9 years ago, the InDIYana widebody theme led to one of my favorite designs, the Indium 7 - which was generally a take on the Infinity Kappa 7 from the late 1980’s.
One way to meet the requirements of the 2026 theme is a 4-way, which also happens to have been a feature of the Kappa 8 and Kappa 9 variations. Looking at my current driver selection, I think another Infinity Kappa - like design is a real possibility.
The 1.5 cu ft internal volume limit wouldn’t be a good option for most 12” woofers (which the Kappa 8 and 9 variations used), but if we consider smaller woofers, then more options open up. I recently picked up some NLA 8” Peerless woofers (830491) that should do (based on preliminary modeling) 31 Hz F3 in 1.5 cu ft with a very reasonable tuning and plenty of output capability. The Kappa x.1 series had vented, trapezoidal cabinets, so that should work here. My design would have to have a narrower baffle than the original 8.1’s to maintain the required internal volume.
For lower mids, I have had some Peerless GBS135 5” dome woofers on the shelf for a while waiting for another Kappa-type project. Looking at the AudioExpress testing on those, I think they will work well up to about 1 kHz, which is about where I need them here.
Tweeters will need to be some sort of planar/ribbon design to keep with the Infinity Kappa theme. What would be ideal for me is if the old Wal-Mart ribbon tweeters I have on the shelf would do the job from 5kHz and up. If not, I still have a pair of BG Neo3 PDR’s or little AMT pod tweeters that could work (or I could resort to buying something).
For upper mids, I don’t have any smaller dome mids in my current inventory, but I do have a pair of discontinued Techtonic BMS drivers that will cover the 1 kHz to 5 kHz range and integrate well to a small ribbon/planar above that.
Here is the proposed driver lineup. If this project comes to fruition, it will be the Indium 8.1 Slim
