Classix 2.5 Build Thread

[Waldo]

I'm about to start building a pair of Classix 2.5 speakers, its been a while since I did a build thread for any sort of project I've made (elsewhere, woodworking forums). Recently I finished building a Wifi/Bt boombox that was my first foray into speaker building, though I've been a hobby woodworker a long time and have built quite a bit of furniture. I'm currently nearing the end of a cabinet build that's styled like an old 50's/60's Hifi, but meant for charging devices (tablets/computers/video game controllers/etc..), with the speaker fabric being used to prevent excessive heat buildup.

I chose the Classix 2.5 because they seem pretty perfect for me. These speakers will likely be 100% for music; they are going to be used in the basement (office, workout, and video game space). I listen to all types of music, but mostly rock; I prefer live recordings (Phish/Dead/Panic esp) over studio stuff, low quality recordings are pretty par for the course, especially older "bootlegs"., I do turn it up a fair bit and occasionally will crank the hip hop. My 3 boys love dance parties and they aren't so into my lame dad music, modern pop for them.

Spouse approval is somewhat of a factor in design, but this space is more man-cave-ish so I'm not tethered to living room design sensibilities. But overly large isn't going to fly either, hence why I chose the Classix 2.5 and not something bigger. Right now I'm using some circa mid 90's small Sony towers, the glue lines are failing (seriously... they couldn't splurge half a cent for legit glue) so I've got them held together with clamps, and they never really sounded even mediocre to begin with (bottom of the line model, lol). Those were the wife's, my Cerwin Vega 12's weren't welcome to come when I moved in with her long ago, that's what a good speaker sounds like to me (yes lol, I'm not real experienced in the ways of good sounding speakers, but those things could rock).

I'm planning on using a baltic birch stack lamination much like the the boombox I made (I've been kicking around the speaker idea in my head longer than the boombox, the boombox was designed to go with what I wanted to do for the speakers). A couple earlier pieces I made, a C table (stand for the boombox in the pic) and a NAS also use the stack lamination technique; both the NAS and the boombox are pretty heavily carved, which is what I want for these speakers as well. The NAS is kind of part of my stereo system; moreso though location and potential use than any real use.

Some ideas I've kicked around are:
- a much larger version of the NAS (sort of a stylized tiki thing)
- a big mixed lamination (like the C table stand the boombox is on) where I come up a pattern mixing a wood in with endgrain baltic birch; perhaps a soundwave or a game of tetris
- a relatively normal box criss-crossed with strip inlays of cherry and walnut, sort evoking the look of Eddie Van Halen's guitar
- a big giant 1000 layer skateboard, with trucks and wheels (epoxied solid ofc) as the base; I might do that for a kids BT speaker one day

I settled though on a design where the base layer and top layer are solid wood, with a big horizontal stack of BB endgrain in-between, like a sandwich. Near the top and bottom a few layers will be solid wood, like pinstripes. Leaning toward cherry as the accent, but I have plenty of walnut too. I'll heavily round the corners of the sides and carve a subtle relief around the speakers. The port will be front facing.

I'm not planning on making grills or adding any provisions for them, but I'd love to find chrome trim rings for the speakers. Only downside of the Classix is the woofers are hideous (relatively speaking), I think a trim ring would go a long way. The mesh trim used in car audio could work too, but you never see them in home speakers. Seems like I will be hunting for the perfect trim for the speakers for a while, though wood is always an option.

I have the kit, it arrived a couple weeks ago. In a couple hours the box man will be bringing a shiny new tool I bought, a plunge base for my handheld router, which I'll pair with a jasper jig for speaker cutouts. Tomorrow hopefully I'll make it to the lumberyard to get a couple sheets of 3'/4" baltic birch plywood to get started. The stack lamination for the two speakers is going to be a long and tedius process. I'm not done with the previous project I'm working on in the shop, but I can do the stack lamination on the side while I finish it up.

[djg]

Here's a Baltic Birch laminated construction perhaps different than your thoughts. cjd's Ansonica.

[bigslim3k]

did you use any fasteners to connect the top of the box and the top of the port to the baffle or just glue?

