First I want to say thanks to hifiside for opening this door to a whole other aspect of the hobby for me. I had always wanted to try to diy my own woofers but never felt it would be worth it. I built an 8” woofer using some of the parts resources he listed and I had a blast doing it.
So I know that there is a lot of math and science to transducer development, none of what I have any clue about. I took some educated guesses and dumb luck and ended up with a part that was what I wanted.
I was hoping to build a heavy duty woofer but not quite a sub. I used what was effectively a sub motor and spider with a short for a sub but long for a woofer copper coil on kapton, with a light poly cone and soft surround.
The result worked for what I need. I’ll post parameters and some measurements when I can. It is an 8 ohm driver, 84 dB, 9.5mm overhang (30mm winding length). Biggest downside is the 4 layer 2” coil with no motor treatments makes for a 4.4mH inductance at 1k, but playing it full range laying on the floor it really doesn’t sound ugly.
It models well, flat to 30ish in 1ft3 ported. F3 of 26.6, within Xmax to 150w down to about 28 hz. The motor is deep, pole is extended, and spider is stiff, so it should never bottom or jump the pole. I was beating it pretty hard with no enclosure to soften the suspension a little and had no mechanical issues.
It is no where as clean as hifiside’s assembly and has none of the cool custom parts he machines, but was fun and worked so well for me I am building a quad for a pair in the bottom of some multi-way towers.
Please forgive the random pic order.