DIY IEMs using 29689 (or equivalent) drivers

thingiverse

<h1>Tested and working design</h1> This is a pair of DIY IEMs based loosely on the original Etymotic ER4. *Parts List:* * BA Drivers: Bellsing 29689 $8.5 * Dampers: Knowles Damper $2.6 * Shells: 3D-printed shells $2 * Cable: Wire $1 * Tubing: Tubing $2 * Ear-tips: Foam $3 I got all of my parts from Aliexpress except for the 3D printed shells. You might be able to save more by buying from taobao but I couldn’t be bothered to buy through an agent. *Tools:* * Soldering iron: I used a TS100 set to 340 celsius. Any other should work * Blutack: to hold the drivers in place while soldering. * 3D printer: if you want to print yourself. Will probably be easier if you use an online shop. * Super glue: I used Loctite branded super-glue. It’s based on Ethyl 2-cyanoacrylate. I suspect most brands of super glue are the same. <h1>Details:</h1> __BA drivers and dampers:__ The original ER4 uses Knowles 29689 drivers with green dampers and 18ohm resistors in series. This design uses no resistors. I have used both Bellsing 29689 and Knowles 29689 in my builds. Their sonic signature are slightly different. I prefer to pair the Bellsings with green dampers and the Knowles with white dampers. You can probably skip the dampers if you use foams with built in wax guards but I haven’t tried this myself. Other than the 29689s, you can also choose to use the Sonion 2389s (same dimensions as 29689) or some like the Knowles 32257 or 32873 - any BA driver with a diameter of less than 5.5mm will fit. I will probably use the Knowles 26821 with white filters (same configuration as Campfire Orion) in my next build. Let me know of any good driver-damper combinations you have. __Shells:__ The model has a minimum wall thickness of 1mm and a minimum hole diameter of 1.5mm. You should be able to get them printed using most modern 3D printers. I used ABS but other materials such as PLA should also work. The grip between the tip and shell body are tight enough they probably don’t need to be glued, even though I did anyway incase they come loose. __Cables:__ You might choose to buy wires from aliexpress or salvage them from an existing pair of earphones. Re-using existing cables usually mean harder solders, but if you are salvaging from a nicer pair of earphones (such as the Apple EarPods), the added features (microphones, lightning connector) might well be desirable. During installation, tie a knot or install a strain relief to prevent damaging the solder joints. __Tubing:
__ A tight seal is imperative for good BA driver performance. To achieve an air-tight seal, I used tubings to attach the BA drivers to the shell: use 1mm ID 2mm OD tubing to form a ring on the driver, then connect driver to shell using 2mm ID 3mm OD tubing. The tubings are tight enough they don’t actually have to be glued together, but I did anyway incase they come loose later. __Ear-tips:__ You should be able to fit most tips designed for nozzles of ~3.5mm diameter. I use Comply T100s on mine, but I have also tried aliexpress knock-off T100s and they work quite well. Shure triple-flanges also work but I prefer the T100s.