Floorstanding

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

SDA 2A

Classic Polk Full Range Loudspeakers

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The Genius of Matthew Polk: SDA True Stereo

This 3rd Generation of SDA Loudspeakers incorporate many of the advances in SDA technology pioneered in the Signature Edition SRS and SRS2, including a full complement Sub-Bass Drive, Time Compensated Phase Coherent Driver Alignment and Bandwidth-optimized Dimensional Signal technology.

What Makes a Legend Most: The Paradigm Shift of SDA Technology

You're familiar with "stereo," the basic two-channel left-and-right channel separation of audio information. What you probably don't know is that reproducing "stereo" from a pair of loudspeakers is less accurate than it seems. In fact, it can be downright inaccurate. This is the problem that Matthew Polk and the engineers at Polk Audio set out to remedy in the mid-80s, just as the audio industry was transitioning from "boutique" brands, popular with a handful of hobbyists, to more mainstream popularity. It was a time of great innovation, and Polk Audio, already an established innovator, was on the forefront.

The problem with "stereo" was that it didn't really work. You sat in front of a pair of speakers, and your left ear heard stuff and your right ear heard stuff, and both ears heard information from both channels, left-and-right; each ear hearing information from both channels. It's called "interaural crosstalk." Interaural crosstalk occurs when left-channel (left speaker) information is heard by the right ear, and right-channel (right speaker) information is heard by the left ear. You can't avoid it, that's just the nature of sound. But it results in a completely unrealistic and inaccurate reproduction of sound, reducing the soundstage to a narrow "sweet spot," with muddy "stereo separation," and unrealistic "imaging."

To more accurately reproduce sound as it was originally created live, with lifelike imaging and separation, Matthew Polk realized the vital importance of maintaining the integrity of the channel separation. To do it, he had to defeat interaural crosstalk. So Polk Audio engineers designed a complex passive-circuitry crossover network for a new set of multi-driver loudspeakers. It would use patented algorithms and innovative sound-phasing to effortlessly cancel interaural crosstalk between the stereo pair. They called it Stereo Dimensional Array Technology, and it produced "True Stereo," a completely new kind of sound, where the left channel information is delivered to your left ear, while the right channel information is delivered to your right ear, and never the twain shall meet. Each ear hears what it is meant to hear, with full stereo separation, as if the performance you are listening to is live.

SDA Technology changed the sound of home audio loudspeakers. It delivered a dramatic, dynamic, broad, accurate, lifelike soundstage with pinpoint imaging and realistic reproduction. And Polk Audio's flagship SRS Series loudspeakers were built to deliver it at the most extreme, lifelike volume levels. Home audio would never be the same.

Today's Polk Audio Benefits from Yesterday's Innovations

That was then, this is now. We've never stopped innovating. The changing nature of entertainment media (vinyl to CD to digital download) demands changes in reproduction technology. So we've miniaturized, digitized, redesigned, reformulated and re-engineered many of our original, patented groundbreaking technologies to better serve your entertainment needs and desires today. Many of our loudspeaker models still use variations on the original SDA Technology, along with other classic patented audio innovations like Dynamic Balance material tuning and innovative driver array designs, so you can still experience the classic warm, realistic, lifelike Polk Audio sound. Hear the difference a history of audio innovation makes. You'll understand why we're still "The Speaker Specialists."

SDA-2A

3rd Generation SDA Series, circa 1986-1987
Features the SL2000 Tweeter

"Spectacular! The result is always better than what can be achieved by conventional speakers." - Stereo Review Magazine

"Astounding! We have yet to hear any stereo program that doesn't benefit." - High Fidelity Magazine

"Superb! SDA has the ability to make your favorite speakers sound second rate!" -- Stereo Review Magazine

"Among the crop of new and innovative speaker systems [at CES], probably the most impressive was the Polk SDA SRS, which shook the walls of the Americana Congress Hotel." - Stereo Review Magazine

"Literally, a new dimension in sound." - Stereo Review Magazine

"They truly represent a breakthrough." - Rolling Stone Magazine

"Breathtaking... a new world of hi-fi listening." - Stereo Buyer's Guide

"True Stereo" with SDA Technology

One of the original breakthrought technologies patented by Polk Audio, SDA Technology allows a pair of loudspeakers to deliver an overwhelmingly wide, realistic soundstage with no interaural crosstalk, revealing the full impact of true stereo separation with pinpoint imaging accuracy. You will find this incredible, paradigm-changing technology in today's Polk Audio products, too.

