Backbox for Klipsch CDT-5650-C II 6.5" In-Ceiling Speaker

[FriedChicken]

I just bought four of these speakers and I intend on building a backbox for them. The overhead and price is minimal enough that even a marginal improvement will justify it.

Sonance publishes schematics for their 6.5" in-ceiling speakers under "Medium Acoustic Enclosure" here:

Visual Performance Series Acoustic Enclosures

www.sonance.com

*Click on CAD file download, it contains a PDF

Polk Audio officially recommends a 1.5 cu. ft. enclosure for their 6.5" VT-60 in-ceiling speaker:

https://www.avsforum.com/threads/polk-audio-vt60.3138706/

The sonance enclosure is made from 1/2" MDF and screws between the studs IIRC.

Klipsch provides almost zero information on their 5650 speaker:

CDT-5650-C II In Ceiling Speaker | Klipsch

The Klipsch CDT-5650-C II in-ceiling speaker meets the market's demand for a high-performance in-ceiling loudspeaker.

www.klipsch.com

I've searched and not found anyone else who has built a backbox for these speakers. Any help is much appreciated!

 

[FriedChicken]

Klipsch support told me I want a 2.5-2.8 cu. ft. backbox

 

[FriedChicken]

I decided against a backbox for two reasons:
1. the ttic upstairs serves as an infinite baffle,
2. the work involved would (I would have had to extend two romex cables with 2 junction boxes for each extension).