Click to open expanded view
Buy now, pay later
Product features
Helix Amplify 204 X-Over 4-Channel Fully Bridgeable Class D Amplifier with Active Crossover
A 4-channel fully bridgeable Class D amplifier from the Helix Amplify 2-Series, the Amplify 204 X-Over 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), with 4 RCA inputs, 4 high-level ADEP.3 inputs (2-16V), adjustable active highpass and lowpass filters (45-400Hz, 12dB/Oct, switchable), DirectDSP function, auto turn-on via music signal, 99dB SNR at full power, THD below 0.012% at 1kHz, Start-Stop capability, and a removable top cover in an ultra-compact 40 x 248 x 114mm housing.
Product Overview
The Helix Amplify 204 X-Over is the active crossover variant of the Amplify 204 4-channel amplifier, designed as the versatile solution for full-range applications in conventional sound upgrades using factory or aftermarket head units. The fully bridgeable 4-channel architecture delivers maximum installation flexibility: operate as a classic 4-channel system for front and rear speakers, a 3-channel configuration with bridged subwoofer output, or a bridged 2-channel layout for maximum power to a stereo speaker pair or passive subwoofer.
The advanced Class D amplifier stage delivers 4 x 100W RMS at 4Ω and 4 x 190W RMS at 2Ω in 4-channel mode, with maximum output of up to 240W per channel at 2Ω. In bridged mode, two channel pairs each deliver 380W RMS at 4Ω. SNR is 99dB (A-weighted) at full power, THD at 1kHz into 4Ω is below 0.012%, and THD+N below 0.02%.
The integrated active crossover provides independently adjustable highpass and lowpass filters from 45Hz to 400Hz at 12dB/Oct, both switchable off for full-range operation. The Input Mode switch selects the appropriate input configuration for the system. The DirectDSP function bypasses the internal 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 is added to the system later. The 4 high-level ADEP.3 inputs (2-16V, 9-33Ω) and ADEP.3 circuit ensure error-free integration with OEM factory head units. Auto turn-on activates the amplifier from the music signal without a remote wire. Switchable 4 RCA inputs (1-8V) and 4 high-level inputs cover all factory and aftermarket integration scenarios. Operating voltage is 10.5-16V with Start-Stop capability to 6V. Fused at 2 x 30A LP-Mini (APS).
Features & Benefits
4 x 100W RMS at 4Ω / 2 x 380W RMS Bridged - Flexible Multi-Configuration Output: Delivers 4 x 100W RMS at 4Ω, 4 x 190W RMS at 2Ω, or 2 x 380W RMS bridged at 4Ω, providing maximum flexibility to configure the amplifier as a 4-channel full-range system, 3-channel system with bridged subwoofer, or 2-channel bridged high-power layout.
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 provide onboard active crossover control for active front system configurations (separate tweeter and woofer channels) and high/low frequency separation for multi-way setups. Both filters can be switched off individually for full-range operation.
DirectDSP Function - Crossover Bypass for Future DSP Upgrade Path: The DirectDSP function bypasses the integrated active crossover entirely and routes the input signal unfiltered directly to the output stage, enabling the amplifier to operate as a clean amplification stage when an external DSP processor is added. This future-proofs the installation without requiring rewiring or hardware changes when upgrading to a DSP-based system.
4 High-Level ADEP.3 Inputs with Auto Turn-On - Up to 16V: The 4 high-level ADEP.3 inputs (2-16V) connect directly to factory OEM head unit speaker outputs with the ADEP.3 circuit preventing error messages and feature loss. Auto turn-on activates the amplifier from the music signal without requiring a separate remote wire, maximising OEM integration compatibility.
4 RCA Inputs for Aftermarket Head Units: Four RCA inputs (1-8V, 8kΩ) accept line-level signals from aftermarket head units, DSP processors, and external signal sources, providing full system flexibility alongside the high-level inputs.
Fully Bridgeable Multi-Channel Architecture: All 4 output channels are fully bridgeable in any combination, enabling 4-channel, 3-channel, and 2-channel bridged configurations to accommodate a wide range of vehicles and system requirements from a single amplifier unit.
