To Buy or to DIY, here is my question

That is a pretty cool choice, I was gonna build that one and then decided against it as I had a hard time with the non-90-degree cuts as I did struggle with that on the gluing side on my center channels, I had to do a redo and went square.

My advice in the gluing is to make sure you have 2 extras helping when it comes time and do 3-4 dry runs with them before doing it. If you do a nice job on the cabinets, consider going to a cabinet maker to laminate and finish.

Good luck

You've got the budget to do the Linkwitz LX521 kit.  Not counting amplification, your cost will be around $3500.   Your choice of amplification will have a lot to do with the final project cost.  This will be your "forever" loudspeaker.  Trust me.  Easily stands up against any $50k+ commercial product.  Just friggin' amazing.

They look like audio frequency transmission towers...  So your best bet is to take them to an auto body paint shop.   Here are some images of a the CBT36 kit (I was not impressed with the sonics) a friend built.  They look incredible.

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mod_asored,

The locking miter takes a little bit of math to get your joints right.  Then add a tapered cabinet and you've added a degree of complexity to it. 

Another benefit to this joint is it holds whatever adhesive you use well as opposed to a traditional mitered corner. 

I'n not veneering but instead opting for a high grade piano white paint finish. The front baffle will be most likely an Italian graphite colored leather with chrome plated brass trim rings for the drivers.

That Audio Technology woofer 10C77 is the main reason for this speaker build. It is an amazing performing bass driver. 

I gravitate towards open baffle speakers sonically but they tend to look butt ugly aesthetically. 

Have you heard the  Linkwitz LX521  personally/

chorus,

As many have said, DIY speakers can be rewarding, frustrating, a great learning experience and worth it in the end.  Mine, basically a modified Altec Model 19, took longer than I planned to get all the details right and allow for a learning curve, but I’m pleased with the end result.  

Since you’ve been doing some research, you probably know these things, but here’s what I learned along the way.

Cabinets:  

Mine are 3/4” 11-ply void-free Baltic birch - see my Audiogon aviator, or whatever you call it.  Not having the ability to make fancy carpenter joints, corners have 1-1/2 inch wide 3/4” Baltic birch strips used to brace all around the edge of the sides/front/back and then pocket screwed into top and bottom pieces.  Also a complete circle around the middle which is tied together with a brace that goes from front to back.  

Diagonal pieces on sides, front, and back to dampen cabinet resonance.  Lots of glue and wood screws and then all corner seams caulked.  

Back is removable, (required as the woofer is rear mounted and I wanted to have access to tune the ports), and attached with threaded inserts and machine screws every 3 inches.  Speaker gasket keeps the removable back air tight.

I cut each piece as best I could with some margin to spare and then took them to local cabinet maker to get everything matched and square.

To add some dimension to the look, the sides are recessed 3/4” on the sides and 3/8” from front and back edges.  The front and back panels are recessed 3/4” from top/bottom edge and 3/8” from side edges.  Speaker and port cutouts edges are beveled.  Not everyone’s idea of good looking, but better than a plain wooden box.

Danish oil provides a nice and durable finish without brush marks.  Others have suggested spraying the finish on, especially if a color is used, or you can build the corners flush and then add veneer depending on what you prefer.  I needed mine to be simple.

The cabinets are each about 85 pounds without speakers, air tights and rock solid, yet still manageable to move around.

Regarding insulation inside the cabinet, follow the speaker manufacture’s recommendation.

Crossovers:  

Nice to be able to choose capacitors based on their sonic characteristics.  As other’s have said, it is very important so use a proven circuit for those drivers and the cabinet type and size they will be in.  Does Madisound have a crossover for these specific speakers? 

Use point-to-point connections with the capacitor, inductor and resistor leads as much as possible.  Use compression type connectors if you need to vs. spade connectors, (takes an extra solder joint), if all connections can’t be soldered.  

Solid core wire is much easier to use for short pieces to be “shaped” in tight quarters, to have clean ends and get a good solder joint.  Lots of opinions on wire size, but 20 gauge for short lengths in crossovers has been what those who know much more than me have suggested and worked great.  (You might be surprised to see what manufactures use vs. bigger is better notion.)  I did go 18 on woofer connections because I had it, but many output transformers in tube amps use 20 gauge on short leads to speaker terminals.  

Use stranded of course for wire runs to the drivers, 20 gauge is plenty for mid and HF drivers.  18 gauge if soldering to woofer; thicker wire can wick heat making it hard to get a good solder joint.  I’ve found quad eutectic silver solder with rosin core to give best results.  

Good luck, and let us know how your project goes.