Klipsch Heresy IV Speaker (Each) at Vinyl Sound Toronto Canada

The Heresy IV is a three-way horn-loaded loudspeaker from Klipsch (Hope, Arkansas, USA), available at Vinyl Sound in Toronto, Canada. Originally introduced in 1957 as a compact center channel speaker to accompany Klipschorns in three-speaker stereo arrays, the Heresy IV is the fourth generation of this Heritage Series icon and the most compact Heritage model currently in production. The Heresy IV features the K-702 1.75-inch polyimide diaphragm compression driver on the K-704 Tractrix horn, the K-107-TI 1-inch titanium tweeter with wide-dispersion phase plug, and the K-28-E 12-inch fiber-composite woofer now vented for the first time in the model's history through a rear-mounted Tractrix port with AudioQuest Type 4 Star-Quad internal wiring throughout. At 99 dB sensitivity, 48Hz to 20kHz frequency response, and 116 dB maximum SPL from a cabinet just 24.81 inches tall and 13.25 inches deep, the Heresy IV is the entry point to Heritage Series horn performance. Sold individually in Satin Black Ash, Natural Cherry, Distressed Oak, and American Walnut finishes, and handcrafted in Hope, Arkansas with a 10-year warranty.

K-702 Tractrix Midrange Horn and First-Generation Rear Tractrix Port

The acoustic transformation from Heresy III to Heresy IV centers on two complementary upgrades: the introduction of the K-702 polyimide diaphragm compression driver and the addition of the Heresy's first-ever bass reflex port. The K-702, shared with the Cornwall IV and Forte IV, replaces the Heresy III's smaller titanium compression driver with a 1.75-inch polyimide unit that produces greater sound pressure at the K-704 Tractrix horn throat and delivers more dynamic midrange energy through the critical 850Hz to 4.5kHz passband that carries vocals, acoustic instruments, and upper harmonics. The K-704 Tractrix horn geometry controls the rate of wavefront expansion from throat to mouth, minimizing internal reflections and producing a smooth, wide coverage pattern that extends consistent midrange response to wider horizontal listening angles. The crossover point between the midrange and tweeter has been lowered by 500Hz compared to the Heresy III, allowing the K-702 to handle more of the frequency range it is optimized for and reducing the burden on the tweeter at frequencies where its distortion characteristics are less favorable. For the first time in the Heresy's 65-plus year history, the Heresy IV adds a rear-mounted Tractrix port, extending low-frequency performance approximately 10Hz deeper than the Heresy III's sealed enclosure and producing punchier, faster bass transients with lower port noise than conventional rectangular port geometries.

AudioQuest Type 4 Star-Quad Internal Wiring and Klipschorn-Influenced Network

The Heresy IV's crossover network, redesigned entirely for the IV generation, draws its steep-slope design philosophy from the Klipschorn and La Scala, applying the same approach Klipsch's principal acoustician Roy Delgado used for the Cornwall IV and Forte IV to the most compact speaker in the Heritage Series. The crossover frequency points at 850Hz and 4.5kHz are carried by premium components chosen to minimize electrical degradation through the signal path. The internal wiring connecting the binding posts, crossover network, and each driver is AudioQuest Type 4 with Star-Quad Geometry, a high-quality conductor arrangement using solid long-grain copper conductors in a four-group star pattern with carbon-loaded insulation and nitrogen-injected polyethylene dielectric. This level of internal wiring specification is rarely encountered in speakers at any price point and reflects the overall elevation in componentry that distinguishes the Heresy IV from its predecessor and from comparable-footprint competitors.

Key Features

• K-702 1.75" Polyimide Compression Driver on K-704 Tractrix Horn: The same midrange driver used in the Cornwall IV and Forte IV, delivering greater sound pressure, wider dispersion, and more dynamic midrange performance than the Heresy III's driver, with a 500Hz lower crossover handoff to the tweeter for improved integration.
• K-107-TI Titanium Tweeter with Wide-Dispersion Phase Plug: A 1-inch titanium diaphragm compression driver with a new wide-dispersion phase plug provides even, consistent high-frequency coverage across a wider horizontal angle, expanding the effective listening sweet spot.
• K-28-E 12" Fiber-Composite Woofer: A 12-inch fiber-composite woofer provides the low-frequency foundation, now supported by a rear-mounted Tractrix port for the first time in the Heresy's history, extending bass response to 48Hz with tighter, lower-distortion transients.
• First-Ever Rear Tractrix Port: The Heresy IV adds a rear-mounted Tractrix-geometry bass reflex port with custom inner flares that reduce air turbulence, extending low-frequency performance approximately 10Hz deeper than the sealed Heresy III with lower port noise and punchier bass output.
• AudioQuest Type 4 Star-Quad Internal Wiring: All internal signal wiring uses AudioQuest Type 4 with Star-Quad Geometry and solid long-grain copper conductors, minimizing electrical degradation from input panel to drivers throughout the entire signal path.
• Klipschorn-Influenced Steep-Slope Network: A completely redesigned crossover network with crossover points at 850Hz and 4.5kHz, using premium components and steep-slope design derived from the Klipschorn and La Scala for cleaner driver transitions and reduced interference between passbands.
• 99 dB Sensitivity: One of the highest sensitivity ratings of any compact three-way loudspeaker commercially produced, enabling full-volume listening from single-digit watt tube amplifiers including single-ended triode designs.
• Compact Heritage Footprint: At 24.81 inches tall, 15.5 inches wide, and 13.25 inches deep, the Heresy IV is the most compact and placement-flexible speaker in the Klipsch Heritage Series, accessible to rooms that cannot accommodate the Forte IV, Cornwall IV, or Klipschorn AK7.
• Tilted Riser Base: The Heresy IV includes an integrated riser base that angles the speaker slightly upward toward ear level at a typical seated listening distance, optimizing the driver axis without requiring dedicated stands. The riser can be removed for in-cabinet or custom stand installation.
• Book-Matched Real Wood Veneer with Sequential Serial Numbers: Each matched pair uses book-matched veneer from the same timber, with sequential serial numbers confirming factory-matched acoustic and visual pairing.
• Handcrafted in Hope, Arkansas: Every Heresy IV enclosure is assembled to order by Klipsch craftsmen in Hope, Arkansas using highest-grade adhesives and fasteners, carrying the 10-year Heritage Series warranty.

