Are both drivers doing the same thing? Hiss at idle sounds more like an amplifier problem than a driver problem to me. Could it be that you never noticed the "hiss' until after the thump but it may have always been there? 

I am attempting to compile a table of mouth size, throat size, length and Fc for various horns.  The throat size for a K-400 (K401 is of interest. Can some good person out there measure the diameter of the port on a K55 with an inside measuring micrometer for me.  Please!  I think that all screw -on drivers of the type have the same dimensions.  Thanks 10E6, Wm Gil McD 

such a legend. RIP

Could you please send this file to me! Have the same issue. (mnatsak@gmail.com)

Tweeters/compression drivers will pretty much always be more fragile than woofers.  If you’re just hearing hiss at idle though I wouldn’t think anything is wrong.  Almost all high sensitivity drivers will have that when connected to amplification.

Just damp boxes and some water in the packing. 😕

I'm sorry if this may seem like a silly question but is it quite possible that I've damaged my RF-7 III's Compression Drivers permanently when I turned on my Purifi 2nd Gen 1ET6525SA amplifier?   There was an extremely loud thump when I powered on the Purifi 1ET6525SA amp which I think may have caused permanent damage as there is fairly moderate hiss coming from the Compression Drivers, it has happened only once but my previous Purifi 1ET400A amp exhibited much less hiss & the 2nd Gen 1ET6525SA is meant to have a substantially lower noise floor, I also have a monoblock Purifi 2nd Gen 1ET6525SA amp hooked up to my RC-64 III which exhibits much less hiss too, perhaps owing to the much smaller Horn size 6.25" compared to the RF-7 III's 8.5" size.   I'm using bare wire connections & had removed a bit more of the pvc jacket so the speaker wire ends were just under 20mm, I wanted to insert it further so the binding post wouldn't bite into the pvc jacket but perhaps whilst screwing up the binding post, the speaker wire was also touching the brass housing right before I powered up the amp which caused an extremely loud thump sound, are the RF-7 III Compression Drivers fairly robust & would be able to handle something like that momentarily?

I'm fairly sure that La Scala AL6 and Klipschorn AK7 are coming very soon.  No one would give a specific date, but my guess is this will be in a time period measured in weeks or months as I saw evidence that they are already into pre-production last weekend.  I can't say any more than this (and perhaps I shouldn't even have said this).  However, I see no reason to believe that these speakers aren't on track for release.   It helps to remember that the reason that these revisions are being done now is that the decades-old tooling for making the K-401 horn had finally worn out and could no longer be repaired.  Since a new tool hade to be made, the decision was made to finally replace this last old exponential horn in Klispch products with a modern modified Tractrix horn.  The tooling for that new horn (designated the K-406) was made.  So, Klispch literally has to release the new versions since they won't be able to make K-401 horns anymore.   I won't speculate on pricing as that's all it would be is speculation. The one thing I was told is that the DSP will be an optional item purchased separately.  So, if you only want to use the passive networks, you will not be forced to pay for the DSP.  However, after hearing both the new La Scala and Klipschorn with both the passive and active networks, I will again state that in my opinion purchasing the new La Scala or Klipschorn without doing the tri-amp DSP setup would be a monumental mistake.  The sound with the DSP is so much better.  It is not a small improvement.  Time alignment of the drivers makes a huge difference for the fully horn-loaded Heritage speakers.  It's why Roy originally wanted to forgo making passive networks at all.   Read my full report on the last Chief Bonehead class last weekend here.    

I’m surprised the moderators have not deleted these posts about your homemade Heresy and Forte clones. Before the forum became “Klipsch Censored” these types of builds were always fun to follow.  When I built the Super Heresys using Claude’s Super heresy recipe it was fun and results were amazing but the powers to be on this forum seemed to deem changes made by anyone but Klipsch to be something best not ever discussed here.

I’m curious what you used for the active crossover (DSP)?