these with Roon though, and probably Airplay for her podcasts and such.

I'm a sucker for NAD, but I think the price point is too high for this project. Maybe I can find something used.

https://www.crutchfield.com/p_745C700/NAD-C-700.html?tp=34948

I WiiM Amp might do it too...don't know about Roon though. Much more affordable at $300.

[theSven]

If you went with the WiiM then get a Raspberry Pi, install Moode on the card, then ssh into the OS and install Roon Bridge. That would be pretty cost effective to have Roon streaming over HDMI to the WiiM. If you want to 1 up that you could add a Pi2AES card and use the tos link to the WiiM.

[technodanvan]

My understanding is that several other WiiM devices natively support Roon - and that this one may as well at some point in the future.

[technodanvan]

A 2-month update!

Overnight Sensations: We started listening to more music through the OS TMMs and decided to stop shortly thereafter. My wife could tell something was wrong - TV shows sounded okay through them but music was an absolute mess, whether the tweeters were wire in phase or not. I need to try them in 'opposite' phase to see if I screwed up the internal wiring somewhere and bust out a mic to see what's going on. I think they are definitely promising, but I screwed something up, somewhere.

Keramiskas: I wrapped up the hardboard cladding on the speakers about two weeks ago and finally got around to routing off the extra overhang. First speaker went fine...the second did not. The bit was a hair loose and slipped down far enough to cause the below to happen. I have plans to either fix this or turn it into a feature on both speakers. I ordered a couple new woodpeckers bits to do the job - I wanted to be certain I had a very sharp bit when carving out an even divot.



After that screw-up I went ahead and used a very large roundover bit, probably taking 5-6 passes for each side of the baffles. Looks good, but I had a little tearout on the hardboard which will change my finishing plans a bit.



Edit: After seeing what Dave has done on his speakers, I kind of wish I had the capability to make 1/8"-1/4" veneers and had used those instead of the hardboard. Ah well, perhaps someday that will be part of my skillset.

[Steve Manning]

That sucks Danny, though I have been there a time or two myself. If you have some left over baffle material you could make a patch to drop into the divot.

[technodanvan]

I think that's the general plan at this point. I thought about making a rectangular notch in both speakers and inserting a piece of etched aluminum in there post-painting...and even thought about making it extend to the bottom of the speaker...but that sounds like a lot of work for questionable gain.