Stereo Subwoofer Pairing

I use 2 differing REL models from the same era (Q150e, Q108 MKII) wired together getting their signal from the main tube amp. With bass I've found that the tone indicating where a bass is in the mix comes from whatever higher frequency overtones (or simply tones) are there so they're basically mono in their low range duties. 2 subs work better though to smooth out room nodes as perceived from the listening spot, with one sub (the larger Q150) right behind the left speaker, and the other against the right wall so I can stick it in a window for deck listening (with a couple of monitors also stuck in the windows powered by another amp). I agree that keeping the RELs lower (but properly matched to the mains) with higher gain works best. 

The Antimode engineers recommend corner placement for maximum reinforcement and minimal dips/nulls. That position unfortunately also gives the biggest peaks, but you can deal with those with the room eq.

" The Antimode engineers recommend corner placement for maximum reinforcement and minimal dips/nulls. That position unfortunately also gives the biggest peaks, but you can deal with those with the room eq."

Hi willemj,
     
     Yes, I've found that corner placement of subs results in the most bass due to the long bass sound waves reflecting off of both walls in a corner. This often results in bass peaks (exaggerated bass) at spots in the room. That's why I advised against it although some may like it.
     I've found avoiding placing subs in the corner results in more accurate and natural bass response which I prefer.
    I remember you mentioning your Antimode DSP room eq unit before .  I  use zero DSP, eq and bass room treatments in my room since I haven't found a need to since employing the 4 sub system. It's almost magical how this system eliminates bass nodes in the room and just provides accurate, natural and, when the source calls for it, very deep  and powerful bass on both music and ht.  
               

I plant to try one of my subs in the bay window area behind my listening sofa.  On one hand there isn't tons of room back there - a space about 8 feet by 3 feet deep.  On one hand I imagine bass frequencies "building up" in that space.  On the other, the sub would be between the bay windows and a massive custom sofa that spans the whole room width, and I'd think this would also provide some "trapping" as well.  I'm not sure how what to expect, but the other subwoofer will be on my front all behind my speakers, to the right, so the subs will end up on a roughly "diagonal room placement" which apparently is one that can work out well.

I hope.

As promised, here is Rel's response about using the T and the T/i models together:

With careful tuning using the rear panel controls, it's very possible to tune in a T/I with an older T. Just remember that the T/I will sound much faster and more lear/forceful down low so it will be down to careful placement and tuning but, yes, with little good judgement, you should be able to pull them together into a very good result.

Because room acoustics take precedence I can't give you a "turn this knob to this setting" sort of cookbook set-up. Just take it slowly--get the first unit dialed-in to its speaker, then unplug the Speakon and do the same for the other side. Then it will just be down to turning the volume on each REL down util the combined gain is right since the subs will be a little hot once both RELs are plugged back in.

Thanks for the question!