Polk LSiM Home Theater Speaker System

Best of 2013 Awards

Introduction to the Polk LSiM Home Theater Speaker System

Since being introduced about 10 years ago, the Polk LSi series of speakers was one of the first lines I’d recommend to people who cared about sound but didn’t want to break the bank. With performance that was well above their price class and numerous models, the LSi series could be configured to meet the needs of just about anyone or any room. Fast forward to 2012 and we have a new from-the-ground-up version of the LSi: the LSiM. Starting from a blank slate, Polk has released six new models, four of which are on hand for this review. To see if the new LSiM series speakers could live up to the high standards of its predecessors, I requested a full surround setup for my large media room.


LSiM 707

  • Design: 4-way Tower, Sealed (Mid Array) and Ported (Woofers)
  • Drivers: 1 x 1″ Ring Radiator Tweeter, 1 x 3.25″ Midrange, 1 x 6.5″ Mid/Woofer, 2 x 6″ x 9″ Woofers
  • MFR:  30 Hz – 38 kHz, – 3 dB
  • Nominal Impedance:  8 Ohms
  • Crossover Frequencies: 3 kHz, 300 Hz, 100 Hz
  • Sensitivity:  88 dB
  • Recommended Amplifier Power: 20-300 Watts
  • Dimensions: 50.2″ H x 10.5″ W x 20.3″ D
  • Weight:  99.2 Pounds/each
  • Standard Finishes: Midnight Mahogany or Mt. Vernon Cherry Real Wood Veneer
  • Warranty:  5 Years
  • MSRP: $1,999.95/each USD

LSiM 706c

  • Design: 3-way Center Channel, Sealed (Mid Array) and Ported (Woofers)
  • Drivers: 1 x 1″ Ring Radiator Tweeter, 1 x 3.25″ Midrange, 2 x 6.5″ Mid/Woofers
  • MFR:  50 Hz – 30 kHz, – 3 dB
  • Nominal Impedance:  8 Ohms
  • Crossover Frequencies: 2.8 kHz, 280 Hz
  • Sensitivity:  88 dB
  • Recommended Amplifier Power: 20-250 Watts
  • Dimensions: 9″ H x 28.75″ W x 13.8″ D
  • Weight:  42.3 Pounds
  • Standard Finishes: Midnight Mahogany or Mt. Vernon Cherry Real Wood Veneer
  • Warranty:  5 Years
  • MSRP: $1,199.95 USD

LSiM 703

  • Design: 3-way Bookshelf, Sealed (Mid Array) and Ported (Woofer)
  • Drivers: 1 x 1″ Ring Radiator Tweeter, 1 x 3.25″ Midrange, 1 x 6.5″ Mid/Woofer
  • MFR:  50 Hz – 30 kHz, – 3 dB
  • Nominal Impedance:  8 Ohms
  • Crossover Frequencies: 2.8 kHz, 280 Hz
  • Sensitivity:  88 dB
  • Recommended Amplifier Power: 20-250 Watts
  • Dimensions: 16.75″ H x 8.7″ W x 14.8″ D
  • Weight:  29.6 Pounds/each
  • Standard Finishes: Midnight Mahogany or Mt. Vernon Cherry Real Wood Veneer
  • Warranty:  5 Years
  • MSRP: $749.95/each USD

LSiM 702F/X

  • Design: 3-way Surround, Sealed (Mid Array) and Ported (Woofer)
  • Drivers: 1 x 1″ Ring Radiator Tweeter, 1 x 3.25″ Midrange, 1 x 6.5″ Mid/Woofer
  • MFR: 55 Hz – 30 kHz, – 3 dB
  • Nominal Impedance:  8 Ohms
  • Crossover Frequencies: 2.4 kHz, 240 Hz
  • Sensitivity:  88 dB
  • Recommended Amplifier Power: 20-200 Watts
  • Dimensions: 16.25″ H x 19.9″ W x 6.75″ D
  • Weight:  28.9 Pounds/each
  • Standard Finish: Black Gloss
  • Warranty: 5 Years
  • MSRP: $1,499.95/pair USD
  • Polk Audio
  • SECRETS Tags: Polk Audio, Speakers, Home Theater, Audio


