CDT 5800 C II installation advice

[saebel]

Hello folks.  So I've bought the speakers (six of them), have the wire, have the tools to cut the holes.  Before jump to it, I have a couple of concerns and was hoping other folks out there have figured out how to solve these issues.

 

My house was built in 1911 and has a large attic space.  Joists are 16" on center.  Ceiling is wooden lathe and plaster with drywall/sheet rock below.  Obviously not new construction.  Now maybe the lathe and plaster is strong enough to hold each speaker?  Maybe?  They are definitely much heavier than I expected and I'm concerned about sagging.

 

I am also concerned about containment.  The attic space has got insulation all over and is wide open.  Did a wee bit of research and came up with three possible solutions:

Option 1: Bag it: https://www.parts-express.com/pro-wire-isf-147-insu-flate-ceiling-speaker-protector--300-265

Option 2: Box it: https://www.klipsch.com/products/me-800-c-speaker-enclosure

Option 3: Foam it: https://www.amazon.com/Install-Bay-Universal-Speaker-Acoustic/dp/B00L8FDPLW?ref_=fsclp_pl_dp_13

Option 1 seems like a simple solution for protecting the speakers from the attic dust, etc., but doesn't address potential issues with bearing weight over time.

Option 2 has had a very positive response from those who installed them.  However, from every description I have read, it appears they were meant to be installed during construction pre-ceiling install and attached directly to the joists from below.  The holes on the flanges are 16" on center.  That makes them problematic because I don't know how we would fit them in unless we cut out the entire sheet rock, install them, and then put the sheet rock back.  Here's a link to the spec sheet: http://images.klipsch.com/ME800C_635042118497170000.pdf

Option 3 looks like it might handle the protection element (assuming they fit, it's really hard to tell), but won't address the potential issues with bearing weight over time.

[saebel]

I think I have it figured out:
1. use 3/8 inch plywood, cut into 14" x 18" rectangles (to fit between the 16" joists).

2. Cut the hole in the center of the plywood for the speaker to fit through it.

3. Cut the hole in the ceiling.

4. Line up the plywood hole with the ceiling hole and attache to joists with L-brackets.

5. Take the ME-800-C enclosures and cut off the extra metal trim on the sides so that you end up with a 13.5"ish x 17"ish frame.

6. Attach the ME-800-C enclosure to the plywood plate via duct tape (since the trim with holes will have been removed).

7. Mount the speaker to the enclosure/plate.

 

I think I'm just going to buy one for now and see how if my theory works.  If it does, I will buy the rest.

Edited July 3, 2020 by saebel
Got the specs wrong. Corrected how to trim/cut it.