I got two questions and an idea that could be idiotic or genius, I have no idea. Some relevant links first:
I'm building my first custom sub from the ground up, using this motor
The specs for the OEM voice coil for that motor is here.
The OEM VC is a perfectly fine VC, but using parts that were made to fit together ruins all the fun. Here's the voice coil I plan on using
So, question #1: Can I use the fancy PSI voice coil with this motor? Because if I do, there's going to be a sizable gap between the pole piece and the voice coil, and idk if that makes a difference. Even more worrying, there would only be a hundredth of an inch clearance between the voice coil and the top plate on either side, and I don't know how wide the tolerances are with this sort of thing. I also don't know if I can center the VC that accurately using only playing cards/index cards/whatever I have lying around at the time. Is it doable, or are my concerns well-founded?
Question #1.5: Say I can't use that voice coil, do you guys know of any suppliers of quality voice coils besides PSI/fixmyspeaker?
Question #2: I wasn't sure on what height my voice coil should be when I get around to gluing everything in, so I searched around a bit, and found exactly 2 relevant results. Both said the center of the voice coil should be level with the center of the top plate. Is that a rule I should follow, or is it bullshit? Because I'm not willing to risk like 120$ on what two dudes said 6 years ago on a forum I don't recognize.
Finally, and this has nothing to do with the stuff above, I was thinking recently about how to improve voice coil cooling. I only recently found out that people are using ferrofluid to improve cooling. Now, the issue with that is ferrofluid was never meant to act as a medium to transfer heat between two surfaces, nor was it meant to withstand high temperatures. I mean, I haven't read the msds in a while, but I'm pretty sure ferrofluid is just some ferromagnetic dust suspended in water, which evaporates eventually.
No, what you need is something designed for that. Like Arctic Silver, or whatever your favorite thermal compound is. Just a tissue-thin layer is all it takes. Friction is the most obvious issue, yes. But don't underestimate the power of even an entry-level subwoofer. For example, I ran the numbers on an RF P3D4 and found that it produced a whopping 56 pounds of peak force. So maybe a little friction won't make much of a difference.