@Outrider 6, hi James, just saw your PM, and yes there are updates and perspectives gained from personal and shared experiences.
It’s unfortunate that all of the shared information isn’t usually relevant until after you actually physically experience what is being discussed. We seem to need to find out for ourselves and then make the more informed choices, sigh.
The original project was with a pair of mint walnut Cornwall 2s which I very much regret cutting up. They are long gone to a very happy buyer but I hogged out a pair of “B-stock” Cornwall 1s that I got for a song some time later and have no intentions of selling.
What I wound up with and what I would do with a blank slate are two different things.
Since these modifications I have been fortunate enough to acquire a pair of Chorus 2s and KP-301s for comparison.
Compared to the K-48s in the other speakers (K-48-E in the Chorus and the vented K-48-KP in the 301s), the K-33 in the Cornwall leaves me wanting. K-48s are tight and clean, not as low, and they really like the juice to get hammering the way they want to.
I also don’t think the Helmholtz resonator / shelved port does the Cornwall bass any favours. You can alter the shelf or block a “port” to tune it but I think 4” round ports with tubes cut to the desired length would tighten up and extend the bass better. But now you are replacing the motorboard.
So what I came up with as the best possible solution was a pair of Crites CW1526C woofers.
The difference was night and day better than the K-33 in this application.
Lower lows and more output up to the crossover to the midrange. A win/win situation.
I also found some Klipsch tractrix tweeters with the puny magnet and black poly diaphragms for cheap and retro fitted them with DE-120 drivers. So now there is a tractrix horn on the midrange AND tweeter drivers.
Dave A’s LMAHL lenses would shine in this (or any other) application too...
One last thing was a 2x6 brace from the motorboard to the back panel and across the width of the speaker between the mid and woofer. I used a 4” holesaw every few inches on the studs to minimize the displacement. I also secured a small piece of 2x4 in the middle, vertically between the very back of the port shelf and the base of the cabinet to eliminate any vibration there.
The stock B-3 crossover (600 & 6000 hz) has had the caps refreshed. I did not notice a difference one way or the other, but I used cheaper Erse and Dayton varieties. I believe a lower crossover to the tweeter would sound better (5000 hz) and is in keeping with the direction ALL new Klipsch products are taking.
Having said all that, If I were to start all over from scratch, and according to my preferences there are things I would do differently.
Custom made braced cabinet with 4” ports and the biggest 2” throat mid horn I could fit in a 3-way for starters.
But if I was going to all that effort, I would try to design an as yet non-existent “CF-5”, having two 15” woofers with a K-510 in the middle crossing around 800 hz.
That, to me, would be the culmination of direct radiating speakers.