Very Heavy (20lb!) Polk Bookshelf Speakers RT35

Polk’s RT35 is a solid two-way bookshelf design incorporating Polk’s 6 1/2″ polymer/mineral-composite woofer and 1″ shielded polymer-dome tweeter. The speaker’s walls are fabricated from 3/4″ MDF, and the front baffle is a full 1″ thick, while the rear baffle is of an injection-molded mineral-filled polymer. Polk has also incorporated several proprietary technologies in the RT35.

Beginning in 1988, Polk began a long-term research project in partnership with Johns Hopkins University. This resulted in a new research tool that enabled Polk to view and analyze the entire vibrating surface of a speaker driver. In particular, Polk was able to see and understand the resonance that develops on loudspeaker cones as they move. Modal resonance is a major cause of frequency-response aberrations and other distortions in loudspeakers. The result of this analysis, Polk’s Dynamic Balance[R] technology, allows the company to design drive units with, in their words, “unusual clarity, detail and extension.”

Additionally, Polk’s Power Port[TM] technology refers to the company’s method of reducing air turbulence at the mouth of the bass port. Polk says that by reducing this turbulence, in addition to reducing “chuffing” noise, they actually improve bass efficiency by a full 3dB while reducing distortion. The Power Port itself consists of a “cone” at the mouth of the port that occupies the space between the port (pointing into the port’s mouth) and a supporting plinth. According to Polk, “the cone promotes laminar airflow and the ever-increasing cross-sectional area of the space mimics a very long flared port.” Conveniently, the port’s plinth also acts as a handy wall-mount bracket.

Perhaps the most interesting of the technologies incorporated is the Acoustic Resonance Control system. Simply put, this is a method of counteracting identified internal box resonance’s by designing a port system tuned to those same resonance frequencies — but out of phase. As the out-of-phase output from the ports combine with the resonance of the speaker system, the two cancel each other out. Polk adds: “The audible results are greater midrange clarity and detail with noticeably more natural and accurate reproduction of vocals. Imaging is also markedly improved, [and] the speaker exhibits superior localization stability and image depth.”

Connection to the RT35 is via a single pair of gold-plated five-way binding posts. Finish is a black wood-grain-vinyl, but the front baffle is a pebble-grain black vinyl — quite handsome actually.

Polk states a frequency response with -3dB points of 50Hz and 23kHz. Crossover is accomplished by second-order high- and low-pass filters at 2kHz. Sensitivity is stated as 90dB, and nominal impedance is said to be compatible with 8-ohm outputs.

The speakers measure 15″H x 8″W x 12″D and weigh 20 pounds each.

The RT35’s retailed for $399 USD. Asking just $245 for these excellent quality speakers.