Yep, it is ported... very atypical for KLH, but makes for pretty substantial bottom end!
This speaker pair was brought to me with the instructions: "Install a MATCHED pair of tweeters". When it came in, it had one original KLH tweeter, and a Radio Shack ribbon (looked like JVC manufacture) stuck in the other one. Being unsuccessful in finding a KLH tweeter to mate with the original one that was there, I decided to try something a bit different... and in went the EPI tweeters, which given the similarity in efficiency and required bandwidth (from about 2KHz and up or so) to the originals, work quite well...
The reason I referred to it being a "family affair", is because of the "common genetic heritage" of EPI (yep, that is a first-gen EPI tweeter) and KLH. Both Henry Kloss of KLH, AND Winslow Burhoe of EPI, came from Acoustic Research... in fact, it was the AR4X that DIRECTLY led to the EPI M100, according to Burhoe... he wanted to make a better tweeter, AR said no, Burhoe then went and did it himself...
So, it's kind of like having the 'best of both worlds'... arguably, the KLH woofers had the best combination of bass power and midrange "speed" of any of the "AR-successor companies" (EPI, Advent, KLH or AR), and the Burhoe inverted-dome tweeter definitely had a better combination of bandwidth, power handling, response smoothness and extension than any of the AR, KLH or Advent tweeters. And even though it could probably be improved by crossover mods, it sounds quite impressive just as-is. And, NO cabinet mods were required- in fact, the EPI tweeter fits SO EXACTLY into the grille cutout on the KLH 33 grille, that it LOOKS FACTORY- so that if the owner ever desired, and was successful in finding a second KLH 33 tweeter, the speakers could be put right back to stock.
But, it's cool, to see that it is indeed so "period correct" that many people don't even notice that it isn't a stock piece... if you can't make 'em original, at least make 'em look like they COULD have come that way!
Regards,
Gordon.