Polk Audio LSiM703 Bookshelf Speaker Review

Polk Audio LSIM703 Introduction

Polk Audio is one of the most well-known names in the entire audio marketplace. Throughout my years as a home theater installer I saw more people using their old Polk Audio speakers than any other brand, except maybe Klipsch. Over time, Polk has slowly shifted from a focus on two channel systems to a product offering with an emphasis on home theater and price points that appeal to the mainstream consumer. But they have not forgotten about the high-end crowd, even if the high-end crowd has started to dismiss them. When Polk first announced their revamped flagship LSiM lineup in 2011, Tom wrote up a preview article that ended with, “We can't wait to get our hands on a pair to try them out.” Well, the wait has been long, but we have finally had the opportunity to sit down with the Polk Audio LSiM703 and give them a full run through. And it was well worth the wait.

Overview & Build Quality

The new LSiM series is a refresh of Polk’s previous flagship line, the LSi series. When I say flagship, I’m not talking about products priced into the stratosphere. Polk has kept the prices very low in comparison to most other speaker manufacturers. The most expensive offering is the LSiM707, a large floorstanding speaker for $1999/ea. Although this line is considered “budget” for some, Polk managed to pack much more technology and quality engineering into these speakers than most of the competition typically does at the same price point.

For starters, the top of the cabinet is curved, and the sides taper off towards the back to create a wedge-shape. This helps reduce internal resonance and standing waves, but it also makes the speaker look cool and less "boxy". The enclosure itself is made of MDF with 1” baffles on the sides, ¾” on the back and bottom, and 1 a ¼” thick front baffle. Everything is then finished off with a hardwood veneer, available in such creative names as Mt. Vernon Cherry or Midnight Mahogany. I attempted to take the speaker apart to get a better look at internal bracing, but the only visible screws are on the binding posts…and it’s glued in place. So, no internal pictures for this review.

The 703 is a 3-way design with a 6 ½” mid-woofer, 3 ¼” midrange, and 1” ring radiator tweeter. The tweeter and midrange are part of what Polk calls its Dynamic Sonic Engine. Other than having a nifty sounding name, this means there is a single molded piece that holds both the midrange (in its own enclosure) and the tweeter (which also includes the baffle). The Dynamic Sonic Engine (read: tweeter and midrange) is inside an enclosure with 1 ¼” baffles, separating it from the 6.5” mid-woofer. Separating drivers within a cabinet is a great practice, and shows that Polk is serious about these speakers.

The mid-woofer and midrange cones are made of Polk’s new Super Cell APP. This is an improvement on their aerated polypropylene (APP) material and is supposed to be more ridged and lighter in weight. Both the mid-woofer and midrange drivers have cast aluminum baskets (another plus), while the mid-woofer has butyl rubber surrounds (and dual spiders) and the midrange has foam surrounds. The tweeter is a new ring radiator design that Polk developed for the LSiM lineup. They extended the frequency response up to 40kHz (only flat up to 20kHz), reshaped the phase plug, moved the tweeter out further on the baffle, and added a host of other changes you can read about here. I was particularly glad to hear about the redesign because I haven’t been a big fan of their previous ring radiator tweeters.

Polk Audio LSiM 703 PowerPort

On the rear of the speaker you will find Polk’s proprietary PowerPort technology. PowerPort is a cone that sits at the mouth of the port. Polk claims this reduces port chuffing and has the same effect on bass that a longer port tube would. While I would take that statement with a grain of salt, the bass from these speakers was powerful and clean. Below the PowerPort are two sets of high-quality binding posts that allow the speaker to be bi-amped or bi-wired. Unlike less expensive speakers, these binding posts just ooze quality, and easily held the heft of my giant Monster M2.2s speaker wire.

With three drivers in separate enclosures and a large rear-firing port, you might be wondering how large these speakers are. At nearly 17” high, 9” wide, 15” deep, and 30 pounds, these are some serious bookshelf speakers. I felt safe with them on my Sanus SF26 stands, but this is as large and heavy of a speaker as I would put on them.

