Helix ISM 400.2DSP – 2-Channel Subwoofer Amplifier Module with DSP
The ISM 400.2DSP is a compact 2-channel amplified subwoofer module with a 1-channel DSP for modern subwoofer upgrades. It is designed for targeted retrofits in vehicles with factory sound systems without rebuilding the entire system, for converting passive 2 x 2 Ohm IMPACT enclosure subwoofers (ISM-ready) to active operation simply by replacing the connection terminal, and as the basis for custom active subwoofer solutions. It is also suited to hybrid and electric vehicles (EV Ready).
Its Class HD output stage combines Class H and Class D principles: the supply voltage of the output stage follows the signal amplitude, reducing average losses especially at low to medium levels, which results in high efficiency, low heat and a compact form factor. A 64-bit fixed-point audio DSP with high-quality AD/DA converters and the ACO platform (Advanced 32-bit CoProcessor) enable features such as Augmented Bass Processing, DLC, RTC, AISA with InputEQ and TuneEQ, all configured in DSP PC-Tool 6.
Key Features
- High output: 2 x 130 W RMS at 4 Ohms, 2 x 200 W RMS at 2 Ohms, up to 460 W RMS at 2 x 2 Ohms (≤10% THD+N)
- Class HD technology: signal-dependent supply voltage for high efficiency and low heat dissipation
- Smart high-level input with ADEP.3: up to 32 V RMS, for OEM integration without error messages or loss of functions such as fader
- Auto turn-on: via the music signal, independent of the factory amplifier technology
- IMPACT enclosure upgrade: passive 2 x 2 Ohm IMPACT subwoofers become active by replacing the connection terminal; presets in DSP PC-Tool 6
- ACO – Advanced 32-bit CoProcessor: handles control and communication, fast start-up, fast data exchange with DSP PC-Tool and switching between up to ten sound setups
- Augmented Bass Processing: Dynamic Bass Enhancement plus optional SubXpander for more bass at low and medium volume
- AISA and InputEQ: analysis and channel-separated correction of input signals, including factory-applied EQ
- DLC and RTC: Dynamic Loudness Control and Remote Tone Control for volume-dependent adjustment of lows and highs
- TuneEQ: automated adjustment of input, virtual and output EQs
- DirectDSP: routes the input signal unprocessed and unfiltered to the output stage when an external DSP is already used
- EV Ready: start-stop-capable power supply with input range up to 18 V; power save mode
Inputs & Outputs
- 2 x RCA inputs
- 2 x high-level speaker inputs (with ADEP.3 and automatic turn-on)
- Input sensitivity: RCA 0.4–4 V or 0.8–8 V; high-level 1.6–16 V or 3.2–32 V
- Input impedance: RCA 47 kOhms, high-level 9–33 Ohms
- 2 x speaker outputs
- 1 x AISA signal output
- SCP (Smart Control Port) for remote controls and accessories
Power & Amplifier Section
- 2 x 130 W RMS at 4 Ohms (≤1% THD+N at 50 Hz)
- 2 x 200 W RMS at 2 Ohms (≤1% THD+N at 50 Hz)
- Maximum output: up to 460 W RMS at 2 x 2 Ohms (≤10% THD+N)
- Amplifier technology: Class HD
- Frequency response: 10 Hz – 20 kHz
- Signal-to-noise ratio: 102 dB (A-weighted) at full power
- THD at 50 Hz (1 W into 4 Ohms): below 0.005%; THD+N below 0.015%
- Damping factor: 85
- Power save mode: output stages switch off after a period without music signal and wake up in about 2 seconds; delay adjustable or deactivatable in DSP PC-Tool
- Fuse: 1 x 40 A LP-Mini (APS); power rating 12 V DC, 45 A max.
