Khornukopia

Beautiful speakers.

The screws appear to be #8 sheet-metal screws. The length will depend on the specific speaker. A problem with trying longer screws is that the dog-ear tabs are captive in the slotted and capped mounting bosses, but some designs have excess tab material that could be trimmed to fit the thicker ceiling. I don't have a picture of your exact speaker, I am just trying to help with ideas.

I like the symmetry of your arrangement, but for the sake of diagnosis, have you tried playing your sub woofer tucked into the corner?

Yes the mineral wool insulation does function properly as a bass trap while sealed in the bags. The plastic shrink wrap is not a barrier to the long wavelengths of the bass frequencies. It is actually recommended that bass traps should have a thin hard surface to reflect the high frequency energy, if you don't want a broadband absorber.

The transistor inside the glass tube is an interesting design.

The bass bouncing off the walls crosses paths with the direct bass arriving at your listening position and nullifies it. Same principle as noise cancelling headphones. I had a similar low frequency response problem because of the size and shape of my room. I fixed it by installing some bass traps. I bought some Rock-wool mineral fiber, sound and fire insulation, wrapped the bulky 15x24x48" bundle(s) in black fabric and placed them in the corners of the room. If you try this, save your receipts and leave the plastic wrap intact, in case you want to return the bundles of insulation because of how big they are. (Some people would buy more subwoofers, rather than fix the room modes with a large bundle of insulation.)

That response graph looks very respectable. Using a High Pass (subsonic) Filter is a good idea.

Some of the other rooms I have listened to music in, this past week.

The Cary Audio SLI-80 tube amp combined with a pair of Klipsch Forte IIIs sounded excellent.

Yes, and they look good.

Yes you can mix the new Klipsch speakers with your old speakers while you build up your surround sound system. The Klipsch speakers on your list above should work great with your nice new Marantz receiver.

Some homes have that condition where the deep bass is strong in the rear upper corners of the room, but weak at the listening position.

Your speaker cloud and the indirect lighting looks good. The Rockwool will also help with the sound quality inside your room.

How do you like your N-Core amps?

Many in-ceiling and in-wall speakers mounting ears can fit 1 1/2" thickness, so two layers of 5/8" plus the texture mud and paint is probably the limit. You don't really need a roto-zip guide, a pencil mark will do. Might be best to acquire the speakers that you will use and measure them, just to be sure your final installation is fun and easy.

I will try those for hanging some shelves. They look like a good design.

Very nice.

Good article. Here is a quote from about half way into the article. "All Class D modulation techniques encode information about the audio signal into a stream of pulses." So it may not be digital in the digital data realm, but it is definitely not analog like a vinyl album and Class A or A/B amps are. The article also has a paragraph titled, "Analog Devices Class D Amplifiers", but I get the impression that is a company name.

The metallic copper paint on the front of the mid horns was too shiny, and the screw holes needed to be hidden, so I veneered those flat flange surfaces.

Are you saying this about the TH sub in general, or about your system in your nine foot tall room, specifically?

@parlophone1, Thanks for the detailed description.

Those Klipschorns look very nice. The seller is in Seattle, home of speaker-lab, so using the word Authentic in the local C-L ad for previously owned speakers is probably good for the general public.

I have been wondering about this unusual problem since you posted last week. Glad to read that you fixed it.

Thanks for sharing your observations. Can you describe the listening room?

I see they sell both pieces, and other sizes too, so you can bolt together the correct adapter for your horn and driver combo. Their web pages may display different to you, depending on your browser.