Subwoofer insight.

In my experience and in my opinion....  

An 8 inch subwoofer in a 28' x 38' x 9' room?   I don't think so.  It's all about moving air. A single 8" driver can't move enough air.   2 x 8" drivers can't move enough air.  8 x 8" drivers can't move enough air.    

I use 2 x 18" subs in a room 14' x 26' x 8 1/2' and have them properly corner-loaded.  And I'm thinking of going to 4 x 18".   They are Eminence Kilomax Pro-18A drivers.  Bullet-proof.  

For your room, I would suggest 4 x 21" drivers and use them below 30hz.  If you want subs to go higher, then consider 8 x 15" (4 per side) using VERY STEEP low-pass filter at 45hz.  32hz / octave is the minimum low-pass slope, the steeper the better.   The object is to keep the anything over 60hz off the sub drivers.  It will cause transient time smear and other problems.  

I'm a REL S5 SHO owner. You can't go wrong with REL as long as you match correctly to your mains and room size. IMO the T series is a bit smallish for your room size. I think a stereo pair of the 812se is probably more what your room size needs. Call REL directly and they will help you match to the right sub in their lineup. 

GLHF!

I had a pair of T7i’s with my Dynaudioo Contour 60’s in a much smaller room. They really expanded the sound stage and the overall sound. Just upgraded to a pair of REL S510’s. Another big jump in SQ and now they really dig deep. I would recommend the 510’s or the 812’s for a room that big. 

When it comes to two channel music, nothing in my opinion rivals REL subs. For your room size, you need to go with a pair of S5 or newer S/812.

I switched from JL audio to REL Carbon Limited and couldn’t be any happier. You can always send an email to REL support and they will reply with best recommendation based on your main speakers.

support@relsupport.zendesk.com

using different speaker taps directly to mains and directly to subs denies a fundamental advantage of self-powered subs. the need for bass comes from the source, the main amp will still be trying to make/send all bass, the main speakers will still be trying to make all bass.

you want to remove low bass signals going to both the main amp and main speakers, especially inefficient and range limited mains, like yours. then they both can do a better job.

preamp out to crossover, or preamp to sub with adjustable crossover, self powered subs,

then signal less low bass back to main amp or integrated amp line in. main amp now doesn’t need to deal with low bass signals. low bass signals no longer seen by inefficient main speakers, those speakers no longer ’try’ to make low bass.

ideally easy ability to adjust sub’s crossover and adjust subs volume. this has to be done while they are in their intended location, again, bass is not always mono, so I advocate a pair of front firing subs near the mains. if hard to access controls, and heavy, put them on low rolling ..., pull out, adjust, slide back in place, listen.

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