Triple BA Driver

After testing out the single driver IEMs, I tried out the triple driver unit with crossover, the GK-31732, as recommended by the DIY IEM subreddit and more specifically this post. When the author said the drivers would be a tight fit, he wasn't kidding. After trying my best, the SE535 shells barely "close." I couldn't get the back end to close up completely (the back lip of the shells wouldn't overlap, <1 mm), so for now I just taped the shells together.

Soldered the driver directly to the input.

Taped together.

Compared to the single drivers, this unit has far more bass (as I expected from the relatively massive woofer unit). At first I thought it was too bassy, but after realizing that my HTC One M8's "Boom Sound" feature added a peak to the bass and treble and disabling it, they sounded much better.

Also, it turns out that increasing output impedance of a source is bad, especially for balanced armature drivers (which I did by adding the 18 ohm resistors to the singe driver units). I'm going to need to tackle this volume/noise issue another way. There are adapters that add impedance to headphones, but I'm not sure if they are doing anything special other than adding resistance in series. I've seen some people using ifi's iEMatch, which is supposed to help reduce output impedance and reduce gain, which decreases volume and noise.

I'm just going to need better electrical isolation and an audio output with a lower noise floor and lower output impedance. I'll probably remove the 18 ohm resistors too (but this means they can only be used with devices that have lower noise floors).