MTM Transmission Line Speaker

This is a tower MTM transmission line build. It was surprisingly large, but also surprisingly successful. I used about 5 kg of filament and bunch of patience.

I printed it with 2.4 mm walls, 4% infill and some supports attached to the base plate in PLA-CF. I'm not sure if the PLA-CF was necessary and was a LOT more problematic than ordinary PLA.

I was very happy with the result however. A few flaws occurred in the first layer because of the PLA-CF but I think they are barely noticable.

I used a Hivi rt1 3we planar ribbon as a tweeter

https://www.parts-express.com/HiVi-RT1.3WE-Isodynamic-Tweeter-297-421?srsltid=AfmBOor28fyrhkTeEmJRIHzESSo-vwhjDl0tsOXn4vQVeHC_tmq8RrGR

The  planar ribbon is in series with a 2 ohm resistive load for a total of 2+6 = 8 ohm resistance

and 2x RS100P-4 4" Reference Paper Woofer 4 Ohm

https://www.daytonaudio.com/product/1222/rs100p-4-4-reference-paper-woofer-4-ohm

The two drivers are in series for a 4+4 = 8 ohm resistance

and a 3000 Hz prebuilt 2x crossover.

https://www.daytonaudio.com/product/594/xo2w-3k-2-way-crossover-3-000-hz

I forgot what resistors I used.

The crossover sends the signals in parallel so the amp sees a 4 ohm equivalent 

There's room at the back to screw in the crossover board.

The flat mounting flanges for the speakers are printed separately and glued in place. I loosely stuffed the the transmission line with poly fill prior to gluing.

I've included my in room response, no EQ playing white noise. Data recorded using my phone mic.