The 703’s have a rated frequency response of 36Hz-40kHz, but that’s not the -3dB point. With a -3dB reference, the 703’s will play from 50Hz to 30kHz. This is deeper than most bookshelf speakers, but they are also larger than most speakers in this category. The entire LSiM lineup has a rated sensitivity of 88dB, which is a little low, but the Anthem M1 amps I used are rated at 1,000w 8ohms, so I had no issues driving the 703’s well past comfortable listening levels. Those who are trying to play them at extremely high levels in larger rooms might want to have some beefy amps.

LSiM703 First Impressions

When the UPS delivery truck pulled up to my home to drop off the LSiM703's, I quickly signed off for them and started the unboxing process. The first thing I noticed was a hole in the side of the box large enough for me to fit my entire hand in. So, what did I do? I stuck my hand inside the box to see what type of protection the speakers had from punctures to the box. I was able to reach in and grab the speaker without opposition. As I started to unbox the 703’s I noticed that there was only Styrofoam on the top and bottom, with no protection in the middle. The speaker sat loosely in the Styrofoam, and the Styrofoam sat loosely in the box, allowing for everything to jostle around a bit during delivery. The speaker itself is wrapped in a soft cloth and a plastic bag, to prevent damage from dust, dirt, or moisture. Fortunately, there wasn’t any damage to the speaker, but I would like to see a little more robust package design for such a nice speaker.

Polk Audio LSiM 703 Binding Posts

After I unpacked the LSiM703, I visibly inspected them and noticed some minor scuffs on the bottom and around the logo. I am not sure if these had been used previously (as is sometimes the case with review samples), but nobody looks at the bottom of the speaker anyway, and the mar on the logo scratched off easily when I rubbed it with my fingernail. The scuffs on the speaker might also be due to insufficient buffing at the factory. Either way, they were only noticeable under very close inspection and shouldn’t affect your purchase decision. Once I had them setup, I stepped back to take a look at the whole package, and they looked great! There’s no getting around it, they’re big, but the glossy front baffle and curved top make them look nice and big, not big and ugly.

 Listening Tests

Listening tests were performed in a nearfield formation, with the speakers approximately 6’ apart and the listening position 7’ away. I ran analog cables out of my Oppo BDP-93 directly into a pair of Anthem M1 Monoblock amplifiers and connected the speakers using Monster M series M2.2s speaker cables. This setup made for a very clean signal path, short cable runs, and very low noise floor.

Johnny Cash – American VI: Ain’t No Grave

I absolutely LOVE this album. Not only does it remind me of days long past sitting with my father and playing a game of cribbage with smoke slowly rolling off his pipe and a fiery Cash singing in the background; it shows the progression of a music legend. The American collection shows an aged man. The songs wrestle with getting past vanity, seeking peace, moving past pain, and coming to terms with the inevitability of death. Track 1, “Ain’t No Grave” is a simple sound, much like the rest of the CD. Johnny Cash’s voice floated in the middle of the soundstage, with a few guitars plucking notes and a kick drum in the background. There’s also a repeating sound of a chain dropping to the floor. Through the 703’s the chain sounded strong and heavy. In comparison, through my MartinLogan LX16’s, the chain had no heft (ie. lots of treble, lack of midrange). Track 2, “Redemption Day”, starts with twin guitars, one out of the right speaker and the other out of the left. All of sudden Cash’s voice came out of the middle of the soundstage, with miles of dead space in between the three instruments (yes, the voice is an instrument!). My favorite song on the entire CD is “Satisfied Mind”, and the LSiM did it more than justice. It felt like Johnny Cash was sitting right in front of me, providing a sense of realism every speaker strives for. The LSiM sucked out every drop of detail in this song, so much so that I could clearly hear every time his lips came together and the saliva split apart when he opened his mouth again.

Ray Charles – Genius Loves Company

This entire CD normally has a very subdued feeling, but the LSiM’s made it more of an in-your-face experience, which I actually appreciated. I always thought this album was missing just a little something on the top end, but the 703’s added it back in. The cymbals in “Sweet Potato Pie” seemed to decay for an eternity, and James Taylor’s voice felt rich and powerful. Track 4, “Sorry Seems to Be the Hardest Word” is my favorite song on the entire album, mostly because it’s a duet between Ray Charles and the legendary Elton John. Elton John’s voice comes in at about 40 seconds into the song and sits just to the left of Ray Charles. This was probably the best I have ever heard this track reproduced. The drums were tight, the voices were lifelike, and the bass was authoritative. The opening of track 5, “Fever”, has a simple bass rift that smaller bookshelf speakers balk at, but the 703’s stood up and handled it with ease. So, I pushed them a little farther, and a little farther, but they never lost composure. At this point I was pretty impressed.

