Audio Stix TL Loudspeaker (Hexibase Remix)

thingiverse

Human: *Update: 2/21/20 I've enlarged the driver cut-out diameter by 0.4mm and reduced the cut-out depth by 0.5mm. New files labeled as v2.* Ever wanted transmission line loudspeakers, but you couldn't afford them, or didn't have the space, or were intimidated by audiophile snobs? Hexibase to the rescue, with his miniature transmission line design for Tectonic TEBM28C10-4/A BMR drivers. I've taken the original acoustic design and transformed it into an upright form that prints as one piece. The chamber volume, port cross section and port length all match the original. The only significant acoustic change is moving the exit of the port to the back of the speaker. There are STL files with and without integrated supports, and with and without a recess in the front surface, to accommodate a trim panel. I recommend 3 perimeters and at least 5 bottom layers, to ensure a tight seal across the roof of the chamber, which has significant bridges. After printing, remove the supports, feed the cable through from the small hole in the back of the base, and then fill the hole with blue-tack or glue. Plug it in and enjoy! **Tuning the enclosure:** As expected for a transmission line, straight off the bat, these sound a bit like a speaker on the end of a hosepipe. Playing around with an online tone generator and covering/uncovering the vent reveals a significant resonance around 650 Hz, which is the full-wave resonant mode of the port. About 5-10cm of acoustic stuffing fed into the open end of the port damps this resonance nicely and produces a pretty smooth output. If you're doing this yourself, I would suggest adjusting the stuffing using an online tone generator and comparing response at 650Hz and 150Hz. Covering and uncovering the vent will let you hear the effect of the port. You want to adjust your stuffing to damp out the reinforcement at 650Hz, without adding so much that you lose the additional bass output at 150Hz. Acoustic stuffing fiber works best, but as a stop-gap, fluffed up cotton wool can be made to work. (I also printed these in a configuration like Hexibase's original, the same resonance is present, I think it's just the inherent behavior of the acoustic design.) After doing this tuning, I'm happy with the sound quality coming out of these speakers. I've paired them with the Hexibase subwoofer with a crossover frequency of 150Hz, and it's a great match - they play surprisingly loud without distorting: https://www.thingiverse.com/thing:3875737 Note: this is a large print requiring approximately 270 x 270 print area. Update: I've added a split enclosure version, which can be printed in two parts and glued together, allowing it to be printed on a much smaller printer. Kudos to the man: https://www.youtube.com/watch?v=lU4_E83RwUw Fusion 360 Archive provided.