HELIX ISM 400.2DSP - 2-Channel Amplified Subwoofer Module with 1-Channel DSP | 2x2Ω Stable

ISM 400.2DSP – 2-channel subwoofer amplifier module with integrated DSP

The ISM 400.2DSP is a powerful 2-channel subwoofer amplifier module with an integrated 1-channel DSP – making it a compact high-performance innovation for modern subwoofer upgrades. It combines strong amplification, precise digital signal processing, and a space-saving modular design to create an active subwoofer solution that integrates cleanly into the vehicle and delivers controlled, punchy bass. Thanks to its EV-Ready architecture, it is also suitable for today’s hybrid and electric vehicles.

The smart module for targeted subwoofer upgrades

The ISM 400.2DSP is focused on targeted subwoofer retrofits in vehicles with factory sound systems – whenever an additional subwoofer needs to be integrated cleanly and reliably without rebuilding the entire system. It is especially attractive where installation space and effort are limited, but a high-quality, precise bass upgrade is still required. The ISM solves this by bundling amplification, DSP, and intelligent integration specifically for this use case: it delivers up to 460 W RMS maximum power at 2 × 2 Ω for strong power reserves, and the heavy-duty stereo highlevel input (up to 32 V RMS) enables safe signal pickup in systems with OEM amplifiers, while ADEP.3 supports error-free integration with modern factory head units. The integrated signal-sensing turn-on function also ensures reliable power on/off, regardless of the technology used in the factory amplifier. With the integrated DSP, you get the foundation for controlled subwoofer integration – tuned to installation position, vehicle acoustics, and the desired bass character. In addition, the DirectDSP function offers a practical option: when needed, the input signal can be routed directly to the power stage without DSP processing. This is ideal when an external DSP is already in the system and the ISM is used purely as a powerful subwoofer amplifier. Thanks to its compact concept, the ISM is also an excellent basis for custom-built active subwoofer solutions.

Power, efficiency and precise sound tuning

For demanding subwoofer applications, the ISM 400.2DSP delivers plenty of power in a compact format: 2 × 130 W RMS at 4 Ω, 2 × 200 W RMS at 2 Ω, and up to 460 W RMS maximum power at 2 × 2 Ω – an ideal foundation for ambitious bass upgrades. To achieve high efficiency and extremely compact dimensions, the ISM 400.2DSP uses Audiotec Fischer’s Class HD concept. It combines the benefits of Class-H technology with the principle of a Class-D amplifier. The internal supply voltage of the output stages is continuously adjusted depending on signal amplitude, which drastically reduces average power losses, especially at low to medium output levels. The result is outstanding efficiency, low heat generation, and a particularly compact subwoofer module format. For signal processing, an extremely powerful 64-bit fixed-point audio DSP is used in combination with high-quality AD/DA converters – the basis for clean signal handling and precise bass integration. With DSP PC-Tool 6, you have access to the full range of modern DSP tools and tuning options to tailor the subwoofer to the vehicle, installation position, and personal sound preferences.

DeepImpact – Dynamic bass restoration

With the ISM 400.2DSP, we introduce our DeepImpact DSP algorithm for dynamic bass restoration. Regarding signals from factory sound systems, DeepImpact compensates bass loss caused by applied high-pass filtering and reconstructs missing low-frequency content. With full-range signals, DeepImpact reacts dynamically to the source material: if a track lacks impact in the lower frequency range, the algorithm boosts the bass in a targeted way to deliver a fuller, more powerful sound.

Efficient integration thanks to IMPACT enclosure subwoofer compatibility

The ISM 400.2DSP allows “ISM-ready” passive 2 x 2 Ω enclosure subwoofers to be converted into an active solution by simply replacing the connection terminal. For an efficient start into sound tuning, suitable presets for IMPACT enclosure subwoofers are also available in DSP PC-Tool 6.

EV Ready for modern vehicle platforms

For maximum compatibility and everyday usability, the ISM is “EV Ready” and can be used in hybrid and electric vehicles without issues. The start-stop capable power supply with an extended input voltage range up to 18 V ensures stable operation in modern vehicle architectures with different powertrain concepts – especially in vehicles where maximum current draw is often limited. Thanks to very high efficiency, heat generation and space requirements remain low, further supporting flexible installation concepts.

ACO – Advanced 32 Bit CoProcessor platform

Rapid processing power beyond the signal path – the high-performance 32 Bit ACO platform handles all control tasks and ensures ultra-fast data communication with the DSP PC-Tool software, including lightning-fast switching between up to ten sound setups. But ACO offers even more: integrated features like Augmented Bass Processing, RealCenter, Dynamic Loudness Control (DLC), and Remote Tone Control (RTC), along with the new Advanced Input Signal Analyzer (AISA), provide unmatched tuning versatility and allow analysis and compensation of input signals from factory sound systems that already contain sound settings.