Santana – Supernatural

I’ve never been a big Santana fan, but I picked up Supernatural a while back after seeing that Gene had used it for listening tests, plus, it was only $.99 at a local used record shop. I have been pleasantly surprised with the quality of the recording, immense musical talent, and variety among the tracks. One of Santana’s most popular songs, “Smooth”, is a track rich with a plethora of musical instruments layered one on top of the other. The 703’s pulled out every bit of detail, with a slight bit of brightness on some of the artificially distorted vocals. “Do You Like the Way” has a rapid, yet delicate interplay between Lauryn Hill & Cee-Lo. Both voices sounded natural, separate and clearly delineated in the mix, in their own space. They didn’t end up muddled together or intelligible, as can happen with other speakers. “El Farol” starts out with an interlude of drum, bass guitar and bongo. Each instrument sat perfectly in its own space, something I kept coming back to with this setup. The low noise floor of the equipment, power of the M1 amps, and abilities of the LSiM703s came together to create a deep, wide soundstage. All I could hear were the instruments, not a hint of distortion or noise. It’s like each musician was standing in a black hole, with an infinite amount of space around them. I think it’s safe to say that I will be adding Santana to my list of commonly used test discs.

Polk Audio LSiM703 Measurements & Conclusion

I was pretty limited in my allotted time to take measurements of the 703’s, and only noticed afterwards that I needed to retake the ground plane measurements because of an incorrect setting in the OmniMic Software. Such is life. Still, I managed to take good on and off axis measurements—they just don’t tell you much about bass response because of room interaction. All measurements were taken indoors at 2m to allow the sound from the drivers to properly combine.

Polk Audio LSiM703  In-room 2 meter SPL vs Frequency Response

This is a single on-axis measurement, not a listening area average. The response below 300Hz is rather sloppy, but that is largely related to room interaction. The characteristic that’s most important here is the very flat response up to about 6kHz, where the treble starts to climb. This rise explains why in some tracks the speaker was too bright, but because the rise isn’t significant till about 6kHz (most of what you listen to is below this), most tracks were pleasant to listen to. Still, I would have liked Polk to pull back the tweeter because the boost in treble made me turn down the speakers on some tracks, when I could have gone louder with more laid back treble.

            Polk Audio LSiM703  In-room 2 meter SPL vs Frequency Response

black trace: on axis; red trace: -15 degrees horizontal; blue trace: -30 degrees horizontal 

As you can see from the above graph, the off-axis response is quite uniform. Within 15 degrees there is only a slight drop above 9kHz, but at 30 degrees off-axis the roll off is much more dramatic. Once you are off axis by 30 degrees or more the sound changes dramatically (for the worse), something I noticed when sitting off to the side while giving demos to friends. Although this graph only shows horizontal off-axis measurements, I did take measurements +/-15 degrees vertically, which were nearly identical to on-axis measurements.

Conclusion

I hate reviewing products like the LSiM 703s for two reasons. First, they make me look bad. A reviewer is supposed to be critical about a product, but what am I supposed to do when there’s little that’s bad to talk about? Writing only positive reviews could ruin my reputation. Second, I don’t want to send back good products. I would be happy with the company making a clerical error and somehow leaving the product here for an extended period of time (are you listening Polk??). So, not only do I look uncritical by writing up a great review, I am also left empty handed when I send the speakers back to the manufacturer. What can I say? The LSiM 703 speakers look great, sound great, and are reasonably priced. I think they are an excellent bookshelf speaker and would gladly recommend them. I hope you’re happy Polk, you’ve ruined my day.

The Score Card

The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:

Performance × Price Factor/Value = Rating

Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.

Audioholics Rating Scale

• — Excellent
• — Very Good
• — Good
• — Fair
• — Poor

Metric	Rating
Build Quality
Appearance
Treble Extension
Treble Smoothness
Midrange Accuracy
Bass Extension
Bass Accuracy
Imaging
Soundstage
Dynamic Range
Fit and Finish
Performance
Value