Polk Audio LSi M 702 F/X Surround Effects Speaker Pair

Driver technology

Performance Objectives Of The Polk Audio Slim Series Loudspeakers:
The lsim series loudspeakers are polk audio's best high-performance loudspeaker. Polk audio designed the lsim series loudspeakers to create a sound that virtually transports you to the scene of the recorded performance. It was engineered & created with the following performance objectives in mind.

  • Pleasing tonality, even during extended listening at performance levels.
  • Crisp, lifelike impulses, transients & coherent detail without any unnatural ringing or decay.
  • Natural reproduction of complex low frequency instruments & special effects.
  • Uniform sonic representation within the listening area & immersive spatial impression.
  • Reproduce concert/theater levels while maintaining linearity and accuracy.
  • Compatibility with a wide array of electronics both past, present & future.
  • Work as promised for many years of enjoyment (5 year parts & labor warranty).

Dynamic Balance:

  • Dynamic balance is a proprietary polk audio technology using laser imaging to determine what combination of speaker materials create the least amount of resonance.
  • Eliminating resonance in speakers results in a wide, smooth response, & low distortion.


3-Way Driver System:

  • The polk audio lsim series surround loudspeakers employ a 3-way driver system for crisp, detailed highs; natural, lifelike midrange; and accurate, dynamic midbass.
  • The surround loudspeakers house a 1" (diameter) dynamic balance enhanced ring radiator tweeter, a 3.25" (diameter) dynamic balance super cell aerated polypropylene cone midrange driver, & a 6.5" (diameter) dynamic balance super cell aerated polypropylene cone midbass woofer.


Enhanced Ring Radiator Tweeter:

  • The ring radiator tweeter was a vital element in the success of polk audio's original lsi series.
  • Polk audio engineers have made some nuanced improvements in the design of this tweeter.
  • First, they reshaped the tweeter's bullet-shaped phase plug, allowing it to move farther out of the baffle, improving dispersion and eliminating horn-loading.
  • Next, they opened up the tweeter's face-plate, then redesigned the tweeter's diaphragm roll to make it more efficient and improve dispersion even more.
  • Finally, they gave the new ring radiator tweeter its own tuned enclosure (dynamic sonic engine).
  • This new ring radiator tweeter boasts higher power handling, extended dynamic range, improved dispersion and extended top-end response.

Super Cell Aerated Polypropylene (App) Cone Woofer:

  • If the perfect cone material is lightweight (for faster, more efficient action) and stiff (for less distortion-causing flex), with enough internal damping to suppress and offset any limitations of its lightweight stiffness, then the super cell app cone material is about as perfect as cone material gets.
  • Aerated polypropylene (app) is a mineral-filled polypropylene material that's been "Puffed up" with injected air to form a honey-comb structure.
  • Polk audio's original app cone approached the ideal balance of lightweight stiffness with high damping, along with good resistance to moisture, uv and temperature extremes.
  • Next generation lsim series loudspeakers employ polk audio's next generation of app super cell.
  • In super cell app, the "Puffed cells" are larger, for a thicker cone material that actually has less mass than the original app material.
  • Super cell app has larger cells, for lighter weight and more inherent damping, plus uncompromised stiffness, for unsurpassed transient response and resonance suppression.

Butyl Rubber Surrounds:

  • Durable, soft, injection-molded butyl rubber surrounds are tuned to absorb and suppress unwanted cone resonances.
  • Polk audio's butyl rubber material is impervious to uv, extreme temps & humidity, for a lifetime of smooth, reliable sound.

Extended Linear Motion Voice Coils:

  • Allowing lots of movement in a limited space, elm voice coils power the lsim series speaker's mid-range & mid-woofer drivers to extend their higher-frequency response with much less impedance.

Cast Aluminum Baskets:

  • These lightweight, cast aluminum baskets provide a rigid structure for precise alignment of the speaker's active parts, for flat response & low distortion, with no mechanical resonances or ringing.
  • The open design provides ample venting for unobstructed linear movement.