Design of the Polk LSiM Home Theater Speaker System

The media room in my home measures approximately 23′ X 26′ with a 7.5′ ceiling height. This puts the approximately 4500 cubic foot space firmly into the “large room” category. As such, I built this setup around the largest speaker in the LSiM line, the LSiM 707 tower. Weighing in at 99.2 pounds and standing 50-13/16″ tall, the 707 is not for the feint hearted. This speaker will definitely draw attention to itself due to its commanding presence. For center channel duty, I chose the LSiM 706c. This is the larger of two available center channels and its drivers match up well with the 707 tower. For surround duty, I requested both the LSiM 703 bookshelf speaker as well as the LSiM 702F/X dedicated surround-channel speaker so that I could compare a direct-radiating speaker to something more diffuse for the surround channels.

Befitting their all-new design, there are a ton of new features common to all models in the LSiM range. First is the “Dynamic Sonic Engine,” Polk’s term for the molded enclosure that isolates the tweeter and midrange driver in their own separate molded enclosures. Each of these enclosures is tuned for their resident driver, resulting in increased dispersion, better imaging, improved detail retrieval, and better off-axis response. Next, Polk took the ring-radiator tweeter from the LSi series and enhanced it, resulting in increased power handling, more extension (to a claimed 40kHz), and better dispersion. The midrange/woofer drivers are now made of “Super Cell Aerated Polypropylene,” which is said to offer a nearly ideal combination of weight versus stiffness. The subwoofer drivers in the LSiM 707 and LSiM 705 tower are a completely new “Cassini Oval” design. This is Polk’s take on the oval “racetrack” shape that has been used by other companies over the years. The oval shape increases the overall surface area of the driver (key to moving enough air for deep bass response) without dramatically increasing the overall width of the speaker. Used in combination with Polk’s trademarked PowerPort® bass venting, the new bass drivers generate more powerful bass without additional distortion or port noise. Extended Linear Motion (ELM) voice coils combined with cast aluminum baskets further contribute to improved power handling and output levels. Polk’s proprietary “Orth” crossovers (named for one of Polk’s Systems Engineers) mate the drivers to one another as well as level out the impedance curve.

Cabinet construction has also taken a huge step forward in the LSiM series. The sides are now 1″ MDF and are curved to reduce standing waves and internal resonance. Back and bottom panels are ¾” MDF while the front baffle is 1-1/4″ MDF. To further improve efficiency and reduce resonance, each driver is housed in its own chamber within the main cabinet. The standard “knuckle test” produced a very solid “thunk” on all of the LSiM speakers with one exception. Knocking on the lower portion of the LSiM 707 towers where the bass drivers reside did result in a bit of perceived resonance, with a slight hollow ringing that was detectable to my ears. Other than that, the overall construction quality of all of the LSiM speakers really impressed me. From the hefty feeling dual 5-way binding posts to the excellent “hex-head floor spikes” on the 707s, I was really impressed with the build quality on these speakers. I want to go back to “hex-head floor spikes” for a moment. Instead of having to lift the big speaker and fiddle with spikes that adjust from underneath, you simply insert the included hex-head wrench and turn. I know that other manufactures have used similar systems in the past, but why this hasn’t become the industry standard is beyond me as they are just so easy to use. Out of the box, these spikes are covered with rubber feet to protect wood floors but you just pull off the feet to access the spikes.

All of the speakers except the F/X surrounds can be covered in one of two real-wood veneers: Mt. Vernon Cherry or Midnight Mahogany. The F/X surrounds come only in a black gloss finish. The two wood veneers have a satin varnish, which helps cut down on reflections in a darkened room. As I watch all of my movies in a blacked out environment I really appreciate non-glossy speakers, particularly the center channel as it sits directly beneath my display. Regardless of color, the overall fit and finish of the veneer is excellent. I couldn’t detect a single seam on any of my speakers and many visitors to my home couldn’t believe that they were looking at a Polk speaker. They all thought it was something far more exotic. It’s pretty amazing how far Chinese manufacturing has come. I also liked the contrast offered by the gloss black front baffle against the wood veneer. Invisible magnets are used to attach the “zero diffraction” speaker grilles to each speaker. The grilles felt a bit flimsy to me, but attached securely and were very easy to remove.


