I came across a set of empty Infinity Kappa 8 enclosures a while back. I've had kappa 8's(first version) and thought that they were bass heavy, and a tad soft in the high end, although very nicely extended and airy there. I liked them.
But, rather than looking for parts to rebuild these to stock, I'm going major changes instead. A little appreciated speaker line, now "vintage" were the B&O S-line, the S-80, S-120's, etc. Little appreciated because the cabinetry was abysmal, bass almost non existent, and power handling poor. However the lower mid range through to the mid treble was wonderful!
So, my rebuild is a cheaters approach. I simply intend to take a set of B&O S-80.2 speakers that I have, and remount, time align them in the Infinity cabinets. A note on the drivers in these little gems - the 8" mid woofers use a 3" edge wound voice coil, and fully copper lined pole piece. The cone is a paper/felt composite with an exponential profile. It is, in it's range(not used properly in the S-80.2 btw) a very low distortion design, something like a marriage of Dynaudio and ScanSpeak mid woofers. It's also quite dynamic.
The 3" soft dome mid range was a SEAS unit, and is a great mid! I really like this driver. It is the best I've heard in it's bandwidth, although I'm sure the ATC, is better, as well as perhaps the new 3" Tang Band 75-1558SE mid dome? However, using these would require a total redesign, and how much better would they, could they be? I doubt much really...
The tweeter used on the B&0 is OK. It has very low distortion in most of it's range, but I it has slightly edgy, slightly rolled off extreme highs, and since it lacks a back cavity, little was done to eliminate the back wave from interfering with the dome radiating the front wave. It is not near SOTA these days. I'll either replace it, or drill out a back cavity(and spend an afternoon cleaning the magnet gap) and adding a back cavity to reduce reflections. I'm lazy, so will probably just update the driver. The design of the crossover is simple, and will require few changes to optimize.
That leaves the 12" hole in the front. Well, I always felt, and still feel that Infinitys capacitor bass loading is INSANE! I, for one, simply do not like the idea of running that low an impedance to my amplifiers. Instead, I've modeled some viable sub woofer options that will tune very low, and provide just enough low end lift to compensate part of the baffle step. I stick to around 3 db of compensation as opposed to the 6db of loss that actually occurs in free space. My room is NOT free space at these low frequencies, and yours probably are not either. I find 3 db to be a good compensation/compromise that effectively raises the upper bass while not over powering the room where room gain makes up the difference at low bass. Murphy wouldn't agree, I'm sure, but it's my room & my ears that matter to me.
I'll be looking for - Infinity Kappa 12.1 woofers, but not new, and not new prices, AND not beat to death in the trunk of someones car. These will work nicely in the Kappa 9 cabinets. OR, a set of Volfenhag 12" subs. Even better for my use, but again hard to find in good shape, and at a good price.
Anyway, when i get them together, I'll post pictures here. I will measure the response, not just model it, and will let you see that as well.
I'm guessing a couple of months before I get to doing the project, and posting pics.
That's my DIY project.
