Polk Audio LSi Series Speaker System 
Home Theater Loudspeakers Speaker Systems
Written by Matthew Evert   
Thursday, 01 April 2004

Polk Audio is a trusted name in home and car loudspeakers, offering high quality transducers at very fair prices for decades. Founded in 1972 by two audiophiles, Matthew Polk and George Klopfer, Polk Audio has grown to become one of the world’s most successful brands of high-quality home loudspeakers. Polk Audio prides itself in having employees that truly love music and care about good sound rather than people that just “sell boxes.” The LSi Series loudspeakers are Polk’s most recommended line of speakers for “serious listeners.” The LSi home theater speaker system evaluated here includes the LSi15s at $1,740 per pair, used as the main loudspeakers, a LSiC center channel speaker at $580, and a pair of LSiFX surround speakers costing $1,060 per pair.

The LSi15s are tall and sleek works of art. They stand eight-and-five-eighths inches wide by 45.5 inches high by 13 inches deep. Tipping the scales at 66 pounds each, these are not lightweight speakers by any means. The cabinet consists of a high gloss black laminated main cabinet made of three-quarter-inch medium density fiberboard (MDF) with double thickness side panels covering the bottom two thirds of the main cabinet. The side panels, available in cherry or ebony, serve as extra dampening to further deaden the cabinet. Careful thought was put into the design of the cabinet to isolate the mid/high-frequency drivers from the eight-inch side-firing woofer in the lower half of the cabinet. The LSi15 is mounted on its own stand to make room for a uniquely designed floor port for the woofer. This port features a cone, as Polk’s marketing team explains, that promotes an orderly flow of air exiting from the enclosure without creating any additional noise due to turbulence and increasing speaker efficiency.

The LSi15s sport a one-inch Ring Radiator tweeter, two five-and-a quarter-inch aerated Polypropylene drivers and an eight-inch woofer. Polk calls this a “3.5-way” design speaker that includes an unpowered woofer. All five speakers feature the same aforementioned tweeter and drivers. The tweeter is quite an impressive component, with the same technology used in Krell’s $35,000 Revolution speakers. The low-mass woven diaphragm is supported at two pivot points with the voice coil located in the middle of the points. This allows for less unsupported regions of the diaphragm and thus less audible resonance from the tweeter. The drivers are made of air “foamed” polypropylene that yields a cone that is 15-20 percent lighter than traditional polypropylene cones. These lighter cones result in less driver resonance. Each speaker also features dual gold-plated five-way binding post inputs for robust wiring configurations. These posts allow each speaker to be bi-wired or bi-amped.

Polk speakers were designed to last. Each speaker is subject to rigorous environmental testing to make sure that ultraviolet (UV) light does not degrade the speakers’ rubber and plastic parts for well over 20 years. Heat and humidity tests are also done to make sure these speakers hold together for a lifetime.

For movie dialogue reproduction, one needs a good center channel. Polk delivers with the LSiC. This matching black high-gloss cabinet features a ring radiator tweeter and two five-and-quarter-inch midrange drivers. This rectangular cabinet stands seven-inches tall, 21.75 inches wide, nine inches deep and fit nicely on top of my 32-inch Toshiba CRT.

The LSiFX surround speakers are the perfect match to the LSiC and LSi15 speakers, with a matching black gloss finish and black grille. The set of all five speakers shine like Darth Vader’s polished helmet and wield the Force, as does Mr. Vader. By the Force, I mean plenty of musical power and detail, not supernatural powers. That said, at 24 pounds each, they could be a little heavy for one person to mount on a wall, so I suggest you take your time in setting them up and recruit a friend if possible (ideally Yoda, if he is available). The FXs are much larger than my old Energy Take 2 speakers at 15 inches tall, 13.75 inches wide, and 10 inches deep. The FXs are more versatile, featuring a switch to adjust from dipole to bipole mode and having the bi-ampable binding posts. The bipole/dipole switch is located under the right grille on each speaker and is handy if you are limited in where you can mount the speakers. I have a window towards the middle back of my listening room, so I opted to use the bipole mode and mount the speakers slightly behind my couch. If you prefer to mount the speakers directly next to the listening position, it is recommended to use the dipole mode instead. I found this to be a very nice feature. Again, the FXs used the same mounts for the wall. Although awkward to hang on the wall, the mounts also are functional in that they feature the “nipples” on the power ports for reduction of noise stemming from high velocity air exiting the speaker. As with the LSi15s, the power ports route bass energy directly to the wall mounts and thus generate some needed thump towards the back of the room.