Line Source Array Technology

The Line Source Array minimizes the damaging effects of unwanted sound reflections by controlling the vertical dispersion midrange frequencies. It's an exclusive Polk Audio engineering design, and eliminates blurred imaging and tonal coloration caused by floor and ceiling reflections of these important midrange frequencies. Line Source Array Technology "opens" the soundstage, reduces the effects of undesired room interactions, and achieves a more realistically-placed audio image, with a wider range of optimum listening positions in any room.

Progressive Point Source Technology

As performance frequencies increase during sound reproduction, the SRS Tweeter array actually adjusts its radiation area, becoming an ideal point source at the very highest of frequencies, eliminating high frequency interactions and reflections between the multiple drivers. Progressive Point Source Technology maintains a Constant Vertical Directivity of the mid and high frequencies, which prevents undesirable "beaming," and delivers astonishingly realistic "you are there" imaging.

Internally Braced Enclosures

The enclosure is an integral part of the design of the SRS Speaker Series. At a time when speakers were becoming more and more popular, many companies opted for the economy of cheap, flimsy materials. Polk Audio knew that the build-quality of the enclosure is just as important to the sound quality of the speaker as the material used to construct the driver cones. SRS Series speakers were constructed of heavy-duty MDF, and internally braced for additional stability and efficiency even at lifelike volume levels. Check the specs: these speakers weighed as much as a 6-year-old child. Reinforced baffles and a unique Low Diffraction Grille design virtually eliminated performance-robbing resonances, for less coloration, more efficient operation, and the most realistic sound reproduction possible. Today, Polk Audio loudspeakers continue this tradition of heavy-duty enclosure construction, producing the same excellent and efficient sound.

Dynamic Balance Material Design Technology

Dynamic Balance is Polk Audio's patented micro-analysis of a speaker's entire electro-acoustic and mechanical system. It was developed to help us select better materials and more efficient geometry when building the SRS Series to meet our extraordinary performance standards. Dynamic Balance analysis allowed us to pinpoint and eliminate performance-robbing resonances right on the actual driver material, long before they might become a part of the finished product. We were able to tune out offending sounds before you hear them! The performance of the Trilaminate Polymer driver material used in the SRS Series far outstripped the more traditional vacuum-formed plastic cones of the time. Using the Dynamic Balance process, the Trilaminate Polymer material was tuned to produce flat, uncolored frequency response. This true transparency revealed a wider dynamic range, with sharper details, and no hint of strain. Every driver and tweeter Polk Audio designs and manufactures today is tuned with the exclusive Dynamic Balance process.

Trilaminate Polymer Mid-Bass Drivers

For the kind of realism and deep bass response that you can actually feel, each SRS model features an array of Polk's exclusive Trilaminate Polymer Midbass Drivers. Designed and engineered in a proprietary process using three complementary materials, SRS Drivers deliver performance far beyond the reaches of conventional speaker drivers. The first laminate material was chosen for its structural strength combined with its light weight. The second laminate is extremely stiff with an unusually high speed of sonic wave transmission. The third laminate boasts a uniquely effective damping property that removes sonic coloration. Combined, these materials contribute to a driver that's light and fast, with low distortion and superior transient response and detail, even at truly astounding volume levels. Supported by a rigid motor structure, with high temperature aluminum voice coils to assure reliability even with extended playing at maximum output, and durable Butyl Rubber Surrounds allowing for more accurate cone movement, many of these drivers have survived since the SRS Series was first introduced and still play perfectly. This kind of material perfection can be found in every current Polk Audio model as well.

