Tower Speaker Reviews

Polk Audio Legend L800 Loudspeaker Review

Al Griffin  |  Oct 23, 2019


Performance
Build Quality
Value
PRICE $5,998/pair

AT A GLANCE
Plus
Enveloping soundstage from SDA-Pro tech
Dynamic, full-range sound
Flush-mounted elevation module option
Minus
Somewhat bulky cabinet design
Requires SDA-Pro interconnect cable

THE VERDICT
SDA-Pro, the latest refinement of Polk Audio's proprietary tech, elevates the performance of its impressive flagship speaker.

Many years ago (the early 1980s, to be precise), Polk Audio produced the first speakers to feature a technology it had developed called SDA (Stereo Dimensional Array). The idea behind SDA was to eliminate a problem called interaural crosstalk that's a necessary artifact of typical two-channel speaker configurations. Basically put, when listening in stereo, your left/ right ears hear not just sound emanating from the respective left/right speakers, but sound coming from the other speaker as well. According to Polk Audio, this has a constricting effect on the presentation, with the width, height, and depth of the stereo image coming across as a pale representation of what's actually contained on the recording.

The original SDA models, a number of which were reviewed by Sound & Vision magazine's predecessor, Stereo Review, dealt with the issue of interaural crosstalk in a purely acoustic way by using a second set of drivers (the Dimension Array) on each speaker. These directed a "cancellation" signal—essentially, an out-of-phase version of the sound being emitted by the opposite speaker. The effect of this was to maintain the stereo separation that exists in the recorded program through the full audio component chain direct to your ears, roughly similar to the way that headphones function.

For its newest line of speakers, the Legend series, Polk Audio decided to revive SDA and incorporate it in the top-end L800 floorstanding model ($2,999/each). The other speakers in the Legend series, which consists of a smaller floorstander, two bookshelf models, a center speaker, and Atmos Elevation modules, do not feature the technology. Not only did Polk Audio bring SDA back for its Legend series flagship, but they made numerous refinements, re-badging it as SDA-Pro.

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The specific tweaks made for SDA-Pro include a 15-degree angle to the speaker baffles for both the regular and Dimension driver arrays. This eliminates any need for speaker toe-in since it's already built into the design. It also reduces cabinet width in comparison with earlier SDA models. Unlike earlier designs, the L800's Dimension Array uses a tweeter to cover the extended bandwidth of the cancellation signal, though that signal is rolled off above 10kHz. Finally, SDA-Pro incorporates a Head Shadow Filter to account for the physical effects of

the listener's head and face. While Polk Audio still uses a purely acoustic approach for SDA-Pro with no digital signal processing, the Dimension Array's crossover is EQ'd to optimize the cancellation signal, with filtering normalized for the head shadow created by an average listener.

SDA-Pro isn't the only thing that the L800 brings to the party. The tower's substantial 17.9 x 48.6 x 17.4-inch (WxHxD) cabinet boasts exceptional build quality and uses real wood veneer finishes. My review sample was clad in a Brown Walnut that nicely matched my living room's interior; the other available option is Black Oak. Magnetically attached black cloth speaker grilles are provided, though Polk Audio suggested that I leave them off for my review.

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The L800's dual driver array features the company's new high-definition Pinnacle ring radiator tweeter. An evolution of the tweeter found in the company's previous LSiM Series, it pairs a 1-inch ring with waveguides located at the center and outer edges. According to Polk Audio, the waveguides maximize dispersion and also smooth response by eliminating break-up modes typically generated by a central dome. A damped cavity behind the tweeter also helps to reduce resonances and "ringing" at 2.5kHz.

A 6.5-inch Turbine midrange driver developed for the Legend Series features a foam-core polymer-injected cone and an asymmetric geometry, both of which work to smooth out vibra- tional modes and resonances. This is located on the angled upper section of the L800's baffle alongside the tweeter, while the tower's lower section features a pair of 10-inch woofers.

The L800 features a bottom- mounted "Power Port" that maximizes cabinet space for increased air flow and reduced turbulence compared with conventional front or rear- mounted ports. Power Port, too, gets a refresh in the Legend Series, with redesigned port flare geometry meant to further increase bass output and reduce distortion.

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Both the L800 and L600 Legend towers feature a top- mounted panel that can be removed to install the company's optional L900 height module speaker ($599/pair) for playback of Atmos/DTS:X and virtualized soundtracks. The module features a 0.75-inch version of the Pinnacle ring radiator tweeter and 4-inch Turbine Cone midrange/bass driver in a horizontal alignment that's said to deliver a large sweet spot with immersive audio. Unlike some other elevation speakers that I've seen, Polk Audio's option for the Legend towers offers an "invisible" solution, with the flush-mounted modules literally disappearing into the speaker's top surface.

The L800's rear panel input connections include dual gold-plated five-way binding posts with jumpers that can be removed for bi-amping. Another set of binding posts is provided for a height speaker input, and there's a socket for the SDA-Pro cable that runs between the speakers and delivers the crosstalk-canceling signal to the left and right Dimension arrays, respectively. Each L800 tower comes with a 15-foot SDA-Pro cable, and while a single length should suffice for most setups, the two can be daisy chained for installations where the cable gets snaked through a wall or cabinet.

