Thanks! It's delrin! Soft yet durable.
In the original drawing, I believe it called for the delrin to be 0.002 inches above the brass section. I opted to make it the same height and to use plastic shims to set that height. I cut my plastic shims with a cricut. You can buy these on McMaster Carr in different thicknesses. I then measure capacitance and add or subtract shims based on the capacitance I'm aiming for.
I just bought a coaxial speaker so my measurements will be more accurate. But in my previous tests, the rear rejection is very nice. The low frequencies come through a little, but nothing unusual.
In an ideal world, the tuning would be the same on both sides but it's bizarre that isn't the case with my backplate design. I've now made a bunch of them and they are very consistent. It's so odd that it seems to sound better with a different tuning on the front and back. I'd love to understand why this is the case. Just happy I've found something that I've been able to recreate many times now.
Okay, in regards to the clearance ring (the little milled out channel in the delrin around the brass piece)- I missed this in the drawings when I originally machined my capsule. Funny enough, in my own Debenham thread, nobody else noticed it. Thank you for pointing this out. I'm so curious now how this would affect the sound.
I absolutely love this capsule in its current form but it's about 10dB lower output than other capsules. [USER=99825]@soliloqueen[/USER] any clue how this clearance ring would affect the output or the top end? I imagine it would have more of an impact on the high frequencies like the blind holes. I'm currently in the process of making another Debenham with the clearance ring implemented to test this out.
