Klipsch Forte IV Floorstanding Speaker (Single) at Vinyl Sound Toronto Canada

The Forte IV is a three-way horn-loaded floorstanding loudspeaker from Klipsch (Hope, Arkansas, USA), available at Vinyl Sound in Toronto, Canada. First introduced in 1985 as the most popular Klipsch model of its era, the Forte IV is the fourth generation of this Heritage Series icon, combining the K-702 polyimide diaphragm compression driver on a Tractrix Mumps midrange horn, a K-100-TI 1-inch titanium compression tweeter with wide-dispersion phase plug, and a K-281 12-inch fiber-composite woofer paired with a rear-mounted KD-15 15-inch passive radiator. With 99 dB sensitivity and a 38Hz to 20kHz frequency response from a cabinet measuring just 35.75 inches tall and 13 inches deep, the Forte IV delivers Heritage Series performance in a footprint accessible to rooms that cannot accommodate the Cornwall IV or La Scala. Handcrafted to order in Hope, Arkansas, and backed by a 10-year warranty, the Forte IV is sold individually in American Walnut, Natural Cherry, Black Ash, and Distressed Oak finishes.

K-702 Tractrix Mumps Midrange Horn and Wide-Dispersion Phase Plug Tweeter

The acoustic centerpiece of the Forte IV is the K-702 polyimide diaphragm compression driver, the same midrange unit introduced in the Cornwall IV, mounted to the K-703-M Tractrix horn with Mumps technology. The K-702 replaces the smaller compression driver used in the Forte III with a larger-diaphragm unit that generates greater sound pressure at the horn throat and delivers more dynamic authority and low-distortion performance through the critical 650Hz to 5.2kHz midrange passband. The Tractrix horn geometry minimizes internal reflections and produces a controlled, even dispersion pattern across the listening room, while Mumps technology corrects the diffraction anomalies at the horn's edges that cause off-axis frequency response irregularities in conventional horn designs. The result is a midrange presentation that is more consistent at wider listening angles than the Forte III, with a larger and more stable sweet spot for off-center listening positions. At the top of the frequency range, the K-100-TI 1-inch titanium diaphragm compression driver on the K-79T horn receives an all-new wide-dispersion phase plug that equalizes the acoustic path length across the diaphragm surface, reducing high-frequency phase cancellations and extending the tweeter's even coverage to wider horizontal angles, matching the dispersion pattern established by the Tractrix Mumps midrange horn for a more seamless, cohesive top-to-bottom presentation.

15-Inch Passive Radiator and Klipschorn-Influenced Crossover Network

The Forte IV's bass system pairs a front-firing K-281 12-inch fiber-composite woofer with a rear-mounted KD-15 15-inch passive cone radiator, a design approach that achieves the low-frequency output and extension of a much larger enclosure from the Forte IV's relatively compact 13-inch-deep cabinet. The passive radiator operates on the acoustic pressure generated by the active woofer inside the sealed portion of the enclosure, moving in response to this pressure to produce additional low-frequency output below the woofer's natural resonance frequency. The 15-inch passive radiator surface area gives it the radiating capability to produce deep, clean bass extension to 38Hz in a cabinet that would produce significantly less bass output as a conventional sealed or ported design at the same dimensions. The crossover network, referred to by Klipsch as a network rather than a crossover in alignment with Paul W. Klipsch's original terminology, draws its steep-slope design from the Klipschorn and La Scala rather than conventional loudspeaker crossover practice. Roy Delgado, Klipsch's principal acoustician and Paul W. Klipsch protégé, redesigned the network from scratch for the Forte IV using premium components that reduce electrical degradation in the signal path, and the wiring throughout the network and to each driver is a higher-performance grade than used in the Forte III.