DSP & Sound Tuning
- DSP: 1 x audio signal processor, 64-bit, 295 MHz (1.2 billion MAC operations/s), 48 kHz sampling rate
- Converters: A/D BurrBrown 32-bit, D/A AKM 32-bit
- TuneEQ: automated frequency response correction from one measurement per channel or channel pair with a measurement microphone (e.g. AMI Tuning Kit), using parametric EQ (frequency, Q, gain)
- Augmented Bass Processing: Dynamic Bass Enhancement raises low frequencies and varies the subsonic cut-off depending on the input signal; optional SubXpander adds subharmonics to tones between 50 and 100 Hz
- DeepImpact: dynamic bass restoration – compensates for bass removed by high-pass filtering in factory signals and boosts bass in thin-sounding full-range tracks
- AISA + InputEQ, DLC, RTC and RealCenter based on the ACO platform
- Up to ten switchable sound setups
- Software: DSP PC-Tool 6, including presets for IMPACT enclosure subwoofers
Installation & Connectivity Notes
- Operating voltage: 10.5–18 V, for max. 5 seconds down to 6 V (start-stop capable)
- Idle current: 260 mA
- Operating temperature range: −40 °C to +70 °C
- Additional features: clipping LED, DirectDSP switch, ground lift switch
- Compatible IMPACT 2 x 2 Ohm enclosure subwoofers: IK ES10.1-DVC2 MK2 and IK E8.1-DVC2 MK2
- Compact dimensions and low heat allow flexible installation, also in vehicles with limited current supply
Technical Specifications
| Power RMS ≤ 1% THD+N @ 50 Hz | |
| – @ 4 Ohms | 2 x 130 Watts |
| – @ 2 Ohms | 2 x 200 Watts |
| – @ 1 Ohm | – |
| – bridged @ 4 Ohms | – |
| – bridged @ 2 Ohms | – |
| Max. output power (≤ 10% THD+N) | Up to 460 Watts RMS @ 2 x 2 Ohms |
| Amplifier technology | Class HD |
| Inputs | 2 x RCA / Cinch 2 x Highlevel speaker input |
| Input sensitivity | RCA/Cinch: 0.4 – 4 Volts resp. 0.8 – 8 Volts Highlevel: 1.6 – 16 Volts resp. 3.2 – 32 Volts |
| Input impedance | RCA / Cinch: 47 kOhms Highlevel: 9 – 33 Ohms |
| Outputs | 2 x Speaker output 1 x AISA signal output |
| Output voltage RCA / Cinch | – |
| Frequency response | 10 Hz – 20,000 Hz |
| DSP resolution | 64 Bit |
| DSP power | 1 x 295 MHz (1.2 billion MAC operations/second) |
| Sampling rate | 48 kHz |
| DSP type | 1 x Audio signal processor |
| Signal converters | A/D: BurrBrown 32 Bit D/A: AKM 32 Bit |
| Signal-to-noise ratio (A-weighted) | 102 dB @ full power |
| Distortion (THD @ 50 Hz, 1 W into 4 Ohms) | < 0.005 % |
| Distortion (THD+N @ 50 Hz, 1 W into 4 Ohms) | < 0.015 % |
| Damping factor | 85 |
| Operating voltage | 10.5 – 18 Volts (max. 5 sec. down to 6 Volts) |
| Power rating | DC 12 V ⎓ 45 A max. |
| Idle current | 260 mA |
| Max. remote output current | – |
| Operating temperature range | -40 °C to +70 °C |
| Fuse | 1 x 40 A LP-Mini-fuse (APS) |
| Additional features | Start-Stop capability, Clipping LED, DirectDSP switch, Smart Control Port, 32 Bit CoProcessor, ground lift switch, highlevel input with automatic turn on function |
| Dimensions (H x W x D) | 54 x 231 x 105 mm / 2.13 x 9.09 x 4.13″ |
Scope of Delivery
1 x Subwoofer amplifier module HELIX IMPACT ISM 400.2DSP
3 x Connection cable
1 x USB cable
1 x Fuse
1 x Mounting material
1 x Instruction manual
