 Polk
Audio LSi15 Loudspeakers
Napoleon once said, "God is on the side with the most
cannon." What he meant, of course, was that given forces with equal will to win,
fortune favors the one with the most resources. It's the same in audio: A successful
company that's dedicated to producing a quality product has access to resources that an
equally dedicated small company simply doesn't.
That doesn't mean that small companies can't produce better
speakers than the big guys -- many do -- they just have to want to more than the
big guys. (And again, many do.)
But when you can manufacture your own drivers and spend
many thousands of dollars researching the laminar flow characteristics of port behavior,
you're well ahead of the builder with a table saw and a parts catalog, no matter how
dedicated he or she might be. And that's exactly where Polk finds itself these days --
blessed by success with resources smaller companies can only fantasize about.
For audiophiles of a certain age, Matthew Polk's designs
came along at just the right time for us to graduate from our aging Advents and ARs to a
newer, more efficient, good-sounding loudspeaker. Some of the early models were almost
iconic among impecunious but discerning listeners.
Then the nascent high end came along and audiophiles no
longer trusted the big mainstream companies. And frankly, a lot of the mainstream
companies seemed to lose sight of the properties that differentiated them in the first
place, and began to crank out "product" -- all too frequently with
identical-sounding models at price points separated from one another by as little as $10.
That may or may not have been the case at Polk -- I can't
say since I don't think I heard any Polk speakers between 1984 and 1996 -- but that
certainly seemed to be the general audiophile opinion. And sometimes, perception is
reality.
But in 1996, the corporate image of Matthew Polk in a white
lab coat disappeared and one began to hear things. Stereophile's publisher, Larry
Archibald, returning to Santa Fe from a trip back East, casually mentioned that the
company was producing some impressive speakers. And the Internet suddenly seemed awash in
Polk queries.
So I auditioned the $330/pair, two-way RT5s and was blown
away by their timbral honesty and lack of fussiness. Since then, Polk has seemingly been
on a roll, producing many models that combined great sound with extreme affordability.
Even so, I was not completely prepared for the LSi15, which combines honesty and
accuracy with a list price that seems as though it must be a misprint ($1740/pair).
Glory is precious forever
The LSi15's cabinet is quite narrow, but it's also
deep. This necessitates that the woofer be mounted on the cabinet's side rather than its
front. The omnidirectional radiation pattern of low bass means there's no sonic difference
between mounting the woofer on the side of the speaker and the front -- except that by
keeping the cabinet narrow, the LSi15 combines the imaging capabilities of a small
monitor speaker with the authority and power of a full-range speaker system.
The LSi15 sports four drivers -- a 1" fabric
tweeter, two 5.25" midrange drivers, and an 8" woofer -- in what the company
calls a Cascade Tapered Array design or a 3.5-way system. Midrange duties are split
between the two 5.25" drivers, with one driver rolling off its upper frequencies
before the other -- as a result, there's no lobing between the two at frequencies where
dispersion is restricted. The lower driver employs a low-pass filter at 200Hz, with a
12dB/octave slope, whereas the upper driver's low-pass filter is engaged at 2.4kHz, again
with a 12dB/octave slope. The tweeter employs an 18dB/octave high-pass filter at 2.4kHz.
The two 5.25" drivers both employ a 6dB/octave high-pass filter at 150Hz. The 8"
woofer's 12dB/octave low-pass filter also pivots at 150Hz. All active crossover components
are connected with 18-gauge oxygen-free copper wire.
 Polk's Ring Radiator Tweeter
is a remarkable design. It is supported at two pivot points in order to deliver flat
response while preserving detail and accuracy. Polk covers this driver in great detail on
its website and it's worth
reading.
The LSi15's special Polk-designed 5.5"
midrange/woofer employs a heavy-duty superstructure, as well as double magnets and Polk's
Dynamic Balance construction technique, which is said to keep the driver from distorting
due to undamped internal resonances.
The LSi15 also employs Polk's patented Power Port,
which consists of a tapered cone placed at the port's mouth. The cone promotes laminar
airflow, and its flared cross-section reduces turbulence at the mouth and increases bass
efficiency (by about 2dB!).
The LSi15 sports two small "extra" ports
on the front panels. Polk calls this technique Acoustic Resonance Control. Tuned to the
panel's resonant frequency, these ports counteract the cabinet's natural internal
resonance. Silencing this resonance allows low-level detail to be more audible, Polk
claims, while preserving the natural sound and clarity of the drivers used.
The LSi15 's enclosure is
solidly constructed from internally braced 3/4" MDF, with 3/4" side panels clad
in high-gloss laminate. The cabinet is then sandwiched by two more side panels that serve
to further damp the enclosure and minimize box resonance. These side panels are finished
in real-wood veneer (ebony or cherry).
How rare, how precious is frivolity
The most amazing thing about the LSi15s is how
normal they are. They aren't too big and they certainly aren't all that small. At
slightly over $1700/pair, they aren't cheap, but that price point's far removed
from the Social-Security-number prices of the high-end's thoroughbreds. With 88dB
sensitivity and 4-ohm impedance, they aren't particularly hard to drive. Nor, with their
mirror-imaged driver array and side-firing woofer, are they hard to place. What they are,
mostly, is just right.
