I ordered a set of 2 tri-traps and a diffusor for my smallish loft room, which overlooks my living room. Team GIK on this site recommended the tri-traps and diffusor after chatting about my room. I also stumbled into a pair of Elite Pillar Bass Traps that my local dealer wasn't using after he remodeled his room with other GIK products.
Prior to getting the room treatments, I had the use of a high-quality room setup mike and set of test CDs, which revealed a very clean treble, but also 3 moderate-to-severe dips in the region from 100-300 hz. A waterfall showed some delay problems in the lower bass, especially from the left speaker. The room supports the lowest frequencies because of its access to the larger room underneath it.
I got the Elite Pillars a couple days before the tri-traps, so I installed those behind my speakers. They are quite attractive, and match the wood on my speakers (Harbeth Compact 7ES). I had THOUGHT that the speakers suffered from midrange congestion on larger orchestral works; beyond the normal limitations of a mid-sized standmount. Turns out that the bass clutter from behind the left speaker was the culprit. The placement of the first bass pillar provided a much cleaner mid-bass (well above the problem area shown in the waterfall plot). Ray Brown's plucked thirds now show clearly as distinct notes, and the horns in the Bruckner 9 are cleaner-edged but retain their appropriate weight and "blat."
When I got the remaining GIK gear I experimented with the diffusor and tri-traps, eventually placing the diffusor on the first reflection of the left speaker (which otherwise is a draped window), as GIK had recommended.
The tri-traps went in the corners behind the listening chair.
With this setup the soundstage expanded to the left, which eliminated a right-channel bias which was probably a result of the differences between the two surfaces; one a window, one a wall painted with sand-based paint. I would term this an important development.
I also got a bit more soundstage depth. This is a weakness of my room, so I'm happy with even a minor improvement.
In summary, the combined products yielded major improvements in lower bass clarity and impact, major improvement in mid-bass clarity, signficant improvment in soundstage width, and a minor improvement in soundstage depth. I don't hear much change in the treble, which was outstanding (+/- 1 db) to begin with.
To give some perspective, I would consider the soundstage depth improvement to be on a par with, say, getting better cabling. The bass improvements are on a level with getting new speakers. At least 50% of the overall positive impact came with the placement of the single bass pillar behind the left speaker.
The net result is that my speakers will NOT be for sale, and I'm going to continue to experiment with room treatment placement, after I remove my LP and CD storage units from the room.
Background: Dedicated 11x12 listening room opening via a 47-inch high wall to a great room, with no obstuctions between speakers and listening site. My speakers are placed following the guidelines in Getting Better Sound, confirmed by measurements and listening, at 80 inches apart, 96-100 inches to the listening chair, toed in to meet about a foot behind my head. REL sub running at about 55 hz cross over, 0 phase setting, speakers running full range. Luxman 505u, Marantz 8004. Listening preferences are classical from chamber to Mahler and Bruckner, opera, and jazz. And the Clash.
