Polk

Baltimore garage startup to American speaker institution

History

Polk Audio was founded in Baltimore, Maryland in 1972 by three Johns Hopkins University graduates: Matthew Polk, George Klopfer, and Sandy Gross. The company started in a garage with a mission to produce quality loudspeakers at affordable prices. The Monitor series (1970s-1980s) established Polk's reputation. The Monitor 7, Monitor 10, and Monitor 12 offered excellent performance per dollar with innovative driver designs and solid construction. Polk pioneered several technologies: - SDA (Stereo Dimensional Array) - Crosstalk cancellation for improved imaging - Dynamic Balance - Driver design optimization - Power Port - Bass reflex enhancement The 1980s brought the flagship SDA-SRS series with elaborate crosstalk cancellation systems. The RTA series offered sophisticated crossover networks and premium drivers. In the 1990s and 2000s, Polk expanded into home theater, car audio, and outdoor speakers while maintaining its core speaker business. The company was acquired by DEI Holdings in 2006 and later became part of Sound United.

Key Facts

Fact	Detail
Founded	1972, Baltimore, Maryland
Founders	Polk, Klopfer, Gross
First Product	Monitor series speakers
Key Innovation	SDA technology
Best Known	Monitor 7, 10, SDA series
Current Status	Part of Sound United

Legendary Products

Polk Monitor 10 (1970s-1980s)

Polk's breakthrough product. The Monitor 10 used two 6.5" woofers, a passive radiator, and a dome tweeter to deliver exceptional bass and smooth highs at an affordable price.

Polk Monitor 7 (1970s-1980s)

A smaller sibling to the Monitor 10 that became equally popular. The Monitor 7 offered much of the Monitor 10's performance in a more compact cabinet.

Polk SDA-1A (1980s)

The flagship of Polk's SDA series, featuring elaborate crosstalk cancellation for holographic imaging. The SDA-1A represented Polk's ultimate statement in stereo reproduction.

Polk RTA-15TL (1990s)

A high-end speaker from Polk's RTA series, featuring sophisticated crossover networks and premium drivers in an elegant cabinet.

Sound Signature

Polk speakers deliver a big, room-filling American sound with bass punch that belies their modest pricing. The Monitor series uses multiple smaller woofers and passive radiators to produce low-frequency output that is both powerful and surprisingly well-controlled. The overall presentation is warm and engaging — these are speakers that want to entertain you, with a wide dispersion pattern that creates a large, immersive listening area rather than a narrow sweet spot.

The SDA (Stereo Dimensional Array) technology is where Polk gets genuinely revolutionary. By using an interconnect cable between speakers to cancel acoustic crosstalk, SDA speakers create a soundstage that is dramatically wider and more three-dimensional than conventional stereo. The effect with well-recorded material is startling — instruments seem to occupy space well beyond the physical boundaries of the speakers. It is a technology that deserves more recognition than it typically receives.

Collecting Polk

The Monitor 10 is Polk's breakthrough product and the collector's starting point — its dual 6.5-inch woofers, passive radiator, and dome tweeter deliver performance that routinely surprises listeners who associate the brand only with budget audio. The Monitor 7 offers much of the same magic in a more compact package. First-generation Monitor series speakers from the late 1970s are the most sought after, identifiable by their specific driver configurations and cabinet construction.

The SDA-1A is the crown jewel of Polk collecting — a large, ambitious speaker that delivers a listening experience unlike anything else at its price point. Working SDA systems with intact interconnect cables are essential (the SDA effect requires the cable connection between speakers). The RTA-15TL from the 1990s represents Polk's move upmarket with premium drivers and sophisticated crossovers. When buying vintage Polk speakers, check the SL2000 tweeters carefully — these are a known weak point that may need replacement, and aftermarket options are available.

Competitors & Comparisons

Polk vs Boston Acoustics: Both American; similar positioning Polk vs Infinity: Both value brands; different approaches Polk vs JBL: JBL more professional; Polk more consumer

Models

Amplifiers

SDA SRS-2 (1986) — An innovative signal-referenced stereo headphone amplifier and processor from Polk Audio, designed to enhance spatial imaging and realism in headphone listening.

