Best type of Sub to consider?

It seems to me that the answer may depend on where you would want to place the sub(s), which in turn may depend on how much of the bass region you want to augment. And given that all of the woofers in your speakers apparently fire mainly toward the rear, and that essentially half of the area that they are firing toward is non-reflective open space, I suspect that you would want the augmentation to extend relatively high in frequency (e.g., perhaps even upwards of 100 Hz).

If so, I see only two placement possibilities that might make sense, both requiring two subs.

One would be to place a sub alongside the inner surface of each speaker, firing toward the wall just as the woofers in the speakers do. (I presume placing subs alongside the outer surface of the speakers would be unacceptable because it would impede traffic, and perhaps also for aesthetic reasons). Although I would have some concern about the vibrational effects that placement might have on your turntable and electronics.

The other possibility would be to place the subs against the wall, one at its left end and one at its right end, with them firing forward. Ideally the subs would be chosen to provide a means of introducing a variable delay of a few milliseconds into their outputs, so that their outputs could be time aligned with the wall reflections corresponding to the outputs of the woofers in the main speakers.

For either of those placements, and if my suspicion is correct that you would want to augment up to relatively high frequencies within the bass region, it seems to me that two front-firing subs would be the way to go.

Good luck. Regards,
-- Al

Al,
Thank you for your informative answer, because that's what I was looking for. I did speak to a sub manufacturer, who recommended that I place two subs behind my speakers about four inches from the walls. These subs fired down, and it made me wonder how this would differ and/or be an advantage, or not, over a forward firing design. In my mind, a forward firing design may help to take out the need to rely so much on closed corners. However, I must admit that my study of speaker design and sound wave physics is truly limited. My ears are everything, but as we know you cannot sample everything. I appreciate you wishing me luck, but I will do my best not to rely on that. Thanks again.
Kenny

ricred1 and gdnrbob,
Thanks. I have only been looking at sealed subs, and even in that category, there are all these different types. So, why I posted.

Dan,
Yes, I completely read your comments about your success with your Tannoys and Crown, so thank you. You're right, here I go again finding my way around.

I really love my Hsu Research ULS-15 Mk II sealed subwoofer.  It works very well with my listening, as well as with movies.  Here's  link to my review on the sub:

http://http//www.ayllonmedia.com/1/post/2015/10/does-the-hsu-fit-a-look-at-the-uls-15-mk2-subwoofer.html

Good luck,


Juan 

I greatly prefer the sealed over ported subs in almost all cases. I like the JL audio subs alot, after them the RELs.  The REL hookup procedure is nice if you dont have the outputs on your preamp, or dont want to purchase extra cables. In my experience subs have have improved soundstage presentation in every system I've had them in. Good luck