IWTS-28 SUB/SA-180 Monoblock Amplifier

In-Wall Subwoofer, perfect for retro-fit!

sm_IWTS-28_SUB_front.jpg“This is the in-wall sub I've wanted from Atlantic for a long time!” — Bruce Eckert, BWE Electronics

Powerful in-wall bass that hides from view
The IWTS-28 SUB is an in-wall subwoofer that uses dual heavy-duty 8" woofers to deliver rich, vibrant bass to custom-installed audio systems. It is easily retro-fitted to existing construction using Atlantic's GFR-626 grille/frame assembly, the same grille/frame assembly used for the IWTS-30 LCR THX Ultra 2.

Boasting amazing hookup flexibility, the 28 SUB can either be used passively, driven directly off the receiver's front Left/Right speaker outputs by utilizing the 28 SUB's on-board low-pass crossover, OR it can be driven actively by using a power amplifier such as our SA-180 connected to the receiver's 'sub out' jack. The 28 SUB's on-board low-pass crossover is then switched to 'off,' and the crossover functions and bass level duties are handled by the system electronics, as with any powered subwoofer.

Several design features distinguish 28 SUB's amazing performance--its powerful, long-throw woofers, its solid 1"-thick (!) resonant-free MDF baffle, and its audiophile-grade crossover.

This is one serious subwoofer.

The SA-180 monoblock amplifier is the perfect companion to the 28 SUB. With 180 watts of rock-solid RMS power, a massive toroidal transformer, 12-volt trigger turn-on, and 3-position equalization switch, the SA-180 has all the right moves to make the 28 SUB perform at its best.

Requires SA-180 and GFR-626

Rated for Medium Rooms
View Room Size Ratings




In-Wall and In-Ceiling Speakers

Feature List

  • Dual heavy-duty long-throw 8-inch woofers 
  • Solid, resonance-free MDF baffle
  • Built-in, defeatable low-pass filter 
  • IR knockout 
  • Requires GFR-626 Grille/frame assembly (sold separately)
ico_pdf.gif Manuals
ico_pdf.gif Brochures
ico_pdf.gif Installation
ico_wm.gif Video

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Specifications IWTS-28 SUB

Model IWTS-28 SUB 
Type  In-Wall Subwoofer
Woofer  (2) 8" (203mm) heavy-duty, long-throw
Tweeter  N/A
Frequency Response  38-200 Hz +/-3d
Nominal Impedance  Each driver 8 ohms; paralleled together, system is 4 ohms
Crossover Frequency  200 Hz w/built-in low-pass filter
Sensitivity  89dB
Recommended Amplifier Power  30-200 watts RMS
Magnetic Shielding  No
Dimensions w/ grilles (W x H x D)  12 5/16 x 21 5/8 x 3 7/8" (312 x 547 x 100mm)
Cutout Dimensions (W x H) 11 1/8 x 20 3/8" (283 x 518mm)
New Construction Bracket (Optional) IN-NC-626
Weight (ea)  14 lbs (6.36 kg)

SA-180 Monoblock Subwoofer Amplifier Specifications

Model SA-180 Monoblock
RMS Power 180 watts, 4 ohms
Signal to Noise Ratio  
Total Harmonic Distortion 0.05% @ full output
Low Level Input Sensitivity 250mw full output, 100Hz
High Level Input Impedance 15K Ohms
Power Supply Storage 9,400 mfd
Toroid Transformer(s) 400 VA
Peak Output Stage Current 30 amps
Net Weight 14 lbs.
Height 2“ 1.5-U (50mm)
Width 8.5” (215mm)
Depth 12.5" (320mm) including knobs and rear terminals

Atlantic Technology reserves the right to change specifications or appearance at any time without notice.


The IWTS-28 SUB is an in-wall subwoofer that uses dual 8” woofers to deliver rich, vibrant bass to custom-installed audio systems. It is easily retro-fitted to existing construction using Atlantic’s GFR-626 grille/frame assembly, the same grille frame assembly used for the IWTS-30 LCR THX Ultra 2.


The 28 SUB has several features that maximize its flexibility:


As can be expected, the IWTS-28 SUB can be used as the speaker portion of a separately-powered LFE subwoofer in a true 5.1/7.1 system. When used this way, the convenient front-panel switch for the SUB’s crossover would be set to ‘off,’ and the jumpers connecting the two sets of input terminals are left in place. An RCA cable goes from the receiver’s Sub Out jack into a monoblock amplifier (such as Atlantic’s SA-180), and then from the monoblock amp into the 28 SUB. All low-pass/high-pass crossover functions are then handled by the receiver’s bass management system, as when using any powered subwoofer.


However, the 28 SUB has two sets of input terminals (one set for each 8” driver) and an on-board passive low-pass crossover so that it can be driven directly off the front left/right speaker outputs of the system’s receiver—without the need for a separate amplifier. When used this way, the jumpers would be removed and the receiver’s L/R outputs simply connect to the individual  terminals of each of the 28 SUB’s woofers. The 28 SUB’s on-board low-pass crossover—switched ‘on’—ensures that the sub receives only the lower bass frequencies.