Technical Specifications

Awards and Critical Recognition

• What Hi-Fi?: "The Heresy IV is still manufactured in the good ol' USA, in Hope, Arkansas. The only thing that has really changed is the sound... and that change has been for the better." (2021)
• StereoNET Applause Award, Floorstanding Loudspeakers category (2021)

Frequently Asked Questions

What is the Klipsch Heresy IV?

The Klipsch Heresy IV is a three-way horn-loaded loudspeaker from Klipsch (Hope, Arkansas, USA), first introduced in 1957 and now in its fourth generation. It features the K-702 1.75-inch polyimide compression driver on the K-704 Tractrix horn, the K-107-TI 1-inch titanium tweeter with wide-dispersion phase plug, and the K-28-E 12-inch fiber-composite woofer in a vented enclosure with a rear Tractrix port. It delivers 99 dB sensitivity, 48Hz to 20kHz frequency response, and 116 dB maximum SPL from a cabinet just 24.81 inches tall, making it the most compact speaker in the Klipsch Heritage Series. Internal wiring uses AudioQuest Type 4 Star-Quad cable throughout.

How does the Klipsch Heresy IV compare to the Klipsch Forte IV or the KEF R7?

The Klipsch Heresy IV sits below the Forte IV in the Heritage Series hierarchy. The Forte IV uses the same K-702 midrange driver and Tractrix Mumps horn, but adds a larger 12-inch K-281 woofer, a rear-mounted 15-inch passive radiator for deeper bass extension to 38Hz versus the Heresy IV's 48Hz, and a taller cabinet with greater cabinet volume for more dynamic low-frequency authority. The Forte IV's Mumps horn technology is also absent from the Heresy IV's K-704 horn. Compared to the KEF R7, which is a conventional dynamic speaker at approximately 88 dB sensitivity and 8 ohm nominal impedance, the Heresy IV's 99 dB sensitivity represents a fundamental architectural advantage for low-power tube amplification, enabling single-watt amplifiers to produce concert-level output where the R7 would require 100 times more power for equivalent SPL. The R7 offers different strengths in low-level resolution and deep bass extension in a slimmer floorstanding format.

What is new in the Heresy IV compared to the Heresy III?

The Heresy IV introduces comprehensive upgrades at every level over the Heresy III. The midrange compression driver has been upgraded to the K-702 polyimide unit, shared with the Cornwall IV and Forte IV, replacing the Heresy III's smaller titanium driver. The K-704 Tractrix horn replaces the previous midrange horn for smoother dispersion. The tweeter receives a new wide-dispersion phase plug for improved high-frequency coverage and a 500Hz lower crossover handoff point from the midrange. Most significantly, the Heresy IV adds a rear-mounted Tractrix port for the first time in the model's history, extending bass approximately 10Hz deeper than the sealed Heresy III. The crossover network has been completely redesigned with premium components modelled on the Klipschorn and La Scala, and AudioQuest Type 4 Star-Quad internal wiring replaces the previous generic wiring throughout.

Does the Heresy IV need a subwoofer?

The Klipsch Heresy IV is rated to 48Hz at the -4 dB point, which covers the fundamental frequencies of most acoustic instruments including double bass (lowest note approximately 41Hz) and bass guitar. Many listeners use the Heresy IV without a subwoofer in medium-sized rooms and find its bass output satisfying for music listening. However, audiophiles who prioritize deep bass extension below 40Hz for pipe organ, synthesizer bass, or home theater low-frequency effects will benefit from pairing the Heresy IV with a quality subwoofer. The Heresy IV's relatively high bass rolloff frequency, compared to the Forte IV and Cornwall IV, actually simplifies subwoofer integration by allowing a clean acoustic handoff to the subwoofer with minimal overlap between the two systems.

Can the Heresy IV be used with a flea-watt tube amplifier?

Yes, the Heresy IV is one of the most compatible commercially available speakers for low-power single-ended triode amplification. At 99 dB sensitivity and 8 ohms nominal impedance, even a 1 to 3-watt single-ended triode amplifier using 2A3 or 300B output tubes produces room-filling output with the Heresy IV. The consistent 8-ohm impedance simplifies output transformer matching for tube amplifier designs. Reviewers at 7Review and Steve Huff HiFi have verified the Heresy IV's exceptional compatibility with sub-10-watt tube amplifiers, reporting excellent dynamics, tonal richness, and midrange presence even at very low power levels. Klipsch itself confirms the Heresy IV works equally well with high-power solid-state amplifiers for listeners who prefer that combination.

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

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

Is the Heresy IV suitable as a center channel speaker?

Yes, the Heresy IV is historically a center channel speaker at its core, having been designed in 1957 specifically to serve as the center fill channel between two widely spaced Klipschorns. Its compact dimensions of 24.81 x 15.5 x 13.25 inches and removable riser base make it practical for horizontal placement in a home theater cabinet below a display. In a modern home theater context, the Heresy IV performs excellently as a center channel matched with larger Klipsch Heritage speakers as front left and right, delivering the same horn-loaded midrange character and 99 dB sensitivity across all three front channels for seamless dialogue and soundstage integration.