Klipsch Forte IV Red Oak (pack of 2)

The Klipsch [Forte IV is]() a three-way loudspeaker positioned between the Heresy IV and the Cornwall IV. This fourth-generation model in a series launched in 1985 blends traditional design with contemporary acoustic enhancements while preserving the sonic character of the Heritage line.

Handcrafted construction that stands the test of time

The Forte IV speaker continues a manufacturing tradition dating back to 1946, when Paul Wilbur Klipsch founded his company in a modest shed in Hope, Arkansas. Each unit is still assembled by hand in the same town by craftsmen, some of whom have been honing this expertise for decades. The 19 mm MDF cabinet is finished with real wood veneer using the book-matching technique: veneer leaves are kept in their cutting order and laid out in mirror symmetry to create striking visual continuity.

The Auburn finish (American mahogany) stands out with warm hues ranging from deep brown to copper highlights, especially when natural light reveals the wood grain. This shade is noticeably darker than American walnut yet warmer than black ash. The Salt and Pepper grille cloth, a subtle weave of gray and white threads, brings a discreet touch of modernity to this neo-vintage aesthetic.

Each pair is meticulously matched (grain-matching) using veneer panels from the same tree. The two speakers travel together through the factory and receive consecutive serial numbers, ensuring perfect visual and acoustic consistency. This artisanal approach partly explains the substantial weight of 32.7 kg per speaker and their imposing dimensions of 90.81 cm in height, 42.24 cm in width, and 33 cm in depth.

A subtly rethought acoustic architecture

The Forte IV’s three-way configuration conceals significant innovations behind a familiar appearance. The new 44.5 mm K-702 compression driver with a polyimide diaphragm replaces the previous model and is the most substantial change in this generation. Mounted on a Tractrix K-703-M horn integrating Klipsch’s patented Mumps technology, this midrange delivers more uniform polar dispersion, considerably widening the optimal listening area.

The K-100-TI compression tweeter retains its 25.4 mm titanium diaphragm but now benefits from a wide-dispersion ABS phase plug. This seemingly minor tweak transforms high-frequency reproduction by offering horizontal dispersion roughly 20 degrees wider than on the Heresy IV in the critical 500 Hz–1 kHz band. The K-79T horn that houses it maintains its 15 cm × 10 cm dimensions, optimized for controlled directivity without harshness.

Bass is handled by a 30.5 cm K-281 woofer with a fiber-composite diaphragm, supported by a rear passive radiator, the 38 cm KD-15. This hybrid configuration, introduced in 1985 on the original Forte by engineer Gary Gillum, achieves bass extension down to 38 Hz without requiring an oversized cabinet. Unlike a traditional port, the passive radiator operates via acoustic pressure generated by the active woofer, offering superior low-frequency control and avoiding unwanted port chuffing.

A sophisticated crossover that changes the game

The crossover network is the most profound transformation in this fourth generation, even though the crossover points remain at 650 Hz and 5.2 kHz. Roy Delgado, Klipsch’s chief acoustics engineer for four decades, completely reworked the topology, drawing inspiration from the steep slopes used in the legendary Klipschorn and La Scala. This approach minimizes overlap between drivers, thereby reducing interference and distortion.

The new circuit uses premium components and asymmetric attenuation slopes: the high-pass filters employ genuinely steep slopes in line with Paul W. Klipsch’s philosophy, while the woofer and midrange low-pass filters retain gentler slopes. This hybrid architecture, the fruit of meticulous optimization, helps explain why the Forte IV sounds more refined and coherent than its predecessor.

The solid aluminum input binding posts accept thick-gauge cables and allow for bi-wiring or bi-amping. The robust, versatile terminals reflect a design built to last generations. This construction quality is evident throughout the product, from the structural adhesives used in assembly to the oversized mechanical fasteners.

Acoustic performance balancing power and finesse

With a sensitivity of 99 dB for 2.83 V at 1 meter, the Forte IV sits in the rare category of very high-efficiency speakers. This exceptional efficiency delivers a continuous 116 dB with just 100 watts, while maintaining perfect compatibility with low-power amplifiers. A 2.5-watt single-ended triode tube amplifier can theoretically produce comfortable listening levels in a medium-sized room.

Frequency response extends from 38 Hz to 20 kHz (±3 dB), with a notable characteristic in the 2–4 kHz range, which is slightly more restrained than typical Klipsch standards. This less aggressive upper midrange paradoxically enables more comfortable long listening sessions, even if some purists miss a touch of vocal presence. The nominal 8-ohm impedance hides a measured minimum of 3.1 ohms, requiring an amplifier stable into complex loads.

The soundstage unfolds with remarkable breadth, extending well beyond the speakers’ physical boundaries. This generous spatialization is accompanied by greater depth compared to the Forte III, creating a three-dimensional sonic bubble that is particularly convincing on live recordings. Dynamics, a historic Klipsch strength, preserve micro-contrast even at low volume, making late-night listening especially rewarding.

Placement and acoustic optimization

Contrary to common belief, the Forte IV tolerates relatively close placement to the rear wall. Klipsch recommends a spacing of 5 to 25 cm, with the rear passive radiator requiring at least 2.5 cm to function properly. In practice, positioning about 90 cm from the rear wall often yields the best tonal balance, avoiding midrange masking without sacrificing low-frequency extension.

Optimal spacing between the two speakers ranges from 1.8 to 4.5 meters depending on room size, with a direct toe-in toward the listening position recommended to maximize stereo image coherence. This pronounced orientation compensates for the horns’ inherent directivity and broadens the sweet spot, particularly beneficial when multiple listeners share the space.

Medium-sized rooms (15 to 25 m²) are ideal, unlike the higher Heritage models, which demand more generous volumes. Acoustic treatment remains secondary thanks to the horns’ controlled directivity that minimizes parasitic reflections. A simple rug between the speakers and the listening position is generally sufficient to optimize reproduction.

Technical Specifications

Acoustic Configuration

• 3-way horn-loaded loudspeaker, 30 cm woofer
• K-702 polyimide midrange on Tractrix Mumps horn
• K-100-TI titanium tweeter with phase plug, wide sweet spot
• 38 cm passive radiator for deep bass

Acoustic Performance

• Frequency response: 38 Hz – 20 kHz (±3 dB)
• High sensitivity: 99 dB @ 2.83 V / 1 m for optimal efficiency with low power
• Power handling: 100 W continuous / 400 W peak
• Maximum sound pressure level: 116 dB continuous
• Nominal impedance: 8 ohms

Drivers and Transducers

• K-281 woofer: 30 cm composite cone
• KD-15 passive radiator: 38 cm
• K-702 midrange: 44 mm compression driver with polyimide diaphragm
• K-100-TI tweeter: 25 mm compression driver with titanium diaphragm
• Crossover frequencies: mids 650 Hz / highs 5.2 kHz

Connectivity and Amplification

• Dual binding posts for bi-wiring / bi-amping
• Maximum flexibility in amplification setup

Construction and Dimensions

• 19 mm medium-density fiberboard (MDF) enclosure
• Dimensions (H × W × D): 90.81 × 42.24 × 33 cm
• Weight: 32.7 kg
• Rugged design assembled with premium adhesives and fasteners

Available Finishes

• Black Ash (black ash)
• American Walnut (American walnut)
• American Auburn
• Red Oak (red oak)

Manufacturing and Design

• Handcrafted in the US, book-matched wood veneers
• Matched pairs for visual consistency
• Built to last for generations