hs-28 Dual 18 inch High Output ACM Subwoofer


Our workhorse sub, the dual 18-inch hs-28 deploys our patent-pending ACM (Active Compliance Management) technology, which combines both band-pass and vented alignments into a single enclosure. The hs-28 places two premium, 18-inch transducers into this configuration, with both woofers sharing a common vented chamber. One woofer’s frontal radiation is direct, while the second woofer’s frontal radiation drives the band-pass chamber.

From there we add active onboard electronics including dual monaural powerful amplifiers that send 830W of pure sine wave power (2000W “peak” ) to each woofer. Sophisticated DSP precisely aligns the phase arrivals of the front facing woofer and both vents.

The unique ACM configuration requires a highly-capable transducer. The precision-engineered, long excursion 18-inch woofer developed for the hs-28 features large, 4-inch voice coil for increased power handling and decreased power compression.

The combination of ACM, purpose-designed transducers, and precision electronics allows the hs-28 to deliver much higher output throughout its operating bandwidth from a footprint that’s smaller than most dual 18-inch vented designs.


Rugged Design and Stage Ready

What’s more, the small frontal area and footprint of the hs-28 makes it incredibly easy to assemble compact subwoofer arrays. For example, a stack of six hs-28’s is only slightly more than 6 feet wide by 5 feet high and produces more than 142 dB SPL at one-meter maximum output. The hs-28’s very linear and consistent response makes it an ideal component in directional subwoofer arrays including cardioid stacks and end-fire arrays.

Like all h-Class systems, the hs-28 ships with networking capabilities already onboard. There’s no need for additional cards or retrofitting. SystemVUE uses standard IP protocols to simplify the networking process. Simply plug in and the hs-28 will automatically connect to virtually any kind of IP configuration. Users can then access and monitor network and device-level parameters through our SystemVUE software.

We’ve housed all this rich, subwoofery-goodness in a rugged enclosure that’s manufactured from premium-grade, birch plywood with extensive internal bracing for resonant free operation. A highly-durable, 6-step Dura Coat finish looks great and protects the hs-28 through many years on the road.


hs-28 subs at Bottlerock 2015 in Napa Valley, CA

h-5 High Definition System
h-8 High Definition Full Range System
h-208 Low Profile System
h-12W & h-12N High Definition Systems
h-15W & h-15N High Definition Systems
hm-108A Compact Stage Monitor System
hm-112 High Definition Stage Monitor System
hm-212 High Output Stage Monitor System
hs-20 Dual 10-inch ACM Subwoofer System
hs-25 Dual 15 inch ACM Subwoofer System
hs-28 Dual 18 inch ACM Subwoofer System
hs-221 Dual 21 inch ACM Subwoofer System


  • Portable and installed live performance venues
  • High-impact audio/visual presentations
  • Theatrical sound design
  • World class dance clubs
  • Sound reinforcement rental companies
  • Performing arts centers
  • Themed entertainment facilities


  • Active Compliance Management: Patent-pending hybrid design combines both band-pass and vented alignments into a single, compact footprint for more output and definition.
  • Tons of horsepower: Dual amplifier modules supplies 830W pure sine wave power (2000W “burst” power) to each woofer (4000W ‘burst’ total.)
  • Purpose-designed transducers: Dual spider long excursion woofers features large, 4-inch voice coils for increased power handling and reduce power compression.
  • Standard IP for easy networking onboard: .Simply plug in, and the system automatically connects to virtually any kind of IP configuration.
  • SystemVUE software: Mac, iOS and Windows compatible software provides access to networks and device-level parameters such as speaker protection, input/output levels, volume, mute, delay and input sources.
  • Built for the road: Premium birch plywood enclosure with extensive internal bracing and a highly-durable Dura Coat finish.
  • Impressive output-to-size ratio: Ideal for building extremely high-output and compact subwoofer arrays.


DESCRIPTION Powered dual 18 inch ACM™ subwoofer system
Frequency Response -3dB (+- 1.5 dB) 35 – 80 Hz
Efficiency (1W/1m) 99 dB SPL
Max Peak SPL (band limited pink noise 6 dB crest factor 133 dB SPL half space peak
Max SPL Long Term (SPL @ 1 M before protection Sine Wave) 127 dB SPL Free Field
Coverage Horizontal & Vertical 360 degrees – 6 dB
Amplifier Power (Long Term Sine Wave before protection) LF 1: 830 wattsLF 2: 830 watts
Peak Amplifier Power ( @ 1% THD+N) LF 1: 2000 wattsLF 2: 2000 watts
Amplifier Protection Input limiter, short circuit protection, DC protection of output, intelligent mains fuse protection, power stage overload protection, temperature protection of transformers and heat-sinks
Operational Voltage Universal Mains, 85-268V (dual voltage auto selection). UREC™ power supply provides true universal worldwide mains operation for 120V and 230V, eliminating the need for market specific self-powered loudspeakers and related reliability issues.
THD+N (typical) < 0,05 % (20 Hz – 20 kHz, 3 dB below rated power)
DSP 96k Hz sample rate, mixed-mode 64-bit digital processing, 120 dB dynamic range, less than 600 microseconds latency
Control Network Ethernet / TCP/IP, Fixed IP or DHCP remote monitoring and control
LF Description Dual 18”, paper cone, cloth surround, 4” (100 mm) voice coil, ferrite, 8 Ohm
Inputs Female XLR input with male XLR loop output for both Analogue input and AES EBU digital input (default digital AES channel 1, channel 2 selectable remotely via software). If clock is present system uses AES digital input. System will fall back on analog input if clock is not present. Dante audio over ethernet.
Cabinet Material Multi-ply birch hardwood
Cabinet Finish Black 6-layer coating
Dimensions (H x W x D) 21.18 x 38 x 32.01 in (538 x 965 x 813 mm)
Weight Net: 228.1 lbs (103.46 kg) / Shipped: 259 lbs (117.48v kg)


hs-28 Downloads:

i-Class, is-26, Product Data, Subwoofers August 31, 2016

Dimensional Drawing

ACM Technology


For more information go to the ACM Technology Page

SystemVUE Software

For more information go the SystemVUE product page.


Like all h-Class systems, the hs-28 ships with networking capabilities already on-board. There’s no need for additional cards or retrofitting.  VUE uses standard IP protocols to simplify the networking process. Simply plug in and the hs-28 will automatically connect to virtually any kind of IP configuration. Users can then access and monitor network and device-level parameters through our SystemVUE™ software. The Ethernet connection also allows the use of Dante® for audio transport.