Diy custiom fitted in ear monitors with 6 balanced armature drivers
In 2022 I wanted to make myself new ciems, after the pair I built previously broke. This time I desingend the audio channels and resonance chambers directly into the shell and printed it in one piece.
These iems have 6 balanced armature drivers per side. Consisting of two subwoofers, two mids, and two tweeters. All acoustic elements are printed in the shell, and the drivers can simply be slid in after solderig. To make the soldering easier I made a small PCB, where all drivers can be connected to.
Many thanks to the community in the custom iem therad in the headfi forum. The specific design used combines the MASM 5Av1 by Theodoric Paddlefoot with the Zobelception Circuit by dhruvmeena96. Thore Frenzel has a greap video on how to get to a shell from the 3D-Scan of the impressions. To get the tubes fit nicely, draw splines and used the measure tool to check their length. When the lengths are correct, sweep a circle of the right diamater along the path to get the tube.
To build iems you need a 3D-scan of your ear. Audiologists can make an impression of your ear for a small fee. To digitalize it, either find someone with a scanner, or try scanning it using photogrammetry.
| Componets | Specifics | Source |
|---|---|---|
| Resin 3D-Printer | ||
| Biocompatible Laquer | e.g. Dreve Lack3, Egger Lack LP/H | local Audiologist |
| Drivers | Knowles RAB 23033 | Aliexpress |
| Knowles WBFK 30095 | Aliexpress | |
| Knowles GQ 30783 | Aliexpress | |
| Sonion 38D1XJ | Aliexpress | |
| Connector | 2x MMCX connector | Aliexpress |
| Litz Wire | Aliexpress | |
| SMD Components | 2x 10uF cap, 0805 | Aliexpress |
| 2x 15R resistor, 0805 | Aliexpress | |
| 1x 10R resistor, 0805 | Aliexpress | |
| 1x 100uF cap, 1206 | Aliexpress | |
| PCB | JLCpcb / PCBway |
After printing the shell and assembling the drivers, glue a faceplate on the shell and sand the whole iem to a fine grit (I used 800). Then apply the laquer. It is important, that all areas of the shell are coverd well before curing the laquer. After it is cured a second coat will result in uneven transitions.