Speakers

11T — Polk 11T (c. 1988–1993) — late-'80s Polk tower speaker advertised as the RTA 11t at $449.95 each, 250W handling, 90dB. Little documented beyond period ads.
12B — Polk RTA 12B floor-standing speaker (circa 1981–1982). Award-winning top model in the Audio Monitor Series, 4-ohm, 75 lbs, walnut veneer.
Audio RM-2000 — Polk Audio RM-2000 (c.1993): three-piece sub/sat system, 3/4-inch dome tweeter, 10-inch sub-bass radiator, 125W, $750 MSRP. Little else documented.
Audio RM-3000 — Polk Audio RM-3000 three-piece speaker system from the early 1990s; a 1990 test report and Polk's award-winning ads document this little-known model.
AUDIO-MONITOR 15T (Military) (1991) — Rare military-spec variant of the Polk AUDIO-MONITOR 15T, built for durability and performance in demanding environments.
AUDIO-MONITOR 5JR (1984) — Compact bookshelf speaker from Polk Audio's acclaimed AM series, known for balanced sound and excellent value in the mid-1980s.
CS-100 — Polk CS-100 center channel speaker — compact half-trapezoid cabinet, dual small woofers and dome tweeter, sold cheap or free in early-'90s Polk promotions.
CS-250S — Polk CS-250S center-channel speaker, reviewed in Audio (July 1995) at $299 for affordable home theater. Little else is documented.
LS-70 — The Polk LS-70 is a little-documented vintage speaker. No verified specs survive; period archive clippings actually concern the larger LS 90.
LS-90 — Polk LS-90, Polk's 1994 flagship loudspeaker. A 1994 Audio review details a 12-inch-wide cabinet, four 6.5-inch drivers, and a 26 kHz top end.
Model 10 (1976) — Polk Model 10 (1976) — the Monitor Series bookshelf that dealers sold as simply a steal at $209.95. Early Polk value hi-fi with a Spendor-comparison pedigree.
Model 9 (1973) — The original Polk speaker, the Model 9 from 1973, launched a legendary audio brand with its innovative design and accessible high-fidelity sound.
Monitor 10 Series II (1990) — Compact bookshelf speaker from Polk's iconic Monitor series, known for balanced sound and value in the early 1990s. Includes detailed specs.
Monitor 10A (1979) — A compact bookshelf speaker from Polk's legendary Monitor series, known for balanced sound and innovative design in the early 1980s.
Monitor 4.6 Series 2 (1990) — Compact bookshelf speaker from Polk's acclaimed Monitor series, known for balanced sound and innovative design in the early 1990s.
Monitor 4A (1984) — A compact bookshelf speaker from Polk's legendary Monitor series, the monitor 4A (1984) delivers balanced sound with excellent value for vintage audio enthusiasts.
Monitor 5B (1984) — Compact bookshelf speaker from Polk's legendary Monitor series, known for balanced sound and excellent value in the mid-1980s.
Monitor 7 (1977) — A compact bookshelf speaker from Polk's original Monitor series, known for balanced sound and solid build during the late 1970s and early 1980s.
Monitor 7 Series II (1990) — Compact bookshelf speaker from Polk's acclaimed Monitor Series, known for balanced sound and value in the early '90s. This page has the complete spec table.
Monitor 7A (1977) — A classic bookshelf speaker from Polk's early Monitor series, known for its balanced sound and durable design. Covers full specifications.
Monitor 7C (1979) — A compact bookshelf speaker from Polk's original Monitor series, known for its balanced sound and innovative design for the late 1970s.
Monitor 9W (1976) — A compact, bass-reflex bookshelf speaker from Polk's legendary Monitor series, known for balanced sound and reliable performance in small to mid-sized rooms.
MW-6512 — Little is documented about the Polk MW-6512. What the record shows is essentially a spec block that ran in Polk's own advertising around 1990–1992: Audio.
PSW-300 — Polk PSW-300 powered subwoofer, late 1990s. A 1997 Audio review measured clean bass to 32 Hz; documented mostly through that review and a 1996 ad.
PSW10 — Polk PSW10 powered subwoofer delivers 50W bass from 40Hz, weighs 25 lbs — valued for flexibility but known for port noise and amp failures.
RM-2000 — The Polk RM-2000, a little-documented three-piece sub/sat speaker system from 1993, listed at $750 MSRP. Find production dates here.
RTA-11 — Polk RTA-11 (c. 1982) — a little-documented floor-standing speaker, cited in Audio magazine as an affordable version of the award-winning RTA-12B.
RTA-11T — Polk RTA-11T tower speaker, late 1980s–early 1990s. Little documented beyond period ads claiming 250W power handling and 90dB sensitivity.
RTA-12 (1979) — The Polk Audio RTA-12 (1979–1984) was the brand's first time-aligned speaker, featuring a 12-inch passive radiator and FFT-designed crossover.
RTA-12B — Polk RTA-12B: floor-standing 4-ohm speaker, top of Polk's Audio Monitor Series; 1982 Hirsch-Houck review, Hi Fi Grand Prix Award winner.
RTA-12C (1984) — Polk RTA-12C floor-standing speaker, flagship of the Monitor Series 1984–1988, $479.95 each per period Polk advertising; little else documented.
SDA-1A (1985) — A revolutionary stereo speaker system using time-delayed crosstalk cancellation for a holographic soundstage. Find the complete spec table here.
SDA-2B (Real Wood) (1989) — A refined version of Polk's legendary SDA series, the SDA-2B in real wood finish offers spatial imaging and detailed sound in a classic bookshelf design.
SDA-2B (Studio) (1988) — A refined version of Polk's legendary SDA series, the SDA-2B Studio delivers coherent, spacious sound using the innovative Time Alignment and Stereodipole technologies.
SDA-2B CRS+ (1989) — A rare real-wood finish version of the legendary Polk SDA-2B CRS+, featuring Stereo Dimensional Array technology for holographic sound staging.
SDA-CRS (1984) — Polk SDA-CRS (1984): compact SDA Stereo Dimension Array bookshelf speaker system, $395 each, reviewed in HI-Fi-Stereo-Buyers.
SL-2500 — Polk SL-2500: the 1-inch dome tweeter fitted across Polk's Monitor Series 2 speakers, c. 1990–91. Shared tech with the SL 3000 of the flagship SRS line.
SRS — Polk SRS (1985–1993) — Polk's flagship floor-standing tower, known for push-push woofers and time-aligned drivers. Confusingly also a 1985 satellite/sub system.

