Helix AMPLIFY 204 X-OVER – 24V Edition – 4-Channel Amplifier with Active Crossover for 24 V Vehicles
The AMPLIFY 204 X-OVER – 24V Edition belongs to the 2-Series, the entry point and technical core of the HELIX AMPLIFY platform, which is offered in DIRECT, X-OVER and DSP variants. Its four bridgeable outputs make it suitable for front systems or multi-channel setups, run as 4-channel, 3-channel (with subwoofer) or bridged 2-channel amplifier. This edition is built for trucks, buses and commercial vehicles with a 24 V electrical system, where factory audio is often basic and OEM replacement is restricted.
As an X-OVER model it targets upgrades of factory or aftermarket head units: it offers switchable high-level and RCA inputs, an adjustable active crossover with input mode switch, ADEP.3 for problem-free communication with factory radios, and automatic turn-on. A DirectDSP function lets the input signal bypass the internal crossover, so the amplifier is ready for a later external DSP upgrade.
Key Features
- 24 V power supply technology: designed for upgrading sound systems in trucks and buses
- High output: up to 240 W RMS per channel at 2 Ohms (one channel driven, ≤10% THD+N, 28.8 V)
- Bridgeable outputs: flexible system layouts and higher output, up to 480 W RMS bridged at 4 Ohms (one channel driven)
- Integrated active crossover: high-pass and low-pass filters plus input mode switch for system configuration
- Smart high-level input with ADEP.3: for integration into OEM sound systems without error messages
- Automatic turn-on: switches on via the high-level input
- DirectDSP: routes the input signal unfiltered past the internal crossover to the output stage for use with an external DSP
- Start-stop capability: tolerates short voltage drops (max. 5 s down to 12 V)
- Class D technology: high efficiency and low heat dissipation
- Removable top cover: conceals all connections and controls for a protected, tidy installation; matte, minimalist styling suited to modern interiors
- Compact chassis: for installation in tight spaces
Inputs & Outputs
- 4 x RCA inputs or 4 x high-level speaker inputs (switchable)
- 1 x remote input
- Input sensitivity: RCA 1–8 V, high-level 2–16 V
- Input impedance: RCA 8 kOhms, high-level 9–33 Ohms
- 4 x speaker outputs
Power & Amplifier Section
- 4 x 100 W RMS at 4 Ohms (≤1% THD+N, 28.8 V)
- 4 x 190 W RMS at 2 Ohms (≤1% THD+N, 28.8 V)
- 2 x 380 W RMS bridged at 4 Ohms
- Maximum output (one channel driven, ≤10% THD+N, 28.8 V): up to 240 W RMS at 2 Ohms, up to 480 W RMS bridged at 4 Ohms
- Amplifier technology: Class D
- Frequency response: 10 Hz – 20 kHz
- Signal-to-noise ratio: 99 dB (A-weighted) at full power
- THD at 1 kHz (1 W into 4 Ohms): below 0.012%; THD+N below 0.02%
- Damping factor: 70
- Fuses: 2 x 15 A LP-Mini (APS); power rating 24 V DC, 40 A max.
DSP & Sound Tuning
- High-pass filter: 45–400 Hz, adjustable, 12 dB/oct., can be switched off
- Low-pass filter: 45–400 Hz, adjustable, 12 dB/oct., can be switched off
- Input mode switch for configuring the input routing
- DirectDSP mode bypasses the crossover completely
Installation & Connectivity Notes
- Operating voltage: 21–32 V, for max. 5 seconds down to 12 V
- Idle current: 750 mA
- Operating temperature range: −40 °C to +70 °C
- For 24 V vehicle electrical systems only (trucks, buses, commercial vehicles)
Technical Specifications
| Power RMS ≤ 1% THD+N @ 28.8 V | |
| – @ 4 Ohms | 4 x 100 Watts |
| – @ 2 Ohms | 4 x 190 Watts |
| – @ 1 Ohm | – |
| – bridged @ 4 Ohms | 2 x 380 Watts |
| – bridged @ 2 Ohms | – |
| Max. output power per channel* | Up to 240 Watts RMS @ 2 Ohms Up to 480 Watts RMS @ 4 Ohms bridged |
| Amplifier technology | Class D |
| Inputs | 4 x RCA / Cinch or 4 x Highlevel speaker input 1 x Remote In |
| Input sensitivity | RCA / Cinch: 1 – 8 Volts Highlevel: 2 – 16 Volts |
| Input impedance | RCA / Cinch: 8 kOhms Highlevel: 9 – 33 Ohms |
| Outputs | 4 x Speaker output |
| Output voltage RCA / Cinch | – |
| Signal converter for digital input | – |
| Frequency response | 10 Hz – 20.000 Hz |
| Bass boost | – |
| Highpass | 45 Hz – 400 Hz adjustable (can be turned off) |
| Lowpass | 45 Hz – 400 Hz adjustable (can be turned off) |
| Bandpass | – |
| Subsonic | – |
| Phase | – |
| Slope high- / lowpass | Highpass: 12 dB/Oct. Lowpass: 12 dB/Oct. |
| Slope subsonic | – |
| Slope subsonic / lowpass | – |
| Signal-to-noise ratio (A-weighted) | 99 dB @ full power |
| Distortion (THD @ 1 kHz, 1 W into 4 Ohms) | < 0.012% |
| Distortion (THD+N @ 1 kHz, 1 W into 4 Ohms) | < 0.02 % |
| Distortion (THD @ 100 Hz, 1 W into 4 Ohms) | – |
| Distortion (THD+N @ 100 Hz, 1 W into 4 Ohms) | – |
| Damping factor | 70 |
| Operating voltage | 21 – 32 Volts (max. 5 sec. down to 12 Volts) |
| Idle current | 750 mA |
| Fuse | 2 x 15 A LP-Mini-fuse (APS) |
| Power rating | DC 24 V ⎓ 40 A max. |
| Operating temperature range | -40 °C to +70 °C |
| Additional features | Active, adjustable crossover, input mode switch, Start-Stop capability, highlevel input with automatic turn-on function, ADEP.3, DirectDSP function |
| Dimensions (H x W x D) | 41.5 x 248 x 118 mm / 1.63 x 9.76 x 4.65” |
* One channel driven (≤ 10 % THD+N @ 28.8 V)
Scope of Delivery
1 x Amplifier HELIX AMPLIFY 204 X-OVER – 24V Edition
2 x Allen key
3 x Connection cable
2 x Fuse
1 x Mounting material
1 x Instruction manual
