This product is a vintage Polk model and is not available for sale, but it may still be available in some stores as a closeout or used product. The following text is taken from the original sales brochure for this product and does not reflect current availability. If you happen to have any question or concerns about this product, or any other Polk Audio product, feel free to contact our Customer Service Department at 1-800-377-7655 Monday - Friday, 9am - 5:30pm EST


Floorstanding Loudspeaker, 10'' Powered Subwoofer

Available Finishes:

The Flagship Floorstanding Polk Audio Loudspeaker

"The LSi is for the serious listener; the person who really enjoys music, who sits down and intently listens to his stereo system. This person could be a serious home theater enthusiast, too. They want to hear every detail a movie soundtrack has to offer. There's no question these speakers play loud, but the LSi Series is for the listener who is more interested in quality over quantity."
- Matt Polk, Founder, Polk Audio

Here is superior musical accuracy and serious theatrical impact in one beautiful, high tech loudspeaker. Here is the sound of life, live on stage, realistically imaged and projected with no coloration. Here is wide, deep, whispers and explosions, with all the bells and whistles. Here is clarity, with low resonance and no distortion. Here is high definition audio. Here is the heart & soul of the Polk Audio sound in a commanding floorstanding performance.

Built-in Powered Subwoofer

Low level line (filtered) and LFE (unfiltered) subwoofer inputs access the 10" built-in powered subwoofer, powered by a clean-running 150 Watt internal amplifier, which allows the LSi25 to deliver truly astounding, ultra-dynamic full-range performance.

Ring Radiator Tweeters

The ultra-high performance Ring Radiator Tweeter is found on ultra-high end, luxury-priced speakers. We've brought the Ring Radiator down to earth for your enjoyment. In the LSi Series, you will experience its precise accuracy, meticulous detail and extended, low distortion frequency response at a fraction of the price.

Dynamic Balance Aerated Polypropylene Drivers

Why does the LSi Series sound so warm and natural? It's what they're made of that matters. Aerated Polypropylene is stiff on the outside, for excellent transient response, but "light & chewy" on the inside, providing light mass with importrant damping qualities. Using our patented, laser-based Dynamic Balance process, we've eliminated areas of resonance on the cone in the planning stages, so bad sounds never make it to the final product. As a result, the LSi Series sounds like a Polk Audio loudspeaker should: realistic, transparent, wide and embracing, with no distortion even at lifelike volume levels.

Cascade Tapered Array

This advanced crossover configuration works with the multi-driver array to deliver wider dispersion and greater midrange accuracy. The LSi Series reveals realistic sound, even in off-axis listening positions, and improved image focus and detail.

Mirror-Imaged Pairs

The LSi Series is not just single-design speakers tossed together in pairs. We've engineered them to be mirror-imaged pairs, with specific Left and Right designations. Mirror-imaging the pairs produces astonishingly tight focus and truly arresting three-dimensional imaging with minimized room reflections. Your audio opens up, naturally.

Cast Aluminum Driver Baskets

Rigid Cast Aluminum Driver Baskets resist flexing and "ringing" for ultra-tight bass and coloration-free midrange.

Non-Resonant Braced Piano Gloss Enclosure

Superior workmanship is plainly evident in the furniture-grade piano finish of each LSi Series speaker. It's a loudspeaker that lives up to its reputation for classy presentation, and blends well with traditional or modern decor. Inside, the enlosure is extensively braced with heavy duty MDF and damped with professional damping material. No energy is lost in unwanted cabinet resonances, for smooth, untarnished reproduction of even the most extreme audio. Next time you meet them, give them The Knuckle Test (knock, knock!) and feel the solid, non-resonant build quality.

Real Wood Veneer Panels

They look great, and serve a purpose, too. These solid, non-resonant, 1.5"-thick heavy duty panels reinforce the enclosure's solid quality, helping it remain totally and more efficiently acoustically inert. Choose beautiful natural Cherry Wood or Ebony Wood finishes to complement your home. (LSiC & LSiF/X models available in Black Gloss only.)

PowerPort Bass Venting

Floor-coupled on Floorstanding models, traditional rear-firing on other models, the patented PowerPort Bass Venting System smooths the big moving air turbulence at the mouth of the speaker's bass port, effectively enhancing deep, musical bass response and aiding over-all full-range blending between frequencies. Bass response in the LSi Series is efficient, precise, natural, unimpeded by distortion. This is lifelike bass you can feel all over.?

ARC Port

LSi Series speakers overcome the midbass "boominess" that can make vocals sound unnaturally "chesty" with another patented technology: Acoustic Resonance Control. The ARC Port is a separate port coupled to the bass port and tuned to supress the internal cabinet resonances that can interfere with high performance audio reproduction. You will hear clear, resonance-free midrange and more accurate vocal reproduction in the LSi Series. (Available on all LSi Series models except LSiF/X, where there's less call for accurate vocal reproduction.)