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.


The Polk LSiM Home Theater Speaker System In Use

With all the speakers positioned, I ran the LSiM system for about a week before doing any critical listening. Since I had already run through most of my standard test tracks during the setup period, I started my listening sessions with some newer 2-channel material to get a feel for the big 707 towers. Diana Krall’s latest album, “Glad Rag Doll,” hasn’t been met with the same critical acclaim as her earlier works but I like it nonetheless. While a bit of a departure from her prior albums, I really dig the sultry jazz mixed with a bit of blues that she went for. Track 11, “Lonely Avenue” is probably my favorite on this disc. It’s got a sweet bass groove, nice guitar work, and solid vocals. Unfortunately, this song is also one of the numerous tracks on the disc that was intentionally “aged” in an effort to make it sound like it was recorded 50 years ago. They added lots of hiss and grain in post-production which unfortunately added a layer of haze to many of the songs on this album. While I understand that this was an effort to fit in with the whole “rag” theme it’s my biggest gripe with the CD and a huge detractor from what could have been some amazing sound quality. However, there are still some great sonic moments here.

Through the 707s, the bass line was incredibly easy to follow, with excellent definition between bass notes. Even with the bit of extra energy present in the bass, each individual drum hit was crisp and sharp, with great decay of every note. The slide guitar was clean and clear with the proper amount of “sadness” to each note. The overdriven electric guitar was perfectly sweet sounding and fit in well with Krall’s silky-smooth voice. Overall, the midrange sounded just right: not too sweet but not too harsh. Krall’s lyrics were crisp without any added sibilance or etch. On the tracks that were “aged” in the studio like “Lonely Avenue” the extra hiss, crackle, and distortion that was added in post-production was blatantly obvious.

As a huge ZZ Top fan, I naturally picked up their latest effort, “La Futura.” I was particularly curious to see the impact Rick Rubin’s production style would have on “that little old band from Texas.” Style wise, this disc seems to combine a bit of ZZ’s style from the late 1970’s with their more modern blues/rock sound from recent albums like “XXX” and “Antenna.” While some old riff lines have been recycled, almost every song on this disc is well crafted. The hook lines are catchy, the guitars are in-your-face-powerful, and Billy Gibbons’ cigarette-raspy voice sounded great. The 707’s were able to capture this visceral power while still allowing me to hear the subtlety of Gibbon’s picking and Dusty Hill’s bass lines through their overdriven Crate amps. Frank Beard’s drum kit was deep, crisp, and very well controlled with cymbal crashes having a nice amount of sizzle and air. The clarity and dynamics of this disc really startled me, as I’m not used to hearing such a pristine rock recording. I hope Rick Rubin sticks with ZZ Top for their next project.

Melody Gardot’s newest release, “The Absence,” differs from her prior works in that it takes a decidedly Brazilian slant. I like the change and this disc sounds just as good as her more jazzy prior works. The bells and chimes during the introduction of “Lisboa” sounded absolutely stunning, sparkling across the soundstage. When Gardot’s voice comes into play, the sound was truly wonderful. Each subtle nuance of her very expressive voice was easy to ascertain, and really shows a listener what a gifted vocalist she is. The 707s really let her voice shine, as they are very neutral throughout the midrange, with just a touch (and I mean a touch) of extra warmth to make most recordings sound even more musical. “Impossible Love” is my favorite cut on this disc and sounded absolutely fantastic. It has some very powerful dynamics, with Gardot’s voice dancing through the track to the compliment of powerful strings, Spanish guitar, and assorted percussion instruments. The bass line had tremendous power, and combined with the stringed instruments just seemed to jump out at me from the speakers. In an age where every song seems to be redlined against the peak limiter, it is refreshing to hear music with such a wonderfully natural range.