Key Features

• K-702 Polyimide Compression Driver with Tractrix Mumps Horn: The same midrange driver used in the Cornwall IV, delivering greater sound pressure at the horn throat, improved dynamics, and more even polar response across wider listening angles compared to the Forte III's midrange configuration.
• K-100-TI Titanium Tweeter with Wide-Dispersion Phase Plug: A 1-inch titanium diaphragm compression driver with a new wide-dispersion phase plug provides exceptionally even high-frequency coverage, matching the dispersion pattern of the Tractrix Mumps midrange horn for a coherent, integrated soundstage.
• K-281 12" Woofer with KD-15 15" Passive Radiator: A front-firing 12-inch fiber-composite woofer paired with a rear-mounted 15-inch passive radiator achieves bass extension to 38Hz and dynamic low-frequency output from a cabinet just 13 inches deep.
• Klipschorn-Influenced Steep-Slope Network: A completely redesigned crossover network using premium components and steep-slope filter design derived from the Klipschorn and La Scala, minimizing electrical degradation and driver interference across the crossover regions at 650Hz and 5.2kHz.
• 99 dB Sensitivity: Near-triple-digit sensitivity enables concert-level listening from amplifiers rated at as little as 1 watt per channel, including single-ended triode tube designs, while remaining fully compatible with high-power solid-state amplifiers.
• Compact Heritage Footprint: At 35.75 inches tall, 16.63 inches wide, and 13 inches deep, the Forte IV delivers Heritage Series horn performance in a cabinet significantly smaller than the Cornwall IV, La Scala, or Klipschorn.
• Brushed Aluminum Bi-Wire / Bi-Amp Input Panel: A premium aluminum rear input panel with dual 5-way binding posts accepts large-diameter speaker cables and supports bi-wiring and bi-amplification configurations.
• Book-Matched Real Wood Veneer with Grain-Matched Pairs: Each cabinet is finished with book-matched veneer from the same timber, and every matched pair shares sequentially selected veneer panels from the same timber source, confirmed by sequential serial numbers.
• Handcrafted in Hope, Arkansas: Every Forte IV enclosure is assembled to order by Klipsch craftsmen in Hope, Arkansas using highest-grade adhesives and fasteners, continuing the manufacturing tradition established by Paul W. Klipsch in 1946.
• 10-Year Warranty: The full Klipsch Heritage Series, including the Forte IV, carries a 10-year warranty covering defective materials and workmanship.

Technical Specifications

Awards and Critical Recognition

• Stereophile: Full review by Art Dudley, praising the Forte IV's refinement, richer midrange, and wider soundstage over the Forte III (2021)
• StereoNET Applause Award, Floorstanding Loudspeakers category (2021)
• Hi-Fi+: Recommended product, cited for natural tonal balance and improved dispersion over earlier Heritage models (2023)

Frequently Asked Questions

What is the Klipsch Forte IV?

The Klipsch Forte IV is a three-way horn-loaded floorstanding loudspeaker from Klipsch (Hope, Arkansas, USA), and the fourth generation of a Heritage Series design originally introduced in 1985. It features the K-702 polyimide compression driver on a Tractrix Mumps midrange horn, a K-100-TI titanium tweeter with wide-dispersion phase plug, a K-281 12-inch fiber-composite woofer, and a rear-mounted KD-15 15-inch passive radiator. It delivers 99 dB sensitivity, a 38Hz to 20kHz frequency response, and 116 dB maximum SPL from a compact cabinet 35.75 inches tall and 13 inches deep. It is sold as a single speaker in American Walnut, Natural Cherry, Black Ash, and Distressed Oak finishes.

How does the Klipsch Forte IV compare to the Klipsch Cornwall IV or Focal Kanta No.3?

The Klipsch Forte IV sits one step below the Cornwall IV in the Heritage Series hierarchy. The Cornwall IV uses the same K-702 midrange compression driver and Tractrix Mumps horn, but adds a larger 15-inch direct-radiating woofer, three front-firing Tractrix ports, a taller and wider cabinet, and 102 dB sensitivity versus the Forte IV's 99 dB, placing it above the Forte IV in bass output and overall dynamic authority. The Forte IV's passive radiator bass system is a meaningful acoustic achievement for its cabinet size but does not match the Cornwall IV's bass extension or efficiency. Compared to the Focal Kanta No.3, which is a conventional dynamic speaker at approximately 91 dB sensitivity and 4 ohms nominal impedance, the Forte IV delivers substantially greater dynamic headroom per watt and is a fundamentally better match for low-power tube amplification, while the Kanta No.3 prioritizes imaging precision and low-level resolution in smaller listening environments.