The LSi Series speakers are well-constructed and are well matched with each other. The LSi15s were placed about seven feet apart and about 32 inches from the front wall. I also tried to pull them away from the sidewalls by about 22 inches to let them breathe and improve imaging. The floor-mounting stand for the LSi15s make a good lift point for moving the speakers around. Just be sure to lift them from the back of the speaker, since the front grille is fragile and spans the entire length of the speaker. After targeting the LSi15s’ drivers at a point about a foot behind my head in my listening position, I was quickly up and running with richly detailed stereo sound. The speakers were broken in for me by Polk, yet I ran music through them for an additional 50 hours prior to evaluation to be sure they were ready to go. I listened to the LSi15s for a while with my Parasound preamp and amplifier and later through the Harmon Kardon AVR630, a receiver that I’m reviewing in an upcoming issue.

After the mains were set up and dialed in, I quickly got the center mounted on top of my TV and bi-wired into my receiver. When using a receiver, be sure to select the “large” setting for the front LSi15 speakers. I made this mistake once and the woofers had no “woof” to them. You can use the “small” setting for the LSiFXs and the LSiC. I tried listening to some movies with and without my Energy ES10 subwoofer, and preferred the bass reproduction of the ES10 to the woofers built into the LSi15s. I found the system sounded best with the ES10 turned on and the receiver passing everything below 80Hz to it. If you do not have a subwoofer, then obviously you will be pleased to have the LSi-15s’ woofer there to help out in the bass department. The LSiFX speakers are versatile and once I figured out where the only feasible place was to mount them (I have windows and doors that tend to complicate my room set-up), they were very flexible with the dipole/bipole switch. Polk provided some handy mounting templates so that you can get the correct distance between the two mount screws marked on your wall. Mounting them was a bear, but with the help of a friend, they mounted up after some tweaking of the mounting screws and locating some material to place under the mounts to take care of annoying rattle when played at volume.

With the Parasound preamp and amplifier, I ran one of my favorite recordings through the LSi15s, the Song Review album from Stevie Wonder (Motown Record Company). Wonder signed with Motown Records at the age of 11 and had his first hit in 1963. He has revolutionized modern pop and R&B music with his innovative use of high hats and percussion to complement his unmatched talent as a singer/songwriter and a keyboardist. “Sir Duke” is a prodigal example of his use of keyboard bass and prominent tapping of high hats to complement a big band of trumpets and horns. The LSi15s sang to me and brought out the high frequencies of the high hats with rich detail. The mids to upper mids of the trumpets were sweet and a little forward in their presentation. Light sounds such as the cowbells and the banjo-like picking of the electric guitar could easily be heard amongst the myriad of other sounds simultaneously tickling my ears. “Part-Time Lover” is a great example of Wonder’s vocal range and the LSi15s provided a sweet, detailed and energetic reproduction that showcased his talents. The chorus of the backup singers was not drowned out and somewhat congested as with my Energy C-6s. The LSis simply had more detail.

Switching to the Harmon Kardon receiver for multi-channel music and the movies, I noticed the limitations of the speakers with a lesser amplifier (in terms of power and clarity of amplification). The 16-bit stereo CD of Sting’s Brand New Day (A&M Records) was a noticeably more powerful performance than the DTS version that I demoed with the receiver. Still, I was impressed by this 5.1 recording and enjoyed my listening sessions on the lesser-powered receiver. The DTS version of “Big Lie Small World” was tantalizing, with its silky violins swaying and the lush sound of the muted trumpets in the background. Sting gives a jazzy-lounge singing performance to set the mood and relax the fortunate listener. “After the Rain Has Fallen” is more of an upbeat song that uses various percussions to complement the pop-like singing of Mr. Sumner. The tambourines rattling and sounds of hands clapping were pleasant to the ears and solidified the beat in my toes. The LSi15s really can reproduce the full spectrum of the audible range with solid detail. At times I felt the Energys were more musical, but the detail was clearly better with the LSi15s. At higher volumes, the LSi15s caused my ears some fatigue with some of the high-frequency elements on this album, but only after extended periods of listening.

“2 Fast 2 Furious” (Universal) is an excellent choice for anyone wanting to test the bass reproduction of a speaker system. It provides a lot of explosions and rap music to test the dynamics of your system, and lots of bad acting to test your patience. The initial race when Paul Walker gets busted by the cops is unquestionably intense. Paul takes on three other street racers, each with their own tricked-out rice rocket, customized to their personalities. The spooling up of the turbos whistles cleanly through the tweeters of the LSi15s. The screeching of the tires and howling of the engines had me at the edge of my seat, until the final jump when Paul leapfrogs the leader and rakes in the cash. The rap music is so strong in bass that I had to almost turn off my subwoofer. The LSi15s had plenty of bass, but it was not overly boomy. The bass was quite tight and agile. It was easy to distinguish between the bass of the engines revving and the bass of the music. The Energy C-6s sometimes would bleed the bass sounds of similar frequencies together, making it harder for your ears to separate them as distinct sounds.

