- Written by Tyler Stripko
- Published on 28 May 2013
Setup of the Polk LSiM System
I initially placed the 707 towers with their rear baffle about two feet from my back wall and three feet from the sidewalls. Initial frequency response sweeps with my newly acquired XTZ Room Analyzer II Pro kit (review forthcoming) showed that this was a less than ideal position. I was getting a lot of bass bloat below 125 Hz and some pretty significant dips around 200 Hz. Moving the speakers until they were about 4.5 feet from the back wall improved bass response, but I was still left with almost 6dB of excess bass energy centered around 50Hz and 100Hz. Moving the speakers two feet further away from the side walls improved the mid-bass and midrange response a bit further but I had extra bass energy, even after I moved my listening seat about 18 inches further back in the room. A quick test with the speakers another two feet further from the back wall showed that I could trim the excess bass, but it would have put the speakers in an unacceptable position if I wished to keep my marriage intact.
With my slightly bass-compromised speaker position now set, I turned my attention towards toe-in. Using some test tracks, I settled on aiming the 707s so that they converged on a point roughly four feet behind my head. This seemed to give the best stereo imaging while also giving me the deepest soundstage. Take a look at the screen shot below, which shows the in-room frequency response of the left front 707 tower in its original position (blue trace) as compared to the final, slightly compromised position denoted by the green trace. While you can still see the peaks in the bass and a small dip in the upper bass, take closer note of the extremely smooth response from 200Hz on up. Also look at the bass response. At 25Hz the 707s were only down about 2.5dB from the reference level. A subwoofer truly is optional with these bad boys. However, you may be able to get smoother overall bass response with an external sub (or two) depending upon your room's acoustics.
The 706c center channel was placed atop my Salamander Triple 20 TV cabinet using the included rubber stick-on feet. This position kept the rear port of the speaker about 2.5 feet from the back wall, which unfortunately was not far enough out to eliminate all bass bloat. I quick response sweep with the 706c on a box further out into the room proved that my positioning was the cause of the added bass bloat, not the speaker itself. The frequency response of the 706c center channel mirrored the 707 towers closely with bass response rolling off at an impressive 40Hz. I initially used the 703 bookshelves as my side surrounds, placing them on a pair of stands ten feet to the sides and slightly behind my primary listening seat. The 703s also exhibited very smooth frequency response and had solid bass output into the low 40Hz range. The F/X 702s don't have quite the muscle of the 703s, and rolled off bass below 60Hz. I mounted the F/X 702s on stands placed against my back walls to use as rear surrounds.
If you choose to wall mount the 702s it is very easy to do thanks to the included installation template. The F/X 702s include a switch that changes the bass response of the speaker for on/near wall installation (like I used) or when the speaker is more than two feet from a wall. Once everything was in place I ran a full Audyssey Pro calibration on my Integra DHC-9.9 pre/pro to dial in levels and distances. Unless specifically mentioned, all of my listening notes describe the sound with all forms of Audyssey correction off. The remainder of my connected gear included an Oppo BDP-83SE NuForce Edition Blu-ray player and Xbox 360. Amplification was provided by my Wyred 4 Sound 7-channel amplifier, 3 x 550 watts for the front channels, 4 x 250 watts for the 4 surround channels. My Hsu VTF-3 MkII provided the LFE.