With it now obvious that the 707 towers were excellent, it was time to hear the system as a whole. In went my cherished DVD-Audio disc of The Talking Heads “Speaking in Tongues.” Track 11 is an alternate version of their hit “Burning Down the House” and is also one of the greatest examples of surround music that I’ve ever heard. Within about 30 seconds I knew that the Polk system was something special. The overall sense of space and ambience was excellent. The sound moved seamlessly from speaker to speaker, with absolutely no disparity of tone or timbre as sound moved from channel to channel. The big 706c center kept the vocals centered beautifully, but blended perfectly with the 707 towers when the sound moved out from the center channel, which happens frequently on this track. The 703 surrounds mated just as well with the rest of the system, which only further enhanced the immersive effect of the music. This is a particularly active surround mix, with the multi-layered effects bouncing from channel to channel. The LSiM system handled the rapid movement better than any system I’ve heard in my room. Bass was very deep with tremendous impact and I found myself inching the volume up higher and higher, reveling in the incredibly clarity of the high-resolution mix. What is even more amazing is that even at incredibly high volume levels (over 100dB), there was absolutely no distortion or sense of strain. All of the speakers remained smooth and clear, without the upper midrange/treble harshness that many other systems can exhibit when driven hard. I’ll give some of the credit to my extremely powerful Wyred 4 Sound amp, but equal credit must be given to the Polks. Don’t be afraid to match these speakers with a big amp, as they can clearly handle it.

“Britten’s Orchestra” is another example of surround sound done right. The intro track, “The Young Person’s Guide to the Orchestra” is a fantastic test of any speaker system. This composition runs the gamut of just about every instrument used by a full orchestra and gives a bit of a spotlight to each orchestra section throughout the 17 minute 9 second runtime. I wound up sitting through the entire track, enjoying each passage immensely. The Polk system did so much right that it was hard to find fault. The bass was full, punchy, and accurate with each powerful tympani hit fluttering and decaying naturally into the background. Brass was appropriately bright, but never harsh or grating. The strings were beautifully clear, with a real sense of body to individual instruments. Woodwinds struck the proper tone to my ears, being light and airy without becoming screechy. The only minor chink in the Polk system’s armor was in cymbals and bells. While these instruments sounded very good, they were lacking a bit of air and sense of reverberation compared the best speakers I’ve heard. Also, imaging and soundstaging were not reference level. While I could get a good sense of where the instruments were on the stage, I didn’t get the pinpoint sense of imaging I’ve heard with other (all more expensive) speakers. The system seemed to present a decent sense of depth, but kept the sound compressed over a narrower width than I have heard on some higher-end systems.

We hosted a dinner party for my wife’s family one evening and as always, the men wanted to see what type of goodies I had in for review. In went the DVD-Audio disc of the Beatles “Love.” What was supposed to be a 5-minute demo turned into a screening of the entire disc, with all of our guests (including the ladies) taking a seat to listen. My audience was completely mesmerized for well over an hour. Four of these guests had actually seen the Beatles live in the 60’s and early 70’s so I was particularly interested in what they thought. “It sounds like Paul is right in the room” was probably my favorite comment. While the LSiM system couldn’t do much to tame a few of the harsher tracks on this disc, it really shined on the better ones like “Blackbird/Yesterday” and “While My Guitar Gently Weeps,” which actually drew applause from my crowd. My wife’s uncle was in attendance that night and he owns a full surround system based around Polk’s original LSi15 towers (as well as a dedicated 2-channel system with B+W Nautilus 802s). Most likely, he will be upgrading his theater room to an LSiM system soon.

After such a great experience with music, I fully expected to enjoy the LSiM system for movie watching. I was not disappointed. Knowing that the LSiM system was capable of delivering some big sound, I started out by watching “Transformers: Dark of the Moon.” While one can debate the quality of the plot, there is no debate on the quality of the audio. The 7.1 Dolby TrueHD was incredible, from the opening credits through the final end battle. I could hear all of the mechanical “transforming” effects as each robot went from its alternate mode to robot form in perfect clarity. Vocals rang true from the 706c center channel and the surround channels carried ambient effects with perfectly matching timbre and tone.

While the LSiM system could clearly deliver the biggest of soundtracks, it was its prowess with more subtle fare that really impressed me. The introductory scene of “Master and Commander: The Far Side of the World” is a study in the effective use of surround sound. The creaks and pops of the ship below decks, the wind passing through rigging and sail, and the lapping of the waves against the hull resonated through every speaker with absolute believability. When the peace and quiet ends with the first fight against the Acheron, the sounds of battle envelops you. Cannon shots splinter the wood of the Surprise and zing through the surround channels. Bass from the cannons was deep and forceful, while remaining tight and crisp. The sounds of the wounded sailors emanate from the surround channels with haunting effect. It all makes for one heck of an audio experience.

