Introduction to the L-Acoustics KS28

The L-Acoustics KS28 is a high-power, dual-18-inch subwoofer designed for large-scale touring and fixed installations. As part of the K Series, it delivers extended low-frequency reinforcement for line array systems such as the K1, K2, and Kara. Understanding its specifications is essential when planning a sound system for stadiums, arenas, festivals, or large clubs.

This article breaks down the KS28 specs in plain terms, explains what each figure means in practice, and offers guidance on integrating the KS28 into a professional audio setup. Whether you are an overseas venue investor or an AV integrator sourcing tested used equipment, this overview will help you make informed decisions.

Key Specifications at a Glance

Below are the core technical specifications of the L-Acoustics KS28 subwoofer.

  • Configuration: Dual 18-inch direct-radiating subwoofer
  • Frequency response (-10 dB): 25 Hz – 100 Hz
  • Frequency response (-6 dB): 29 Hz – 90 Hz
  • Nominal impedance: 2 x 8 ohms (dual voice coil, independently driven)
  • Power handling (AES): 2 x 1250 W
  • Maximum SPL: 143 dB (peak, at 1 m, half-space)
  • Sensitivity: 98 dB (1 W at 1 m)
  • Connectors: 2 x SpeakON NL4
  • Rigging: Integrated rigging system compatible with K Series
  • Dimensions (H x W x D): 570 x 1220 x 780 mm (22.4 x 48.0 x 30.7 in)
  • Weight: 108 kg (238 lbs)

These figures are typical for the KS28 and may vary slightly depending on configuration and measurement conditions. Always refer to the official L-Acoustics documentation for the most current data.

What These Specs Mean in Practice

Frequency Response and SPL

The KS28 reaches down to 25 Hz (-10 dB), which is deep enough for electronic music, live drums, and cinematic effects. Its maximum SPL of 143 dB makes it suitable for large venues where high output is required without distortion. For medium-sized clubs, a single KS28 per side may be sufficient; for stadiums, arrays of 4–8 units are common.

Power Handling and Amplification

The dual 18-inch drivers each handle 1250 W AES, meaning the KS28 can absorb up to 2500 W total. L-Acoustics recommends dedicated amplified controllers (such as the LA12X) that provide the correct presets and power. When using third-party amplifiers, ensure they can deliver the required power per channel and have appropriate DSP for subwoofer crossover and protection.

Physical and Rigging Considerations

At 108 kg, the KS28 is heavy but manageable with proper rigging. Its integrated rigging system allows it to be flown alongside K Series line arrays or ground-stacked. For touring, the KS28’s dimensions are designed to fit standard truck packs. For fixed installations, ensure the structure can support the weight and that the subwoofer is positioned for optimal coupling with the main system.

Integration with Other Equipment

The KS28 is typically used with L-Acoustics K Series line arrays. It can be paired with:

  • K1 or K2 for large-scale touring and stadium events
  • Kara for mid-sized venues and corporate events
  • X Series for smaller installations where extended low-end is needed

When integrating, pay attention to crossover points (usually around 80–100 Hz), delay alignment, and array configuration. Proper DSP presets from L-Acoustics will ensure the best performance.

If you are sourcing equipment for a new venue or upgrading an existing system, consider tested used options. Acoustrade supplies used L-Acoustics subwoofers, line array speakers, and amplifiers that are fully tested and ready for deployment. This can significantly reduce capital expenditure without compromising on quality.

FAQ

Q: What is the frequency response of the KS28?
A: The KS28 has a frequency response of 25 Hz to 100 Hz (-10 dB) and 29 Hz to 90 Hz (-6 dB).

Q: How much power does the KS28 handle?
A: It handles 2 x 1250 W AES, for a total of 2500 W.

Q: What is the maximum SPL of the KS28?
A: The maximum SPL is 143 dB peak at 1 meter in half-space.

Q: Can the KS28 be used with non-L-Acoustics amplifiers?
A: Yes, but you must ensure the amplifier can deliver the required power and has suitable DSP presets for the KS28. L-Acoustics recommends using their amplified controllers for optimal performance.

Q: Where can I buy used KS28 subwoofers?
A: Acoustrade offers tested used L-Acoustics subwoofers, including the KS28, along with other pro audio equipment. Visit our website to browse current inventory.