Critically Tuned Planar Bass Radiators

The SRS Series Mid-Bass Drivers are acoustically coupled to the speaker's Critically Tuned Planar Bass Radiator. A pair of SRS speakers with 15" Bass Radiators has a low frequency driver system of over 178 square inches. This is deep bass that is both emotional and physical, and has been described as thunderous. And yet this is a system designed from the start to be clean and tight, with virtually no distortion. The SRS Series has been found to yield less distortion at 25Hz than many audiophile quality tube amplifiers. SRS Series speakers included "Bass Brace" hardware to anchor your speakers to your floor, for the ultimate in efficient, exhilarating deep bass reproduction. We have gone on to use this extraordinary Bass Radiator technology in the development of our current line of loudspeakers and Powered Subwoofers, proving our company-wide dedication to the deepest, most thrilling, realistically musical bass response possible.

SL 2000 Silver Coil Dome Tweeter

Polk Audio engineers worked with the Johns Hopkins University Center for Non-Destructive Testing, utilized Laser Interferometry Technology, to test a vast number of tweeter designs and materials in their search for high frequency perfection. (Dynamic Balance Tuning Technology was a direct outgrowth of this fundamental audio research.) They developed a revolutionary dome design that would produce near-perfect motion without the sonic degradation of standing waves. Cooled by Ultra Low Viscosity (ULV) Magnetic Fluid, the SL2000 delivers astounding details and pinpoint imaging, without no fatigue, even at constantly tremendous volume levels. The accurate performance of every dome tweeter Polk Audio has designed and engineered since the SRS Series has benefitted from this fundamental research.

High Efficiency Amplifier Compatibility

The SRS Series was designed and engineered to be driven well by practically any electronics available at the time, even the most modestly-powered amplifer or receiver. They present an "easy load." We recommend that a high quality amplifier or receiver of at least 50 watts per channel be used for the best performance. (If you're using separate mono amplifiers without a common ground, Polk's AI-1 interface is available separately to ensure a proper connection.) You don't need an expensive high powered audiophile rig to enjoy the warm, clear, realism of the SRS Series. 

Bi-Amp Capability

For even greater dynamic range and lower distortion, the SRS loudspeakers may be connected for Bi-Amplification using the two sets of inputs provided on each loudspeaker. No electronic crossover is necessary. When you use two different amplifiers to reproduce the high and low frequencies separately, SRS loudspeakers achieve their greatest sonic potential.

"Bass-Brace" & Floor Spike Floor-Coupling Hardware Included

To enhance the full impact and dimension of Polk's low frequency performance, SRS Series speakers may be physically coupled to your listening room wall or floor with their specially designed "Bass Brace" hardware or Spiked Feet in place.

Driver Complement

Tweeter
Quantity
Diameter1" (2.54cm) 
TypePolk SL2000 silver coil dome tweeters 
Midrange
Quantity
Diameter6 1/2" (16.51cm) 
Typetri-laminate polymer bass-midrange drivers 
Subwoofer
Quantity
Diameter12" (30.48cm) 
Typeplanar fluid-coupled subwoofer 

Electrical

Maximum SPL120 dB
Total Frequency Response15 Hz - 26kHz 
Nominal Impedance4 ohms
Efficiency92 dB
Recommended Amplifier Power10-500 watts per channel

Amplifier Specs

Maximum SPL120 dB
220V AvailabilityNo 
Amplifier TypeNone 

Dimensions

Cabinet Dimensions
Height39 1/2" (100.33cm) 
Width16" (40.64cm) 
Depth12" (30.48cm) 
Product Weight (each)65 pounds

Shipping

Unit of Measureeach 
Included AccessoriesSDA interconnect cable 

Warranty

Speaker Warranty5 years parts and labor (original purchaser) 

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.

SDA 2A Media

SDA 2A Literature

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SDA 2A Accessories