Input Mode Switch for System Configuration: The Input Mode switch selects the appropriate signal routing and input configuration for the specific system setup, simplifying the implementation of various 2-way active, passive, and combined front-subwoofer configurations.
99dB SNR at Full Power - THD Below 0.012% at 1kHz: The Amplify 204 X-Over delivers 99dB SNR at full power and THD at 1kHz below 0.012%, providing audio performance that exceeds conventional 4-channel amplifier standards.
Advanced Class D - High Efficiency and Low Heat Dissipation: The advanced Class D concept delivers high efficiency and very low heat dissipation, enabling 4 x 190W RMS at 2Ω from an ultra-compact 40 x 248 x 114mm housing.
Removable Top Cover - Clean Appearance and Control Protection: The removable top cover conceals all connections, crossover controls, and input mode switches when installed, providing a clean streamlined appearance and additional protection.
Start-Stop Capable - 10.5-16V Operating Range: Start-Stop capable power supply maintains stable operation during voltage drops to 6V for up to 5 seconds.
What's in the Box
- Helix Amplify 204 X-Over 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 |
| Brand | Helix |
| Range | Amplify 2-Series |
| Variant | X-Over (Active Crossover) |
| Channels | 4 (Fully Bridgeable) |
| Amplifier Class | Class D |
| Built-in DSP | No |
| Power RMS - 4Ch at 4Ω (14.4V) | 4 x 100W |
| Power RMS - 4Ch at 2Ω (14.4V) | 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) |
| Clipping LED | Yes |
| Operating Voltage | 10.5-16V (Stable to 6V for 5 Seconds) |
| Power Rating | DC 12V, 70A Max |
| Idle Current | 1100mA |
| Fuse | 2 x 30A LP-Mini (APS) |
| Operating Temperature | -40°C to +70°C |
| Start-Stop Capable | Yes |
| Top Cover | Removable |
| Dimensions | 40mm x 248mm x 114mm |
Compatible With
The Amplify 204 X-Over is compatible with 10.5-16V vehicle electrical systems. 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. The Amplify 204 X-Over has no RCA preout. The DirectDSP function enables future DSP upgrade integration without rewiring. Confirm channel bridging configuration and minimum speaker impedance (4Ω for bridged) before purchase.
Frequently Asked Questions
What is the DirectDSP function on the Amplify 204 X-Over?
The DirectDSP function bypasses the integrated active crossover entirely and routes the input signal unfiltered directly to the output stage of the amplifier. This allows the Amplify 204 X-Over to be used initially as a standalone amplifier with integrated crossover, and later transitioned to a clean amplification stage when an external DSP processor is added to the system - without requiring any rewiring or hardware changes.
What configurations can the Amplify 204 X-Over be used in?
The fully bridgeable 4-channel architecture supports: classic 4-channel operation for front and rear speaker channels (4 x 100W at 4Ω), a 3-channel configuration with two front channels plus one bridged rear channel for a subwoofer (2 x 100W + 1 x 380W), or 2-channel bridged operation for maximum power to a stereo speaker pair or passive subwoofer (2 x 380W at 4Ω).
Can the highpass and lowpass filters on the Amplify 204 X-Over be switched off?
Yes. Both the highpass and lowpass filters can be individually switched off for full-range operation on any channel, providing maximum flexibility for passive speaker configurations that do not require active crossover filtering.
Does the Amplify 204 X-Over work with factory head units without a remote wire?
Yes. The auto turn-on function activates the amplifier from the music signal via the high-level ADEP.3 inputs, eliminating the need for a separate remote wire and maximising compatibility with factory OEM head units.
What is the difference between the Amplify 204 X-Over and the Amplify 204 Direct?
The Amplify 204 X-Over includes an integrated active crossover with adjustable highpass and lowpass filters, ADEP.3 high-level inputs with auto turn-on, and the DirectDSP bypass function for future DSP upgrades. It is designed for conventional sound upgrades with factory or aftermarket head units. The Amplify 204 Direct is designed exclusively as a clean amplification stage for DSP-based systems, with DirectDSP inputs and no onboard filtering.
Recommended for You
- Choosing a selection results in a full page refresh.
!