Setup
Setup of the L800 towers didn't follow nearly the same template I'm used to when positioning speakers for best sound in my listening room. Not only is no toe-in required, but Polk Audio recommends that you place the towers 6-8-foot from one another—an unusually close distance. Such tight positioning ensures you are getting maximum effect from SDA-Pro, and it also reduces the impact of side walls and other reflective surfaces on the sound.

To confirm that the speakers were correctly aligned for my review, Polk Audio sent Scott Orth, the company's Head of Audio and Acoustics, to assist with setup. Using various SDA-Pro-friendly music tracks Polk Audio engineers have culled from years of experience working with the technology, Scott painstakingly tweaked positioning, with the final result finding the towers approximately 6 feet from each other, five feet in from either side wall, and about 1 foot out from the back wall. The listening seat on my sofa, meanwhile, was located about 8 feet away from the speakers.

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COMPANY INFO
Polk Audio
(800) 377-POLK
polkaudio.com
ARTICLE CONTENTS

COMMENTS
Mako2019's picture
Submitted by Mako2019 on October 24, 2019 - 9:32am

From the Article: "Scott painstakingly tweaked positioning, with the final result finding the towers approximately 6 feet from each other, five feet in from either side wall, and about 1 foot out from the back wall. The listening seat on my sofa, meanwhile, was located about 8 feet away from the speakers"

My own listening environment dictates the speakers must be about 11 feet apart and 13 feet in front of the primary listening position. I wonder if these speakers so position sensitive that I would loose much in terms of SDA-Pro benefits and sound stage.

greck's picture
Submitted by greck on October 24, 2019 - 12:41pm

These look like nice speakers but the BACCH4mac is a much more flexible and more advanced version of crosstalk cancelation. I have the BACCH4mac and cannot day enough good things about it.

brenro's picture
Submitted by brenro on October 24, 2019 - 4:05pm

At the same price as Sandy's Goldenear Triton One R.

drny's picture
Submitted by drny on October 24, 2019 - 5:11pm

The room must be enclosed on both sides adjacent to the speakers, and they indeed need to be located substantially away from the side walls and relatively close to each other. Otherwise you will not have the desire differential affect.
I'm sure they will delivered, under the right conditions.

wgapel's picture
Submitted by wgapel on December 5, 2019 - 3:55pm

Is the sweet spot larger or smaller than speakers without this tech? In other words is this a one person speaker or can multiple people sit side by side and still hear the benefits of SDA-PRO?

sahmen's picture
Submitted by sahmen on December 27, 2019 - 11:03pm

Is it known whether these speakers are timbre matched with other series of speakers in the Polk lines? I have a large variety of LSIM series speakers, and I am wondering whether I can match a pair of L800s with some of those. That would save me some money, of course,

hk2000's picture
Submitted by hk2000 on January 27, 2020 - 3:53am

This is a flawed concept because if you were listening to the sound of a band on a stage, both of your ears will hear the sounds emanating from anywhere on the stage. To say you have to eliminate the sound of the right speaker from the left ear and vice-versa is ridiculous, and unnecessary. In fact our ability to perceive three dimensional sound is predicated on the both ears hearing all sounds around us, then our brains extrapolate the precise location from where the sound is coming.
I for one wouldn't buy them even if I could afford them.

ChrisTexan's picture
Submitted by ChrisTexan on May 14, 2020 - 9:54am

It's to eliminate the crosstalk that can distort the sound. You will still hear sound from both right and left speakers, but the SDA is to reduce/eliminate the lobing/interference/reinforcement (incoherency) affect of an artificial point source projected from 2 speakers. (And other such auditory problems).
In real life, if a piano is 30-degrees (30*) to your right, all the sound (other than ambient reflections) is coming from 30* to the right. If a singer is front-center, all the sound is coming from front-center.
In speaker terms, a portion of the sound for either case, is coming from both speakers angles (say 10* right/left position to your listening position). The mix determines how it "sounds" to be coming to you. With headphones on, the mix is perfect, because there is no reinforcement or cancellation from source (ear speakers) to your listening position. As a mix engineer, they can swing the positioning at will from each track source. When translated to open-air speakers, listener and speaker positioning, distance from them, toe-in, everything alters the signal from output to listening position. The SDA is designed to remove some of the incoherency of the waves mixing prior to reaching your position, resulting in more pure (more "headphone like") sourcing to each of your ears, NOT to cancel out the right/left balances from the mix. Quite the opposite, it's intended to deliver a purer sound to each of your ears from right and left sources. Whether it works or not, or is needed or not, that's up for debate I suppose, but ultimately it's just to reduce unintended incoherence, so that purer left/right signals, as mixed, reach your listening position. (All my opinion, but hopefully the headphone comparison helps with the conceptual goal).

hk2000's picture
Submitted by hk2000 on May 14, 2020 - 5:48pm

Well I was responding to the statement made by the writer. you're explanation is no more than a fancy way of saying just about the same thing. I for one consider listening via 'phones an inferior option and takes away a lot from the live experience most audiophiles endeavor to achieve with their setups. My objections apply equally to listening through headphones.

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