Without a doubt, one of the most influential pioneers of hard rock is AC/DC. No kid can graduate seventh grade without listening through the Back in Black album at least once. The DVD “Stiff Upper Lip Live” (Elektra) is a collection of 21 classics performed in a huge soccer stadium in Germany. “Rock and Roll Ain’t Noise Pollution” is a song from the Black in Black album, featuring Angus Young on his famous Gibson SG guitar. Young does his little guitar riffs while running up and down the stage extension to warm up the crowd of over 80,000 rock-hungry Germans. The raspy voice of Brian Johnson is clear, as there is no sign of grain or harshness from the LSi15s and the LSiC. The expressionless Phil Rudd is all business in the drum section and the snap of his snare drum pounded in my chest. “Bad Boy Boogie” is a track from the old Bon Scott days of AC/DC. This excerpt boasts all the talents and antics of Young onstage. He does his trademark duck walk across the stage and then a little striptease for the audience. A fast-pace beat and extended rhythm guitar melody by his brother, Malcolm Young, eventually leads to the disrobing of the petite Angus. Then the massive guitar solos erupt onstage. The viewer better hold on to something nailed down, ‘cause the head-banging is about to commence.

The hilarious film “Jay and Silent Bob Strike Back” is the fourth installment of the Kevin Smith movie series. Smith is modern America’s version of Monty Python-style humor that has entertained millions for years. “Clerks” introduced the characters Jay and Silent Bob to the world. Now, the crass and moronic duo get their own movie. Previous stars of Smith’s movies, such as Jason Lee and Ben Affleck, return for this one, and so does the comedy. The scene at the Mooby Burger restaurant has got to be my favorite, with the pair writing obscene emails and shouting about it while young kids look on. Then the sultry Shannon Elizabeth struts in and Jay daydreams about making out with her. Naturally Bon Jovi’s “Bad Medicine” cranks in the background and the audience is pulled into Jay’s elaborate fantasy. The frequent rock interludes on the soundtrack are handled gracefully by the LSi Series combination and complete the movie viewing experience.

The Downside
The LSi15s speaker grilles are unecessarily long and cumbersome. They seem a little flimsy and cheap compared to the rest of the speakers’ beefy contruction. However, according to Polk, the open edge design of the grille is intended to reduce diffraction for better imaging with the grilles on and a more robust grille would sound worse. It's a trade off. The speakers come only in high-gloss black (except the LSi15, which can also be purchased in cherry). This very limited selection of colors could be a turnoff for some when trying to blend these large speakers into modernly decorated homes.

The surround speakers have subpar mounts on them. The lack of rubber parts on the mounting surface cause the speakers to rattle at certain frequencies, which is especially obvious when the surrounds are played at volume. I solved this by cutting up an old mouse pad to place between the mounts and the wall. The mounts on the LSiFXs are made of plastic that scratches easily and are difficult to install (trying to have one person eyeball the mounting slots and the other lift the heavy speakers was tricky). The difficult time with getting the screws the right depth and the slots on the mounts lined up made it nearly impossible to hit the target on less than two or three tries. The result of these failed attempts was a scratching of the mounts against the mounting screws with every try. Lastly, I recommend that you have a properly matched amplifier to these speakers. You don’t need a 300-watt Mark Levinson amp, but an under-powered receiver will simply not provide the power necessary to make these speakers sing. The LSi-15s were far from the hardest load my amplifier has seen, yet they’re far from the easiest.

Other speakers with prices similar to the LSi series are the Defintive Technologies BP2004TL at $1,600 a pair and the Energy C-9 at $1,500 a pair. The BP2004TL boasts a better response range (18 Hz-30 kHz) and a better efficiency (92 dB versus 88 dB for the LSi15). The improved efficiency may be important to consider if you have a weaker amplifier or receiver and are not able to drive the LSi15s. The BP2004TL also sports a powered 10-inch woofer.

The Polk Audio LSi Series Speakers make an excellent addition to any modern day home theater system.

Many of my friends came over to my place during the months I has my Polk set. They consistently commented on how they were surprised by details of sound that they’d been missing out on with their existing speakers. At $3,400 for the set of all five speakers, the Polk LSi Series speakers are not cheap, yet they are what I consider to be an excellent high-end audio value. Sure, speakers get better, but you start to embark upon the point of diminishing returns where the product get exponentially higher-priced as the performance makes smaller steps. The superiority of this Polk system vs. other more mass-market speakers that you might find pre-installed in your car or as part of your clock radio is a no-brainer. The Polks rock. You have many choices in the $3,500 price range for 5.1 speakers, but few of them will have nearly the detail and versatility that the Polks do. With a five-year warranty and a 30-year track record of producing quality speakers, Polk Audio is always a good bet.
Manufacturer Polk Audio
Model LSi Series Speaker System
Reviewer Matthew Evert

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