For folks who need a "thin" profile subwoofer, the
Velodyne SC-600 IF/IC may be an option.
It measures 32" high by 14" wide, but only 9" deep, and it sports a ported 12" woofer w/ protective metal grille. It is made for in-floor or in-ceiling iinstallation. But because of the thin profile, it could also be placed behind other things.
It is non-powered, so you would need an external amp. The SC-600 is 4 ohms nominal.
I bought 4 of these subs (all on sale, of course
). All four fit behind my 73" DLP TV, which sits on a simple wood TV stand that I bought from Walmart for $100. You would NOT immediately notice the 4 Velodyne since they are hidden behind the TV.
I have an old OSD amp which is like 225wpc x 2ch 4 ohms. It has A/B speaker selection (4 subs can be connected). Pressing both A & B powers all four subs (2 Left, 2 Right).
2 Velodyne for the P362 (karaoke), and 2 Velodyne for the Phil3 (music).
These SC-600 subs can pack a punch. They only go down to 25Hz @ -3dB per spec, but compared to the BIC PL-200 they replaced, these velodyne seem a lot tighter. And they can shake and rattle the walls for sure in my 18' x 20' living room. Whereas the BIC PL200 seem a little boomy, the SC-600 seem more damped and controlled (smaller Q-value).
I really like these Velodyne SC-600 for their sound quality and for their 9" thin/ flat profile.