I finally got around to watching my Blu-ray copy of “Star Wars: Return of the Jedi” while I had the LSiM system in my possession. While I have heard the old Dolby Digital mix from the DVD dozens (if not hundreds) of times, the new DTS-HD Master Audio track was a revelation. The clarity and smoothness of the lossless audio is in a whole different league from the DVD’s compressed signal. The 706c center channel continued to impress me with its perfectly matched performance with the 707 towers. Dialogue was much clearer than I remember, without sounding over-boosted. Background noises in Jabba’s palace that I never heard before were now apparent. Ambient effects in the forests of Endor experienced a similar increase in clarity. However, what impressed me the most was how stunning the score sounded. A prime example was the Ewok theme that plays during the end credits. The theme uses what sounds like a xylophone in parts. Those notes rang with a clarity that I’ve never before experienced and decayed ever so naturally into the background.

I received my copy of Metallica’s latest concert Blu-ray, “Quebec Magnetic” right as I was preparing to pack up the LSiM system. While I loved the last Blu-ray concert from the band, “Orgullo, Pasion, y Gloria” for its incredible energy and performance, I have always harbored the feeling that they applied a bit too much post-processing to the sound on that disc. “Quebec Magnetic” is noticeably closer to what you would hear at a live Metallica show. James Hetfield’s vocals were raw and off-key. The guitars of Hetfield and Kirk Hammett had increased clarity and a bit more bite to their initial attack, just like in real life. I was able to hear their fingers sliding from note to note, which is pretty impressive on a live mix. Bass guitar from Robert Trujillo and the drums of Lars Ulrich were viscerally powerful yet not over-boosted as is typical on most concert discs. I’ve seen this band perform 8 times now, and “Quebec Magnetic” is the closest thing I’ve heard to a live show. The set list was one of the best as well, with a few songs not typically performed live turning up. I broke 110dB on the LSiM system when playing this back and not once did the Polks lose their composure. While my ears couldn’t handle that kind of volume for long, it sounded like the LSiM system could have taken the punishment all day long.

Earlier, I noted that I had received both the LSiM 703 bookshelf speakers and the 702F/X speakers to use as surround channels. I’ve found that I typically prefer direct radiating speakers for surround use and in the case of the 703s versus the 702F/Xs that held true once again. Although their frequency response is similar, the 703s were a richer sounding speaker, with more extended bass and to my ears a sweeter midrange and treble presentation. Their sound seemed to mate better with the 707 towers and 706c center channel which helped to create a more seamless surround field. This was particularly noticeable with surround music. I will admit that the 702F/Xs, with their slimmer wall mounted silhouette, could blend in better from an aesthetic perspective. However, make sure that you can place them in a position where the tweeters will be firing directly towards your listening position or you will suffer from increased treble roll off. I’d also like to point out that that the 703s are fantastic speakers in their own right. I spent some time using them in my 2-channel family room system and was thoroughly impressed. Everything I wrote about the 707 towers applies to the 703s, except for the deepest bass. While they are large for a bookshelf speaker, the 703s can play extremely loud and have enough bass to make a subwoofer optional. If you are looking for a high-end bookshelf in this price range, it would be a sin not to audition the 703s.


Conclusions about the Polk LSiM Home Theater Speaker System

I had the pleasure of reviewing Polk’s less expensive RTiA range a few years ago. While I was very impressed with those speakers, I was even more impressed with the LSiM line. For everything the RTiA speakers did well, the LSiMs did it better: deeper and more accurate bass, more extended and airy treble, a smoother yet more accurate midrange, better musicality and life, increased soundstage width and depth, and improved imaging. Overall build quality was also noticeably superior, as it should be given the price difference. However, the biggest difference between the two lines is that when listening to the LSiM system I felt like I was hearing a well-executed, no compromises, high-end design, not just a system that sounded amazing for its price point. This is the type of speaker system that will grow with you as the quality of your source components progresses. While I can’t say that this system is cheap, if you want a serious dosage of what high-end audio is all about Polk’s LSiM series could be just what the doctor ordered.