[djg]

Here's the build thread by the builder, cjd, not me. I would have dovetailed the baffle pieces to the top.pieces. Not sure what he did. Probably glue.

http://www.htguide.com/forum/showthr...gman-s-theater

https://www.divine-audio.com/ansonica/

[Waldo]

Stack lamination naturally lends itself to box joints; you just intertwine the strips at corners. I think a dovetail would look weird, angles cutting across all the layers. But gluing directly is plenty strong; titebond on birch isn't going to fail.

He did a vertical ply alignment, I'm planning on doing them horizontally. It is going to be a bear to flatten; the boombox was small enough to run through the jointer, the speakers will have to be done with handplanes and sanders. Well at least it'll help get rid of the extra covid pounds.

[djg]

Yes, box joint is what I meant.

[Waldo]

Made it to the lumber yard and bought 2 5x5 sheets of 3/4" baltic birch for the lamination. I changed my mind a bit on the sides, going to do curved sides instead of straight; It'll be a little more challenging to glue up, but I think I can pull it off with dead tight joints; challenging builds don't scare me. Darn battery died on my saw and the cuts were rubbish (they don't cut for you there, and a sheet isn't getting in my car), but stack laminating is so material efficient its no big deal.

A little math:

30L = 1830.71 in^3. 30L is the stated size of the box.

However the interior dimensions of Paul's design actually is: 9.5 x 6.5 x 32.5 = 2006.88 in^3 = 32.8L Between bracing, the xover, and drivers, chances are its close to 30L onces finished.

My design is a more complex shape. I widened the baffle a bit to fatten it up and allow for a wide radius on the sides. 7.5" interior. The back will be smaller, 5", creating a teardrop shape. The math works a little better if I make it 9" deep instead of 9.5". This gives an interior area of 60.075 in^2 whereas Paul's design is 61.75 in^2. I'll need it to be 33.3" tall (interior) instead of 32.5". The sides and back will be 1.25" thick while the baffle is 1.5" thick. Part of the reason is so that I can curve the corners hard without running out of joint material, 1.25" allows for a wide radius.

Height though I where I still need to figure things out. I listen in my office chair mostly (+ its the listening I'm most critical of, I pay less attention to how the stereo sounds when I'm lifting weights) and I'm a big guy, my ear is 43-48" from the ground depending on how I'm sitting. Do I raise the speaker a foot or so; building it taller with a false bottom or build a tall base of some sort, or do I angle it back? I'm fairly far from the speakers at my desk (about 12') so a little angle will go a long way. I can offset each layer slightly to create the angle keeping the cross section the same, or I can offset only the baffle a bit, shrinking the cross section as I go up (which will also make the speakers a bit taller to hit 2K in^3 interior volume). I could just use tall adjustable spikes on outriggers to give a 5 degree or so slope, that's the easiest solution but least elegant.

Design is just some chicken scratches on scrap, but it works.

[Paul Carmody]

Send it, bro!

[Waldo]

I worked as a design engineer for many years and always knew that's what I wanted to do. Woodworking is an outlet for that that let me take the promotion and step back from design professionally, while still scratching that design itch. For the most part, writing it down is an unnecessary step, just some busy work I don't care to do.

Making some progress on the speakers. I've got the A layer templates made, one of the bottoms, and an A layer.



There will be A layers and B layers switching back and forth to make box joints in the corners. Solid wood layers will be a C layer, with the 3 different pieces, as I'll use miters instead of box joints to keep a consistent color (no end grain..). In total 9 different piece shapes will be needed for the stack lamination, which will be ~45 layers (4 pieces per layer, 45 layers, x 2 speakers; I have 360 pieces to fabricate, not including top, bottom, or any support).

Speaker #2 will be a bit behind. I'm going to be clamp limited eventually, that's when I'll start on #2. At first all my little clamps will be in play, once it grows out of them into the long bar clamps then the little ones will be free for #2. The same will be true as well as it outgrows the bar clamps and I have to switch to pipe clamps.

The going will be slow though until I finish up the previous project I've been working on. Almost done.

[djg]

Holes and long dowels for alignment?

[Waldo]

Its not hard to line the pieces up straight as you clamp them in place.

I don't really care about precise edges, only the joints. It has to be flattened after gluing anyways. The pieces are all off the bandsaw rough except for the the faces where a joint will be.

[Waldo]

This is what work on it is going to be like for the forseeable future as I start gluing on layer after layer.



I have the B side template made, but I need to have the first layer glued on to make the front and back, I want to take real measurements from the piece.

