EDIT 10/04/2018: See post #13 below for some minor design changes lowering net volume from 6.7 c.f. to ~6.1 c.f. and the rationale for same. Post #14 contains some pictures from construction and discussion about methods used.
Recently I started a thread looking for t/s parameters for a driver I had salvaged from an old Velodyne VRP-1200 along with the original plate amp. The enclosure had sustained some superficial water damage, which did not harm the driver or amp. My goal is to create an inexpensive sub for use in a second listening area of our house where we mostly listen to music at low or medium volume. There is no HT use in this space as there is no TV, and if I want to watch movies or listen at full volume, I can do so downstairs where I have a ~7CF cabinet with an RSS390HF-4 hooked up to an iNuke1000DSP.
A helpful soul in that thread suggested I might do better to look at buying a JBL CS1214 / CX1200 as a replacement, since parameters for that driver are available and the driver comes at no great expense.
After studying the JBL driver and thinking how best to use it with the other odds & ends I have on-hand, I've come up with a design for a large-ish slot-ported enclosure using the plate amp from the Velo (specs say 135w RMS). I'd appreciate if you guys would have a look at the attached photos and chip in with any thoughts or concerns that come to mind. I'm also still thinking about a few design considerations and would appreciate any input you might have regarding the following:
1. These dimensions mostly come from looking at where I can fit this into my listening area without seeking a long-form review from the wife. I can make it taller or shorter without much trouble (the height shown is based on the max possible to build this cabinet from one 4' x 8' sheet of 3/4 MDF), but width and depth are following adjacent furniture pieces. Do the design and model look sane? Am I missing anything big?
2. I'm showing this as a down-firing configuration. I realize that I could move the driver to either side or the front, but we have a dog, a two-year-old boy, and another baby on-the-way. You can understand why a hidden driver would be desirable in a family household. Are these drivers known to do well or poorly in this application? Can anyone comment on a reasonable height to elevate the cabinet above a short-pile carpet using spikes or feet? Would spikes or feet be better on a plywood-over-joist subfloor on the 2nd level of our open-concept home?
3. I'm showing a 2nd order high-pass Butterworth filter at 20hz which solves problems with both port air velocity below 21hz and with cone excursion below 18hz. I have an FMOD High-pass 20hz laying around. Do I understand correctly that putting it into the signal-path will provide the modeled 2nd order modification (they are advertised as 12db/octave)?
4. Further, regarding question above about using an FMOD - any chance that the plate amp from the Velo would have an SSF built-in?
Would anyone here know for sure? Could I tell by looking at the circuit layout of the amp? Would it hurt anything to compound the attenuation by using the FMOD together on-top-of a SSF built-in with the amp?
5. This cabinet would replace a half-height bookcase on top of which my receiver currently rests. At the low SPL/power that I'm proposing, is it safe to assume that for mid to low volume level use for mostly music, that this cabinet would not be likely to shake that receiver to death?
Again, given the low-power application, how much bracing do I need beyond the included shelf forming the slot-port?
I've ordered a driver and expect it to come later this week - I'm looking forward to getting the build started and promise that I'll share pictures of my progress. Thanks in advance for reading and for any input you can provide!