What does the 15-inch passive radiator do for bass performance?

The KD-15 15-inch passive radiator on the rear of the Forte IV is a large-diameter cone without a voice coil or magnet that moves in response to the acoustic pressure generated by the active K-281 12-inch woofer inside the sealed enclosure. By coupling the energy of the active woofer to this large radiating surface, the passive radiator produces additional low-frequency output below the frequency where the active woofer's output alone would roll off, extending bass response to 38Hz from a cabinet just 13 inches deep. The 15-inch radiating surface is substantially larger than the bass reflex ports used in comparable enclosures of similar volume, allowing the passive radiator to move significant air volume at low frequencies with less excursion and lower distortion per unit of bass output than a port-based design of equivalent cabinet size.

Can the Klipsch Forte IV be driven by a low-power tube amplifier?

Yes, the Forte IV is one of the most tube-amplifier-compatible speakers at its price and performance level. At 99 dB sensitivity and 8 ohms nominal impedance, it produces substantial output from amplifiers rated at as few as 2 to 8 watts per channel, including single-ended triode designs using 300B, 2A3, or EL34 output tubes. Reviewers at Stereophile and The Ear have successfully driven the Forte IV with sub-10-watt tube amplifiers and reported excellent results in dynamics and tonal richness. The consistent 8-ohm impedance across the frequency range simplifies amplifier matching and avoids the reactive impedance dips that challenge output-transformer-coupled tube amplifiers. Klipsch also confirms the Forte IV works equally well with high-power solid-state amplifiers, which reviewers note can improve bass control and dynamic composure at higher volume levels.

How does the Forte IV differ from the Forte III?

The Klipsch Forte IV introduces meaningful acoustic upgrades over the Forte III at every driver and crossover level. The midrange compression driver has been upgraded from the Forte III's smaller unit to the K-702 polyimide driver, the same component used in the Cornwall IV, paired with a new Tractrix Mumps horn replacing the Forte III's conventional horn profile. The tweeter received a new wide-dispersion phase plug for more even high-frequency coverage. The crossover network was completely redesigned with steeper slopes, premium components, and higher-performance internal wiring, drawing its design philosophy from the Klipschorn and La Scala networks rather than the Forte III's crossover. Stereophile's Art Dudley, who reviewed both models, described the IV as noticeably smoother, richer, and more refined through the midrange and upper treble, with a deeper soundstage and wider presentation than the Forte III in direct comparison.

Where can I buy the Klipsch Forte IV in Toronto or Canada?

The Klipsch Forte IV floorstanding speaker is available at Vinyl Sound in Toronto, Canada. Vinyl Sound is an authorized Klipsch Heritage dealer carrying the Forte IV alongside the full Klipsch Heritage Series lineup including the Cornwall IV, Klipschorn AK7, and Jubilee. The Forte IV is built to order in Hope, Arkansas, and buyers in Toronto and across Canada are welcome to contact Vinyl Sound to discuss finish options, lead times, and system pairing recommendations before placing an order.

What room size suits the Klipsch Forte IV?

The Klipsch Forte IV is well suited to a wide range of room sizes, from medium domestic listening rooms of approximately 200 to 400 square feet up to larger open-plan spaces where its 99 dB sensitivity allows it to fill the room with minimal amplifier power. Its compact 13-inch depth makes it practical in rooms where the Cornwall IV or La Scala's larger footprint would be challenging. The Forte IV benefits from placement away from the rear wall to allow the 15-inch passive radiator to breathe and develop its full bass character, and Klipsch recommends experimenting with toe-in angle to optimize imaging focus and soundstage width at the primary listening position.