Midrange Horns.

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The Fastrac 401 is back with an updated design for the Klipsch La Scala and Klipschorn. Created as a direct-fit replacement for the factory K-400 midrange horn, it works with the original K-55-style 1-inch compression driver and fits the existing horn location.

Its tractrix-based flare provides smooth, spacious midrange reproduction while preserving the sensitivity and dynamic character that make these classic loudspeakers so engaging.

Flare cutoff (Fc): 317 Hz
Throat size: 1 inch
Driver compatibility: K-55-style compression drivers
Loudspeaker compatibility: Klipsch La Scala and Klipschorn
Installation: Direct-fit K-400 replacement
Sold as a matched pair

The Fastrac 402 is a direct-fit replacement for the factory K-400 midrange horn used in the Klipsch La Scala and Klipschorn. Designed with a 2-inch throat, it allows these classic loudspeakers to accommodate modern large-format compression drivers while retaining the original horn location.

Its tractrix-based profile provides smooth, open midrange reproduction with excellent clarity and spaciousness. A mounting adapter is available for customers who prefer to use the original K-55-style 1-inch driver.

Flare cutoff (Fc): 317 Hz
Throat size: 2 inches
Compatibility: Klipsch La Scala and Klipschorn
Installation: Direct-fit K-400 replacement
Optional K-55 1-inch adapter: $50
Sold as a matched pair

Designed as direct-fit replacements for the factory K-500 midrange horn used in the Klipsch Belle, the Fastrac 501 and 502 provide a smooth, open midrange presentation while retaining the original cabinet opening and mounting location.

The Fastrac 501 is designed for the original K-55-style 1-inch compression driver. The Fastrac 502 provides the same cabinet compatibility with a 2-inch throat for builders using a large-format 2-inch driver.

Fastrac 501: 1-inch throat for K-55-style drivers
Fastrac 502: 2-inch throat for large-format drivers
Compatibility: Klipsch Belle
Installation: Direct-fit K-500 replacement
Sold as a matched pair

Eliptrac 400 — $600 per pair plus shipping

The FastLane Audio Eliptrac 400 is a large-format midrange horn designed for custom three-way loudspeaker systems. Its 300 Hz flare cutoff provides the low-frequency capability needed for demanding midrange applications while delivering the smooth, open presentation associated with the Eliptrac profile.

An excellent choice for Cornscala-style projects, the Eliptrac 400 can also be incorporated into Klipschorn and Belle installations using custom grilles. A full-size cutting template is included to simplify cabinet layout and installation.

Flare cutoff (Fc): 300 Hz
Application: Midrange use in three-way systems
Recommended for: Cornscala and custom loudspeaker projects
Installation: Cutting template included
Sold as a matched pair

The Fastrac 601 is a direct-fit midrange horn upgrade for the original Klipsch Cornwall. Designed to work with the factory cabinet opening, midrange driver, and crossover network, it provides a straightforward upgrade without requiring a complete loudspeaker redesign.

Its smooth tractrix profile delivers a more open, natural midrange presentation with improved clarity and spaciousness. The factory-style mounting flange makes installation clean and uncomplicated.

Application: Three-way midrange horn
Compatibility: Original Klipsch Cornwall
Installation: Direct-fit replacement
Sold as a matched pair.

The Fastrac 701 is a modern replacement for the original Klipsch K-700 midrange horns. Its compact hybrid tractrix profile was developed to provide smooth, open midrange reproduction while fitting within the limited space available in the original cabinet.

The carefully shaped flare maintains the low-frequency loading required for proper midrange operation without sacrificing the natural, spacious sound associated with a tractrix horn.

Designed for straightforward installation in compatible Klipsch loudspeakers and sold as a matched pair.

The FastLane Audio FT-601-II is a direct drop-in replacement for the factory K-601 midrange horn used in the Klipsch Cornwall II and original Chorus (Chorus I).

Designed for three-way loudspeaker operation, the FT-601-II has an approximate 500 Hz flare cutoff and is recommended for crossover frequencies of 600 Hz or higher. Its smooth horn profile provides clean, open midrange reproduction while retaining compatibility with the original cabinet opening and crossover configuration.

Includes adapters for K-52-style midrange drivers.

Compatible with:

• Klipsch Cornwall II
• Klipsch Chorus I
• Loudspeakers using the factory K-601 horn

Approximate flare cutoff: 500 Hz
Recommended minimum crossover: 600 Hz
Application: Three-way midrange horn
Sold as a matched pair

FT-601-II and original K-601 comparison

Side-by-side view of the FastLane Audio FT-601-II (left) and the original Klipsch K-601 horn (right), showing their comparable overall size, mounting footprint, and drop-in compatibility.

The FastLane Audio Eliptrac 240 is a dedicated midrange horn for custom three-way loudspeaker systems. With a 240 Hz flare cutoff (Fc), a crossover frequency of 350 Hz or higher is recommended to provide a comfortable operating margin.

The Eliptrac 240 is an excellent choice for Cornscala-style builds and can also be adapted for use in Klipschorn and Belle installations with custom grilles. A cutting template is included to simplify installation.

Flare cutoff (Fc): 240 Hz
Recommended crossover: 350 Hz or higher
Application: Midrange use in three-way systems
Sold as a matched pair.

Installing the FT-701-II

The FT-701 requires only a minor adjustment to the factory horn opening. Using a Dremel or similar rotary tool, remove approximately 1/16 inch of material from the top and bottom of the cabinet opening.

The cabinet provides plenty of material for this small adjustment, allowing the horn itself to remain completely unmodified. Once fitted, the FT-701 mounts securely for a clean, factory-style installation.

A Modern Replacement for the klipsch K-700

The original Klipsch K-700 and K-701-II are compact, well-proven midrange horns. Their limited mouth area, however, makes it difficult to fit a conventional tractrix profile into the original cabinet opening.

The FT-701-II solves this challenge with a carefully developed hybrid tractrix flare. It delivers the required low-frequency loading while preserving the smooth, open midrange character associated with a tractrix design—all in a horn sized for the original installation.

The FT-701 is an excellent upgrade for the Klipsch Heresy II, Heresy III, Super Heresy II, and Forte I.

The Forte II already uses Klipsch’s larger tractrix midrange horn and does not require this upgrade.

The FastLane Audio Catalyst is a top-mount horn designed for high-output two-way and three-way loudspeaker systems. With an approximate 325 Hz flare cutoff (Fc), it is intended for operation with a recommended crossover point of 500 Hz or higher. Its compact design makes it a practical choice for builders who want strong midrange performance without mounting the horn inside the enclosure.

Recommended crossover: 500 Hz
Approximate flare cutoff (Fc): 325 Hz
Suitable for: Two-way and three-way systems
Mounting: Top mount