I used 5" woofer and 3/4" tweeter with amp board from Wondom/Sure-Electronics, similar to Dayton boards. Model of amp in each speaker is Jab3+ 2x50W with custom sigmastudio sketch on each. 1 master, 1 slave. The firmware is another story in itself and what i have provided should be used with care and has been made based around the drivers im using.

Can be used as stereo pair or as a singular mono unit.

If i get around to it have another version of firmware that utilizes an MCU to toggle between master and slave programs, choose eq presets etc. The idea is to have a modular amp design that can be used as a master, slave or passive unit.

I've been using these as my PC speakers and am extremly happy with the sound quality at all listening levels.

Design is modular so could be made as passive speakers using a crossover in place for the amps/dsp.

For I/O it has Bluetooth (master input), stereo line-in 3.5mm and RCA, and stereo line-out 3.5mm and RCA.
Spekers in each unit can be driven as Left, mono, or right so it doesnt matter which side is master. Line-out outputs full stereo. Output can be daisy-chained to active sub (or anywhere else) at any point in the chain if active sub has rca passthrough.

Master and slave controls are slightly different:

Master Controls: Master volume (Controls whole signal chain), Master eq Low shelf +/- 6db, master eq high shelf +/- 6db, and Left-Middle-Right mux.

Slave Controls: Gain trim (to adjust balance -6db/+9db), empty, Lineout LPF, and Left-Middle-Right mux.



Speaker Build:

Similar to my other build, and common technique found online. 
Fill speakers with plaster + pva, or similar deadening material. Epoxy 2 halves together. Sand and paint (or dont).

Back of speaker has a flench cleet style spot if you decide to add a wall mounting fixture or something similar. It is wedged shaped with an embedded nut so what ever is designed for it can be secured in.

Model has space for embedded magnets to attach a faceplate. I never got around to printing it out. If youre going to use them I would alter the model and just press them in after the print rather than pausing and printing them in. Printing them embedded caused some issues for me.

I attached dimensions of the drivers used.

(Step files include parts to be printed as solid modifier (100% infill/perimeters))
(Included the full/uncut and solid model, this could be printed with optimised settings as 1 piece if youre build volume is taller than 290mm())