Unfortunately those Infinity kappa drivers were very poorly made, and just about all have failed.
You can not install different drivers. Every driver has unique T/S parameters and small changes make the design not work.
So picking a new driver means a new design and build.
So to resurrect an old thread, I have this sub box (bought it from the Nebraska guy above, the picture of it is there) with an infinity kappa perfect 12.1. Non-dq version.
I have upgrade-itis and realized the driver is going on 12 years old. Still works, though.
Recently I discovered multiple subwoofer databases in which you input the Fs and other thiel-small (or something) parameters and it tells you what drivers are similar.
So according to these sites, the closest match to the perfect 12.1 is this bad boy:
RSS315HFA-8 12" Reference HF Subwoofer 8 Ohm
For under $200, it can't hurt to drop it in and see how it sounds.
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