To Buy or to DIY, here is my question

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.

It is entirely possible to build a speaker that will easily outperform a commercial one for the same money, though it may not look as nice.

There are many designs available by great designers that provide the volume of enclosure required, the crossover schematic and the names of the drivers to use. To get them to sing the box can be really heavily braced and battened and the parts for the crossover can be upgraded.

With a commercial speaker there are many constraints that prevent them from sounding as good as they could. If the cabinet was braced and used lots of timber to quieten the walls then the volume of box would by necessity increase to accommodate the extra support. This then makes for heavy and expensive shipping and together with the extra size makes for a less attractive sale. Also the XO parts are chosen to 'do the job' so the components will be reliable but rather pedestrian in sound.

Even expensive speakers use low priced parts. For example the series tweeter cap may cost $1 each but for your DIY units it's not that much of a stretch to pay $25 each. So a good design, stiff cabinet and carefully chosen XO components and you have a fine set of speakers.

Someone mentioned using a prefab XO.  This definitely is not the way to go. The XO is the heart of the speaker.

Another approach is to buy a classic like the Altec Model 19  This is a brilliant speaker which can be improved by reinforcing the cabinet and rebuilding the XO. The battens to stiffen the rear panel should be mounted outside to avoid changing the port tuning. Just keep all values the same but avoid those nasty cheap white sand cast resistors and consider having the XO outside the box. Use low-mass speaker terminals and wire internally with single core OCC copper.

There was a thread that went on for years: 'the econowave' there is tons of info and reviews of various builds. A properly done speaker using a waveguide with a compression driver is impressive and IMO far superior to the ubiquitous me-too box with dome tweeter. Also many out there using the SEOS waveguide which measures as good as anything available with excellent measured performance. The transients from this type are startling and dynamics scary.

Remember Pink Floyd don't play through no stinkin' 1" dome tweeter. 😁

Try this:

@oldschoolsound, Well looks like we were recommending the same thing at about the same time. We have to accept that great minds think alike.

So Mr. Chorus, gotta be something in it innit?