In-Wall (2×4) Regenerative Transmission Line® RTL Subwoofer

The S55i can be mounted in-ceiling, in-wall, under risers, in closets, and in floors. It is a rare example of a custom-centric design that offers competitive results versus the finest freestanding options. The S55i 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.

Key Features


In-wall (2×4) with grille

Regenerative Transmission Line® design

Key Benefits

Highly Detailed

(4) Custom designed high-output long throw 3”x5” woofers


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


More Features

Flat frequency response across a 40Hz-80Hz operating range

(4) High operating Woofer

(DSP Required)

(1) Channel of Power Amplification

Per subwoofer required

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.


Frequency response 40Hz – 80 Hz ± 3dB relative to the target curve
Impedance 8 ohms
Sensitivity 90 dB / 2.83V / 1m
Power handling, peak 240w
Maximum SPL 112dB / 40Hz / 1m
Shipping weight 43 lbs. (20 kg)
Dimensions HxWxD 54” x 15.875” x 4.25” (137.1cm x 35.9cm x 10.5cm)