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Helix Amplify 204 X-Over 24V 4-Channel Fully Bridgeable Class D Amplifier with Active Crossover for 24-Volt Systems
A 4-channel fully bridgeable Class D amplifier from the Helix Amplify 2-Series, the Amplify 204 X-Over 24V delivers 4 x 100W RMS at 4Ω, 4 x 190W RMS at 2Ω, and 2 x 380W RMS bridged at 4Ω (up to 240W per channel maximum at 2Ω) at 28.8V, with 4 RCA inputs, 4 high-level ADEP.3 inputs (2-16V), adjustable active highpass and lowpass filters (45-400Hz, 12dB/Oct, switchable), DirectDSP bypass function, auto turn-on via music signal, 99dB SNR at full power, THD below 0.012% at 1kHz, Start-Stop capability to 12V, and 21-32V operating range specifically for 24-volt truck, bus, and commercial vehicle electrical systems.
Product Overview
The Helix Amplify 204 X-Over 24V is the dedicated 24-volt edition of the Amplify 204 X-Over 4-channel amplifier, sharing identical audio specifications, output power, crossover controls, DirectDSP function, and form factor with the 12V version but powered from a 24V electrical system (21-32V operating range, Start-Stop to 12V). It is specifically engineered for sound upgrades in trucks, buses, coaches, and commercial vehicles on 24V electrical systems where standard 12V amplifiers cannot operate and replacing OEM audio components is often restricted.
Output power is rated at 28.8V: 4 x 100W RMS at 4Ω, 4 x 190W RMS at 2Ω, or 2 x 380W RMS bridged at 4Ω, with maximum output of up to 240W per channel at 2Ω. SNR is 99dB at full power and THD at 1kHz below 0.012%, identical to the 12V version. The fully bridgeable 4-channel architecture supports 4-channel, 3-channel, and 2-channel bridged configurations. The integrated active crossover provides independently adjustable highpass and lowpass filters from 45Hz to 400Hz at 12dB/Oct, both switchable off. The DirectDSP function bypasses the crossover entirely for future DSP upgrade paths. The 4 high-level ADEP.3 inputs (2-16V) with auto turn-on and ADEP.3 circuit ensure seamless integration with factory OEM systems. Four RCA inputs (1-8V) accept aftermarket head units and DSP outputs. Fused at 2 x 15A LP-Mini (APS) for up to 40A at 24V DC.
Features & Benefits
24-Volt Power Supply - Designed for Trucks, Buses, and Commercial Vehicles: The Amplify 204 X-Over 24V operates from a 24V electrical system (21-32V), specifically engineered for trucks, buses, coaches, and commercial vehicles where standard 12V amplifiers cannot be used.
4 x 100W RMS at 4Ω / 2 x 380W RMS Bridged - Flexible Multi-Configuration Output: Identical output to the 12V version: 4 x 100W RMS at 4Ω, 4 x 190W RMS at 2Ω, and 2 x 380W RMS bridged at 4Ω, supporting 4-channel full-range, 3-channel with bridged subwoofer, and 2-channel bridged configurations.
Active Adjustable Highpass and Lowpass Filters - 45-400Hz at 12dB/Oct (Switchable): Independent adjustable highpass and lowpass filters from 45Hz to 400Hz at 12dB/Oct with individual switchable-off capability, providing onboard active crossover control for the full range of truck and bus speaker system configurations without requiring an external DSP.
DirectDSP Function - Crossover Bypass for Future DSP Upgrade Path: The DirectDSP function bypasses the integrated active crossover and routes the input signal unfiltered directly to the output stage, enabling future transition to a DSP-based system architecture without rewiring.
4 High-Level ADEP.3 Inputs with Auto Turn-On - Up to 16V: The 4 high-level ADEP.3 inputs (2-16V) interface correctly with factory OEM head unit speaker load detection systems with auto turn-on from the music signal, eliminating the need for a separate remote wire in factory integrations.
Start-Stop Capability to 12V: Maintains stable operation during voltage drops to 12V for up to 5 seconds during engine cranking events in 24V commercial vehicle Start-Stop platforms.
99dB SNR at Full Power - THD Below 0.012% at 1kHz: Identical audio performance to the 12V version, providing professional-grade audio quality in the 24V commercial vehicle environment.
4 RCA Inputs for Aftermarket Head Units and DSP Outputs: Four RCA inputs (1-8V, 8kΩ) accept line-level signals from aftermarket head units and DSP processors alongside the high-level inputs.
