2.5" Full-Range Desktop Speaker - Dayton Audio ND65-4

This is a small passive bookshelf speaker I designed for my computer desk. The design squeezes out every bit of low-end performance out of a 2.5" aluminum cone driver. Internal bracing and curved geometry help reduce internal reflections.

The walls won't shake, but they've got plenty of thump.

Settings:

- Top/Bottom Layers: 7
- Infill: 35%
- Perimeters: 4 (at minimum)
- Manual supports can be added to the port flare and the top of the speaker cutout to improve appearance slightly. Otherwise, supports are not necessary.

Speaker Parts (for a pair):

- 2 Dayton ND65-4 Full-Range Aluminum Cone Driver (PE# 290-204)
- 8 M3 Heat Set Inserts
- 8 M3x6mm BHCS screws
- 4 meters of 18-20AWG stranded wire (2m Red, 2m black)
- 1 meter random fishing wire
- ~200g acoustic fill (Poly-Fil , Acousta-Stuf, etc)

Assembly:

Add heat set inserts to the front baffle, ensuring that they are below flush. This will prevent air leaks.

Solder the positive and negative wires to their respective posts on the speaker driver.

Put the bit of scrap wire into the hole at the rear of the enclosure, then pull it out through the front cutout. Tape it to the end of the two speaker wires, then pull the scrap wire carefully out the back.

Add polyester fill or similar damping material. Loosely packed to the top (leaving 3-4cm behind the driver) will help tame internal reflections and improve sound. If you want to go all-out, pick up some damping sheet (closed-cell rubber foam) and adhere it to the walls of the enclosure.

Make sure the foam gasket is on the back of the speaker before screwing it down.

The crucial last step is to seal the hole at the back of the speaker. I used hot glue to form an airtight plug around the wires. Alternatively, a screw-type barrel jack or 3.5mm TS plug can be used for a cleaner look.


Update 1:

Added files for a thermoforming mold and outer ring to make a nice speaker grille. They are a work in progress. The instructions will (hopefully) remain the same. They require four 6x2mm magnets each (8 for a pair).

-The two mold pieces need to be printed with a high-temperature plastic (ABS/ASA/PC/etc) to prevent deformation during the forming process.

-The mesh sheets need one perimeter, zero top/bottom layers and low layer height (0.08-0.12mm). I used 25% honeycomb infill to create the mesh as seen. A lower-temperature filament (PLA) should be used.

-Set your printer's bed temperature to 100C. Place the bottom and top halves of the mold (flat side down) onto the build plate to warm up. After about 10 minutes, place the sheet in between the two halves of the mold with the top piece roughly centered. Wait 2-3 more minutes, then apply gentle pressure to the top half until the mold nearly closes. Take the mold off the build plate and set it on a table with some sort of heavy-ish object (old cookbook, in this case) on top. After 10-15 minutes, trim the flashing around the mold with flush cutters. You can optionally sand the outer edges for a clean edge.

-Press the formed mesh into the outer ring, then either use superglue or a soldering iron (set at ~220-230C) to adhere the mesh to the outer ring. Working in sections makes this bit easier. Avoid the areas around the magnet holes for now.

-Trim a small section of the mesh out from above the magnet holes, then insert four 6x2mm magnets. Finally, glue the magnets in place.