Magnetically Shielded

All models of the LSi Series are engineered to be safe when placed near sensitive AV equipment like monitors or TVs. (Available on all LSi Series models except LSiF/X, which never goes near your TV anyway.)

Premium Crossovers

High performance materials minimize the need for electronic manipulation of audio reproduction (that is, the LSi Series sounds great from the start), but we've designed a high performance crossover system to boost performance just that much more. Premium components, like Mylar Bypass Capacitors, extend and flatten responses, especially in the higher, detail-oriented frequencies. You will discover musical details you've never heard before, even in your favorite high performance digital audio.

Low Diffraction Grille Design

The unique open architecture design of the acoustically inert LSi Series speaker grille never gets in the way of the sound.

Gold-Plated 5-Way Binding Post Connectors

Dual (bi-ampable) gold-plated 5-way professional binding post connectors give you maximum signal transfer and the most secure professional connections.

Adjustable Footing

Floorstanding LSi Series models feature precisely engineered footing options, interchangable Non-Skid Leveling Feet or Carpet Spikes, for the ultimate stability on any type of floor. More stability equals more efficiency, less energy wasted, and more pronounced performance.

Perfectly Matched to LCi In-Wall/In-Ceiling Speakers

Designed with the same high performance components, including the Ring Radiator Tweeter and? Aerated Polypropylene Drivers, the LCi Series of built-in loudspeakers can be used to complete or extend a traditional system of LSi Series loudspeakers. Add built-in surrounds to a home theater system, or add second-zone speakers to a music system. LCi Series built-in loudspeakers deliver the same incredibly warm and natural LSi sound in a speaker series that can virtually disappear into your decor.

Famous Polk Dependability & Durability

Like all of our products, the LSi Series uses only the best materials coupled with the most advanced manufacturing techniques on the planet. All Polk products must pass a battery of the most physically strenuous and exhaustive performance tests in the industry, including drop testing and extreme signal response testing. Polk Audio loudspeakers are proudly built to perform for a lifetime.

Polk Audio Customer Service: The Gold Standard

Call or email us and you'll be connected to real live human who knows just about everything there is to know about audio and performance electronics. From "how do I get started?" and "what should I buy?" to "how do I stop that hiss?" and "which tube needs replacing?" and everything in between, we know the answers you need to get back to enjoying your audio entertainment pronto. Just ask.

Driver Complement

Diameter1" (2.54cm) 
TypeDynamic Balance Ring Radiator (shielded) 
Mid / Woofer
Diameter5 1/4" (13.34cm) 
TypeDynamic Balance with aerated polypropylene cone, cast basket and rubber surround (shielded) 
Diameter10" (25.40cm) 
TypePolymer composite cone with rubber surround (shielded) 


Total Frequency Response20Hz - 27kHz 
Upper -3dB Limit26 kHz
Lower -3dB Limit30 Hz
Nominal Impedance4 ohms
Efficiency88 dB
Mid-High Array CrossoverDriver 1: HPF at 80Hz 12dB/oct, LPF at 800Hz 12dB/oct.
Driver 2: HPF at 80Hz 12dB/oct, LPF at 2.4kHz 12dB/oct.
Tweeter: HPF at 2.4kHz 18dB/oct. 
Subwoofer CrossoverLPF variable 60Hz - 180Hz 12dB/oct. 
Recommended Amplifier Power20 - 300 watts per channel
InputsDual gold plated 5-way binding posts. Line level subwoofer input (filtered) and LFE subwoofer input (unfiltered) 
OutputsLine level passthrough 

Amplifier Specs

Bandwidth20Hz - 200Hz 
220V AvailabilityNo 
Continuous Average Output
Amplifier TypeSubwoofer 
Dynamic Power300 watts


Cabinet Dimensions
Height49 3/4" (126.36cm) 
Width8 5/8" (21.91cm) 
Depth17" (43.18cm) 
Enclosure Type
Mid-High Array Enclosure TypeVented via dual ARC ports 
Subwoofer Enclosure TypeVented via floor-coupled PowerPort 
Width9 5/8" (24.45cm) 
Depth16 3/8" (41.59cm) 
Product Weight (each)91.00 pounds


Unit of Measureeach 
Total Shipping Weight100.00 pounds
Included AccessoriesCarpet spikes and rubber feet 


Speaker Warranty5 years parts and labor (original purchaser) 
Subwoofer Amplifier Warranty3 Years parts and labor 

Specifications, dimensions and features subject to change without notice. For more information call us at 1-800-377-7655 (USA and Canada). Outside of North America call +1 (410) 358-3600.

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