Input Mode Switch: The Input Mode switch selects the appropriate signal routing for the specific system configuration.
Removable Top Cover - Compact 40 x 248 x 114mm Housing: Identical dimensions to the 12V Amplify 204 X-Over for installation in tight truck cab and bus dash locations. Removable top cover conceals connections and crossover controls.
What's in the Box
- Helix Amplify 204 X-Over 24V Amplifier
- 2 x Allen Key
- 3 x Connection Cables
- 2 x Fuse
- Mounting Material
- Instruction Manual
Technical Specs
| Specification | Detail |
|---|---|
| SKU | AMPLIFY 204 X-OVER 24V |
| Brand | Helix |
| Range | Amplify 2-Series |
| Variant | X-Over 24V Edition |
| Channels | 4 (Fully Bridgeable) |
| Amplifier Class | Class D |
| Built-in DSP | No |
| Power RMS - 4Ch at 4Ω (28.8V) | 4 x 100W |
| Power RMS - 4Ch at 2Ω (28.8V) | 4 x 190W |
| Power RMS - Bridged 2Ch at 4Ω | 2 x 380W |
| Max Output per Channel at 2Ω | Up to 240W RMS |
| THD at 1kHz, 1W into 4Ω | Less than 0.012% |
| THD+N at 1kHz, 1W into 4Ω | Less than 0.02% |
| SNR at Full Power | 99dB (A-weighted) |
| Damping Factor | 70 |
| RCA Inputs | 4 x RCA (1-8V, 8kΩ) |
| High-Level Inputs | 4 x High-Level ADEP.3 (2-16V, 9-33Ω) |
| Outputs | 4 x Speaker |
| RCA Preout | None |
| Frequency Response | 10Hz-20,000Hz |
| Highpass Filter | 45-400Hz Adjustable, 12dB/Oct (Switchable Off) |
| Lowpass Filter | 45-400Hz Adjustable, 12dB/Oct (Switchable Off) |
| DirectDSP Function | Yes (Crossover Bypass) |
| Input Mode Switch | Yes |
| ADEP.3 | Yes |
| Auto Turn-On | Yes (via Music Signal) |
| Operating Voltage | 21-32V DC (Stable to 12V for 5 Seconds) |
| Power Rating | DC 24V, 40A Max |
| Idle Current | 750mA |
| Fuse | 2 x 15A LP-Mini (APS) |
| Operating Temperature | -40°C to +70°C |
| Start-Stop Capable | Yes (to 12V) |
| Top Cover | Removable |
| Dimensions | 40mm x 248mm x 114mm |
Compatible With
The Amplify 204 X-Over 24V is compatible with 21-32V DC vehicle electrical systems including standard 24V truck, bus, and heavy commercial vehicle platforms. RCA inputs accept 1-8V from aftermarket head units and DSP processors. High-level ADEP.3 inputs accept 2-16V from factory OEM head units with auto turn-on. This is the 24V edition and is not compatible with standard 12V vehicle electrical systems. Confirm channel bridging configuration and minimum speaker impedance (4Ω for bridged) before purchase.
Frequently Asked Questions
What is the difference between the Amplify 204 X-Over 24V and the standard Amplify 204 X-Over?
Both are identical in audio performance, output power, crossover controls, DirectDSP function, dimensions, and feature set. The 24V edition operates from a 21-32V DC supply for 24V truck and bus electrical systems, is rated at 28.8V, has Start-Stop protection to 12V, and is fused at 2 x 15A at 40A DC 24V. The standard version operates at 10.5-16V for 12V vehicle systems.
Is the Amplify 204 X-Over 24V compatible with standard 12V vehicles?
No. The Amplify 204 X-Over 24V requires 21-32V DC operation. It is not compatible with standard 12V vehicle electrical systems. For 12V installations refer to the AMPLIFY 204 X-OVER.
What is the DirectDSP function on the Amplify 204 X-Over 24V?
The DirectDSP function bypasses the integrated active crossover entirely and routes the input signal unfiltered directly to the output stage, enabling the amplifier to transition from a standalone crossover unit to a clean amplification stage when an external DSP processor is added to the system later without requiring rewiring.
Does the Amplify 204 X-Over 24V auto turn-on from the factory head unit?
Yes. The auto turn-on function activates the amplifier from the music signal via the high-level inputs, eliminating the need for a separate remote wire in factory 24V system integrations.
Can the highpass and lowpass filters be switched off?
Yes. Both the highpass and lowpass filters can be individually switched off for full-range operation on any channel.
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