The next layer will be a C layer. I've decided to go with Cherry. It won't have as much contrast as walnut (at least for 20+ years, cherry gets darker and walnut gets lighter with age, they will cross paths), but my cherry stockpile is much better than my walnut stockpile; I have a ton of 8/4 cherry that could come in play for a base, which I still need to figure out (the lower layer of ply is not the bottom of the speaker). I could always get more walnut, but prices have gone crazy and supply has been scarce; the lumber yard didn't have any when I was there to pick up the birch plywood, not even 4/4.

I'm going to remove some of the extra corner material after each layer is glued. I kept the corners square for gluing to make clamping easier.

Paul's case dimensions show the port 5" OC from the exterior bottom of the case. How much does that spacing matter? Could it be raised a couple of inches from the bottom?

[Waldo]

Here is a pic of a speaker I have on my design inspiration Pinterest board that's pretty close to what I'm building, shape wise at least:


Usually speakers, even the teardrop shape, have wood grain (or grain-like elements) vertically aligned, but I think a horizontal alignment is more dynamic, like a wing cutting through a cloud. The way I plan to mix a darker hardwood in with the BB ply layers (just a couple at the top and bottom, little dab 'l do) should exaggerate the effect. The top strips (2 each top and bottom) will be centered on the tweeter.

The speaker in this pic uses a downward firing port and I've seen it used in other classix 2.5 builds. As I think about the base, that is an option still in play. Though I would prefer the port fire forward; my basement walls are paneled and will start to rattle, aiming the port at them is about the worst thing I could do, aiming the port away the best mitigation. But I could aim it down and redirect it forward with the base.

[DeZZar]

Though I would prefer the port fire forward; my basement walls are paneled and will start to rattle, aiming the port at them is about the worst thing I could do, aiming the port away the best mitigation

Do your basement walls rattle when you point a hairdryer at them?

The rattling is going to come from the sound pressure level in the room created by the omni directional bass frequencies (or whatever resonant frequency your stuff rattles at, usually 'bass'). These aren't coming from the port like it's some sort of bass canon....aim the port anywhere you want.....it's not going to make a difference

[Waldo]

Its been a while since I checked in. I realized I was spending so much time on this speaker build that I was basically ignoring my last project when it was 95% of the way to the finish line, so I focused on that, put the speakers to the side, and finished.

Now I've restarted the speakers and am in a good groove on the build.



Have an assembly line basically going fabricating all the pieces and gluing the layers. Speaker #1 passed my smallest clamps so I started on speaker #2 now as well. It turns out the rough cherry board I was planning on using is fairly curly (unusual for cherry...), which makes it a pain to work, but should look nice once its high grit sanded and has finish on it.

I was going to go with a bottom firing port, but have reconsidered; the shaping around the passive radiators is my favorite part of my boombox, the way it magnifies the layers, I want that feature in the front. Soon I'll have to start working on it as the higher it gets, the harder it will be to attach it. Going to have to put in the cup for the wire attachments as well.

Even in a good groove, If I'm doing 4-5 layers a week I'm still looking at more than 2 months of work just on speaker #1 until I reach the top.

[Waldo]

I finished working on the port for speaker #1.




I opted to go with the front port due to the effect the carving around the opening would have and I'm really happy with how it turned out; it looks like a black hole warping space around it. In this shot the top is just placed on it to prevent interior lighting, I cut the top with the bottom and I use it to make sure I'm keeping the shape from drifting as I build up.

At first I was going to cut the port the kit came with, but that didn't look terribly feasible once I started to work on the port, it was a bit too flimsy for that, so I ordered some 2.5" pvc and some pvc dye. I realized that it won't really be possible to redye once epoxied in place or or sand it once dyed, so the wood shaping is sanded to 400 grit already, and I put a couple coats of lacquer on the inside of the port to give it more color durability and be cleanable.



To give it strength I made a brace for the rear of the tube. The front of tube is mounted in a wooden flange mounted inside the speaker. I used epoxy for all structural connections (except the wooden flange to the case, good ol titebond there) and sealed it all with silicone.



I took the time waiting for parts to arrive to work on speaker #2. I don't have any progress photos, but I'm almost done with the 2nd cherry layer.

[Paul Carmody]

That looks amazing!