That's certainly true of the LSi15's
tonal balance. It actually produces a fair amount of deep bass (the speaker's rated -3dB
point is 32Hz), but it's completely in proportion to the rest of the speaker's range. In
fact, I'd say that initially the most attractive property this speaker possesses is its
top-to-bottom coherence. But, as I listened to disc after disc through the LSi15,
it began to dawn on me that I have seldom heard a flatter, less-colored top end. The bass
is what drew me in, but what kept me marveling hour after hour was the LSi15's
extremely real-sounding midrange through high frequencies. They give the speaker a deadpan
"just the facts, ma'am" quality that's the very antithesis of "hi-fi."
For acoustic music, the LSi15 is almost as
perfect a speaker as I've heard under $3500. Robert Silverman's lovely traversal of the
Beethoven piano sonatas (Beethoven: 32 Piano Sonatas [Orpheum Masters KSP 830])
sounded extremely present through the LSi15s. The high notes were limpid and
crisp and I was able to hear the far-too-early wall reflections that reveal just how small
a room the performances took place in.
But that's how the event sounded, so kudos to the
Polks for telling it like it is. The LSi15s also captured the bloom of the 9'
Bosendorfer and recreated that massive cabinet's room-filling sonorities to a T.
The Jerome Harris Quintet's Rendezvous [STPH 013]
actually surprised me through the LSi15s -- having produced, been present at the
recording, consulted on the mastering, and then used the recording as a reference tool for
years, you'd think that there'd be little concerning it that could surprise me. But such
is not the case. I've always felt that, for a record of a band led by a bassist, Rendezvous
sounded a tad light on its feet -- and it is. However, on a really good system (and played
back at the proper volume), it's a stunning recording -- full of punchy tonal colors and
great playing. (And if that sounds immodest, it's not -- as producer, all I really did was
conceive of the project and make sure the band showed up at the studio each day;
everything about the recording that works is the result of hard work on the part of the
players and recording engineer John Atkinson.)
Jerome Harris's woody, breathing acoustic bass guitar
purred and snapped through the Polks, riding along the dark intricacies of Billy
Drummond's athletic drumming. The two played together, but never in lockstep, creating a
spacious interplay that made Blue Heaven Studio's acoustic an integral element in the mix.
Over them, separately and together, Art Baron's trombone, Marty Ehrlich's alto sax, and
Steve Nelson's vibe swirled, reeled, and growled their lines like three old friends
arguing and kibitzing their way through another day spent together.
Oh, maybe the Polks lacked a slight amount of punch and
dynamic freedom at the very bottom end of their frequency range, but so does the recording
-- besides, bottom-end impact is cheap these days (as Polk's own PSW650 subwoofer clearly
demonstrates). Top-to-bottom balance, on the other hand, is not, and that the LSi15
has got in spades.
Played through my best two-channel setup (Ayre K-1x preamp,
Ayre V-5 power amp, Nu-Vista 3D CD player, Kimber KCAG interconnects and speaker cable),
the $1740/pair Polk LSi15s didn't quite live up to my all-time-reference Dynaudio
Evidence Temptations at $30,000/pair. The Temptations move a lot more air with their four
woofers per side, and they go deeper and have greater punch than the LSi15s. The
Polks don't quite have the big towers' seamless blend of lower midrange to bottom end,
either. And the big Dynaudios have an overall sense of authority that few rivals can
match. That's what the big bucks buy you, I reckon.
That the Polk LSi15s aren't embarrassed in such a
comparison is a tribute to the depth of engineering that produced them. They may be
lacking a few of the finer points resident in the very finest loudspeakers made, but they
don't miss by much. That's doggoned impressive.
A good name is like a precious ointment
Did I say, "For audiophiles of a certain age, Matthew
Polk's designs came along at just the right time"? That was a long time ago -- but
it's even truer today than it was almost 20 years ago.
In its current LSi series of loudspeakers -- and
most specifically in the LSi15 -- Polk is making the finest speakers it has ever
manufactured. The LSi15 is an honest design that benefits from the solid
engineering and construction that a huge company, such as Polk, can lavish on a project
when it sets its mind to it.
The LSi15 sounds balanced and natural, and it's more
accurate than many "exotic" speakers that cost a whole lot more. It is good
looking and easy to drive. You can certainly spend a lot more on a speaker -- and I'd be
the last to suggest that you couldn't buy a better-sounding loudspeaker -- but you'll have
to search long and hard before you find one as good as the Polk LSi15 anywhere near
its price.
...Wes Phillips
wes@onhifi.com
Polk Audio LSi15 Loudspeakers
Price: $869.95 USD each
Warranty: Five years parts and labor
Polk Audio
5601 Metro Drive
Baltimore, MD 21215
Phone: (410) 358-3600
Website: www.polkaudio.com
|
