I know it's useless, but I already bought it. In hindsight, a WBFK would do just fine in this design instead of a CI. This is my 2nd attempt :D.

I find that GQ is pretty decent by itself, but when combined with HODVTEC, the subbass bleeds slightly into the bass, which caused it to sound muddy. While cutting it further is not possible, I repurposed the CI instead to a highs which it gives the crisp vocals I look for when combined with the...

Ironically, I'm now using the CI as a highs driver by putting it in series with a 0.4uF cap. It doesn't add anything the HODVTEC can't do for the bass, and I find that the treble extension of the GQ is too weak, possibly due to my internal acoustic path design. It's never used as I expect it to...

  I don't actually use it for anything other than the low end, and I feel the HODVTEC is better than the CI as it has higher output even under a 2nd order lowpass filter to reduce the 1-2k hump.   Resistor is not optional...     I suggest you google RC lowpass filter. One main...

  I'm using a 2nd order filter with 100uF caps as per photo below, stacked twice, resistance is changed to taste as it controls the volume of the bass  

  The WBFK + ED driver with internal crossover. I would honestly prefer to adjust WBFK and ED separately which I will do when I go back to my first earphones (WBFK, ED, CI, DTEC), but for now I'll complete testing the HODVTEC, CI, GQ earphone without modifications.

I'm happy to report that I have gotten pretty flat response down to 20Hz now. In hindsight and during testing, I found that CI really doesn't add much for the sound, other than to make it slightly more fuller since it has a different response than HODVTEC. I think for ultimate bass, dual HODVTEC...

  It was open shell, considering only the front of the driver is embedded in the boot that I printed for testing. I'll certainly try blocking the vents tonight with some pieces of tape to see if that helps.   Also, the HODVTEC wiring diagram is quite confusing until I realized that the...

Maybe my ears just aren't sensitive to 20Hz... I'm using a HODVTEC so I'd expect reasonable amounts of sub bass.

Just asking, but has anyone managed to reproduce a decent 20Hz sine wave on IEMs? For all my tuning, I can only get a relatively flat response to 50Hz, and then rolling off to about 25-30 Hz before I lose all response.

  I would say if you have the time, go for it, but have you actually looked at the ear canal beyond the mold? As I understand, whatever you see up to the first bend on the mold will be solid acrylic, so it won't affect the sound at all. Only the parts that you don't actually keep in the mold...

Hm, I just realised that it does have a vent. What do I need to do with it? As long it's uncovered within the shell it's okay already?   Also, maybe you can just rearrange the layout a little to fit in all the drivers? HODVTEC is like a DTEC in size, so it's quite square from the front as...

It sounds as fine as a really fine thing :D. I'm going to add and ED for even lusher mids, which is what is lacking.   I've been listening to bassy songs to test the response   I recommend white clouds decaf, limit to your love, hotel room service and in da club as good sub-bass tests.  ...

If you like tight bass, consider using the DTEC. It's flat response helps prevent bass bloat as compared to CI, which is why I'm using DTEC for bass and CI for mids now.

Buy another! In fact, buy a couple spare!   Low impedance might give better sensitivity, but ultimately might compromise sound quality when driven with higher output impedance sources. While it's not needed to design some super high impedances into the earphone, my earphones have a higher...