Orth Crossovers:

  • The polk audio lsim series surround speakers employ proprietary engineering, designed and patented by polk audio to maintain a lower order crossover design & increase power handling.
  • Orth crossovers feature mylar/polypropylene capacitors for sparkling highs & air core inductors for superior transparency.
  • Notch filters and sophisticated zobel circuits smooth the impedance curve of the system for more efficiency & better high frequency response.
  • Tweeter/midrange crossover: 2.4 khz 18 db/oct
  • Midrange/midbass crossover: 240 hz 12 db/oct

Timbre-Match Series:

  • You can achieve incredible realism & seamless surround effects when you build a complete polk audio lsim series speaker system.
  • All lsim series speaker models feature the same components & tuning for perfect timbre-matching.

Frequency Response Note:

  • The overall frequency response is 45hz to 40khz & the -3db frequency response is 55hz to 30khz.

Enclosure Design

High-Gloss Black Wood Veneer:

  • The polk audio lsim loudspeakers are finished in a high-gloss black, furniture-grade wood veneer.

MDF Enclosure:

  • The enclosure is an integral part of the sound design of the polk audio lsim series loudspeakers.
  • All lsim cabinets are made of .75" mdf, with wide-radius baffles of robust 1.25" mdf.
  • Substantial internal bracing (each driver has its own separate non-parallel chamber) increases efficiency and banishes internal resonances & standing waves, for high power handling and incredible smoothness.
  • Wide-radius baffles, along with zero-diffraction magnetic grilles, help stabilize imaging for a very wide, well-defined soundstage.

Dynamic Sonic Engine (DSE):

  • At the heart of the polk audio lsim series surround loudspeakers is an enclosure-within-the-enclosure design (known as the dynamic sonic engine) that houses the mid-range driver & the ring radiator tweeter.
  • Molded into one rigid piece, the dse enclosure tapers to a "Turbine" that reduces back-wave reflections.
  • The dse combines its two speakers in an aligned, optimized array for wide, uniform dispersion in the critical 200hz-2khz midrange, improving transient response.
  • The combination delivers exact timbre-matching, improved high-frequency dispersion and greater horizontal off-axis response.

Note:

  • The ring radiator tweeter & midrange driver are housed in a separate internal sealed enclosure from the ported enclosure which houses the midbass woofer.

Powerport Bass Venting:

  • Powerport bass venting is a patented polk audio technology that uses a specially designed "Cone" at the mouth of the bass port to direct moving air as it exits the port.
  • Air moving out of a bass port creates turbulence, which can result in boomy distortion & "Port noise", especially at high volume.
  • This distortion can cause bass output losses up to 3db, wasting lots of amp power.
  • To eliminate bass-stealing turbulence at the mouth of the port, polk audio engineers designed the powerport.
  • It's unique shape promotes "Laminar" airflow even in short tube ports by mimicking the properties of longer, flared port openings.
  • No turbulence means no wasted power, which means more efficient bass response.

Zero-Diffraction Magnetic Grille:

  • The super thin (1mm), zero-diffraction grille has no measurable effect on the speaker's response.
  • Completely unobtrusive, stylishly sheer; the grille locks into place magnetically.

Connections

Gold-Plated Binding Posts:

  • Each surround loudspeaker has one set of gold-plated binding posts.
  • The binding posts will accept bare wire (16-12 awg), pin connectors, spade connectors, & banana plugs (single only).

Color-Coded:

  • The surround speakers' binding posts are color-coded (red/black) for easy identification between positive & negative.

Mounting Options

Keyhole Slots For Wall-Mounting:

  • The lsim series surround loudspeakers have built-in dual keyhole slots for wall mounting (stud-mounting recommended).
  • The dual keyhole slots are spaced 12" apart (a mounting template is provided).
  • The surround loudspeakers can be hung either on side walls or rear walls. The loudspeakers should be mounted 6-8' off the floor.
  • If you're setting up a 7.1 system, mount the surround back left & surround back right loudspeakers at the same height as the surround left & surround right loudspeakers.

Note:

  • The lsim series surround loudspeakers should be oriented so that the dynamic sonic engine (3 1/4" mid-range / 1" ring radiator tweeter) points toward your listening area.
  • Therefore, the surround loudspeaker that would serve as the right surround on a sidewall will become the left surround on a rear wall.

Wall Distance Switch:

  • The lsim series surround loudspeakers feature a wall distance switch located on the baffle underneath the grille.
  • If position limitations demand that the surround loudspeakers be mounted closer than 2' from side walls or ceiling, the proximity of the surface can result in a response "Bump" between 50 & 200hz.
  • This can cause the loudspeakers to sound "Boomy".
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