I like the direction you're proposing for the dual sub redesign. I'd love to replace my sub cabinets with something more appealing look than the standard box. I realize the cost would be crazy, though.
Thanks! Glad the general idea resonated. Or didn't.
The cost doesn't necessarily need to be crazy. In fact, with some thought, things could be streamlined pretty well. It does also depend on what finish you're gunning for. Seamless high-grade wood grain usually makes it tougher. Being able to combine materials and fill in gaps and then paint tends to make things easier. Trying to fit unhelpful geometry from prior efforts may make things harder.
So, let's imagine that you'd like to have something similar to the "sub only" image above, but perhaps without the corner rounds, and a flat top for placing other elements on.
I haven't fully thought this through and there are many possible variants, but for example you could make a simple shell, drop it into a mold with plugs, fill up the shell, and make it pretty. It might not be so bad.
A quick, imperfect take on it:
- cut or procure a CNCed front baffle probably 1.5" thick that includes side notches and the radiuses for the lead-in geometry of the woofer front exits, cut mostly but not all the way through
- cut or CNC some external framing structure that forms the basis of an alignment mold/jig to hold pressure, plus a few 2x4s and sheets of 4 mm ply (baltic birch, marine/meranti ply, whatever) for the sides.
- build the alignment mold/jig out of the above
- cut or CNC the end caps (top and bottom) of the subwoofer
- glue the end caps to the baffle
- add 3D-printed caster inserts to the base end cap if desired
- tricky part--create the port plugs made out of a first section in front of each driver, and a second section after each driver. The walls need to be smooth and have a draft angle, guessing 3-4 degrees minimum. If undercuts are needed the plug cores must be hollow to allow internal access to one or more bolts that hold the separate "undercut" sections so that they can be released before removing the plugs.
- wax the sides and baffle side of the port plugs and then screw them to the front baffle
- tack and glue a 2-4 mm sheet of baltic birch or similar thin substrate for the sides to the notches in the front baffle and the end caps (forming a complete outer shell)
- while the sides are being tacked on and glued, a second person is mixing up the "cement"--polymerized counter cement or one of those exotic epoxy mixtures of many particle sizes I recall home CNC-types exploring for their machine beds
- immediately set the shell down into the alignment mold/jig and secure to the jig
- add additional layers of ply if more layers are desired for whatever reason (e.g. larger outer radii), tacking them into place with glue to the outermost layer. Or it might be possible to have achieved this thicker outer skin before the wet pour starts.
- fill/pour the mold with chosen cement or epoxy mixture
- fill the back of the shell with the cement/filler mixture until about 1/2" below the "back depth" line
- attach one of those thumper/vibrator thingies to get the air cavities out of the poured mixture
- cover and let start to set. Apparently concrete likes to set slowly. If it's epoxy-based, make sure it doesn't get too hot and burn your garage down.
- at the appropriate time interval (TBD), pour the final 1/2" or so of depth using a self-leveling cement to make getting a clean back easier. The port plugs could have back radii plates that soften the rear airflow, so this would allow pouring right up to the tangent more easily in a second step. Or you could drop in a wooden back.
- release the attachment bolds and undercut pieces, then remove from the mold with the help of 2 or 3 or 4 of your strongest friends
- remove the plugs and then cut/fair in the front port openings
- grind off any other burrs than may have occurred, round off edges, fill in tiny voids with a filling primer, then paint in such a fashion that even nlitworld has serious sub envy
Since this approach maintains an all-wood exterior for at least the skin, you could go also choose a fancy wood for the external veneer and baffle.
Once such a "mold and plugs" combo is created, making the second and thirtieth sub is much easier. You could make several subs for yourself and local friends, then send the slightly bulky but relatively light mold/plugs to the next eager OB bass devotee. Or have several sets in circulation.
After the mold and plugs are created ($1-5k?), the raw materials for the each sub chassis could be in the $100-300 range. Possibly less if the mold where for casting the whole thing in one shot.
With appropriate geometry and flexibility/complexity of the molding components, you could integrate an MTM on top as a seamless element. But this post is way too long already.
