Hello! I did not post here for quite some time, but I've just finished my universal in-ear headphones now. Some of you were curious about the design and the sound, etc. Here is a picture of the headphones (with a temporary cord) and a frequency-response curve of the sound.
To begin with, this is still a prototype, but a fully functional one. I have made the design in 3D (with Onshape) and then used the service of 3D-Hubs to print it in black resin. The result was very successful I think! But it still won't be in the same class as injection molding or other mass production techniques. However, it works very well for prototype use.
In the internal design, I only use a single driver (Knowles SR balanced armature) and an electronic filter in conjunction with an acoustic filter. This combination beats everything else I tested before, so I'm very pleased!
Now to the sound, I can only say that I am extremely satisfied! It's a crystal clear sound with a good 3D soundstage, as the sound both gets wide, deep and you can almost notice things up and down in the mix. The music becomes alive without being too intrusive. Very well balanced sound with very low noise, deep sub bass and very good high frequency extension. The only thing that's "bad" with these is that they are hard to drive. The volume has to be set high, so they are not the most easy to drive headphones, but works perfectly well for me with my phone. Because they isolate sounds so well it is almost like wearing a pair of earplugs.
If you look at the frequency curve, you may find it to be very strange, but that 6500Hz dip is very intentional. Unless the measured program or microphone is broken, that area needed to be removed. My ears would bleed from all the "S" sounds otherwise.
Thank you for all the help in this forum! I really appreciate it!
/Anders