In-Wall (2×4) RTL Subwoofer with Port Extension Kit

The S55-f/c can be mounted in-ceiling, in-wall, under risers, in closets, and on floors. It is a rare example of a custom-centric design that offers competitive results versus the finest freestanding options. The S55-f/c is a strong performer, featuring the quickness and tonality all our RTL subwoofers are known for, with bass extension to 40Hz. Its size makes it well suited to being custom-installed and thereby hidden behind its small paintable grill and bezel.

The Regenerative Transmission Line®

Regenerative Transmission Line® designs yielded the unique combination of high sensitivity, high output, and low distortion with the uniform and extended response we required. The result is extraordinary power and punch combined with a remarkable level of quickness, tunefulness, and realism.

Key Features

In-wall (2×4) with Grille
Regenerative Transmission Line® Design

Highly Detailed & Dynamically Accurate
(4) Custom Designed High-Output Long throw 3”x5” Woofers

Optional floor/ceiling extension port kit available for venting into space from an adjacent room, attic, riser, ceiling, and/or floor.

Flat Frequency Response Across a 40Hz-80Hz Operating Range
(4) High Operating Woofers
DSP Required
(1) Channel of Power Amplification per Subwoofer Required


Frequency Response40Hz – 80 Hz ± 3dB relative to the target curve
Impedance8 ohms
Sensitivity90 dB / 2.83 V / 1m
Power Handling, Peak240w
Maximum SPL112dB / 40Hz / 1m
Shipping Weight43 lbs. (20 kg
Dimensions – HxWxD54” x 15.875” x 4.25” (137.1cm x 35.9cm x 10.5cm)


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S55i Owner’s Manual

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S55i Dimensions (PDF)

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S55i Dimensions (DWG)

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Port Extension Kit (PDF)

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Port Kit Installation Manual

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