Unknown

295 — Obscure Polk Audio model with no confirmed documentation. Identity, era, and specifications are unknown. Possibly a price-point reference rather than a product model number.
MM-6902 — Polk MM-6902 Mobile Monitor car audio speaker – little documented; period ads show 1987 price of $114.90 each and series relation to MM 6900 award winner.

Other Models

AUDIO SRS 12TL — Polk Audio SRS 12TL (late 1980s): 63-inch tall, 180 lb flagship towers with SDA crosstalk cancellation. A towering statement of vintage high-end ambition.
audio-5jr — Polk Audio 5jr (1988) — compact two-way bookshelf speaker, 100W handling, 6-ohm impedance, 49Hz-28kHz response. Little-documented model with positive owner reports.
monitor-5jr — Polk Monitor 5Jr — the cheapest of Polk's 1980s Monitor Series, pitched as the best speaker of its price. Original prices ran roughly $150–$170 each.
RT-2000P — Polk Audio RT-2000p tower speaker with built-in 200W powered subwoofer, two 8-inch woofers, $1,900/pair. Reviewed by Audio, May 1998.
RTA-15T — Polk RTA-15T — SRS-derived line source tower with SL3000 tri-laminate tweeter and dual 10-inch sub-bass radiators, front and rear.
sda1 — A pair of stereo loudspeakers from Polk Audio featuring early crosstalk cancellation technology, sold for $995 per pair in 1984.
SRS 23TL — A 10-driver loudspeaker system from Polk’s flagship SDA-SRS series, using crosstalk cancellation for enhanced stereo imaging.