Helix AMPLIFY 204 DIRECT – compact 4-channel amplifier for DSP systems
The AMPLIFY 204 DIRECT belongs to the HELIX AMPLIFY 2-Series, a range of specialized amplifiers each built for a particular application. The 204 offers four bridgeable channels and can run as a classic 4-channel system, as 3 channels with a subwoofer, or as a bridged 2-channel amplifier. Made for HELIX DSP, the DIRECT variant is intended for pure signal transmission from external DSPs, whereas its sibling, the X-OVER, has an integrated active crossover.
The DirectDSP input dispenses with conventional input filtering to preserve signal integrity, and the minimalist input architecture keeps noise and distortion low. A high-quality gain stage with clipping LED allows precise level matching, and a stereo/mono switch on each input pair allows bridged operation from a single RCA signal without Y-adapters. For the AMPLIFY 2-Series as a whole, Audiotec Fischer promises sound and output above its class, with brilliant, precise treble, controlled mids and tight, powerful bass.
Key Features
- Four Class D channels: 4 x 100 W RMS at 4 Ohm or 4 x 190 W at 2 Ohm; up to 240 W RMS per channel at 2 Ohm (one channel driven).
- Bridgeable outputs: 2 x 380 W RMS bridged at 4 Ohm, for 4.0, 3.1 or bridged 2-channel layouts.
- DirectDSP inputs: no conventional input filtering, for pure transmission of DSP signals.
- Stereo/mono switch: per stereo input, enabling bridged operation from one RCA signal without a Y-adapter.
- Gain stage with clipping LED: for precise level adjustment.
- Low-noise input architecture: minimalist design to keep noise and distortion low.
- Start-stop capability: uninterrupted operation down to 6 V supply voltage.
- High efficiency: Class D with low heat dissipation.
- Very compact housing: space-saving for tight installation locations; surface-mounted device (SMD) technology.
- Removable top cover: conceals connections and controls; matte, minimalist design.
Inputs & Outputs
- 4 x RCA inputs (DirectDSP), sensitivity 1–8 V, input impedance 67 kOhm
- 1 x remote input
- 4 x speaker outputs
Power & Amplifier Section
- 4 x 100 W RMS at 4 Ohm, 4 x 190 W RMS at 2 Ohm, 2 x 380 W RMS bridged at 4 Ohm (≤1% THD+N at 14.4 V)
- Max. output (one channel driven, ≤10% THD+N at 14.4 V): up to 240 W RMS at 2 Ohm, up to 480 W RMS bridged at 4 Ohm
- Class D amplifier technology
- SNR 99 dB at full power (A-weighted); THD below 0.012%, THD+N below 0.02% (1 kHz, 1 W into 4 Ohm); damping factor 70; frequency response 10 Hz–20 kHz
- Fusing 2 x 30 A LP-Mini (APS); max. 70 A at 12 V DC; idle current 1,100 mA
Installation & Connectivity Notes
- Operating voltage 10.5–16 V (max. 5 s down to 6 V), start-stop capable
- No crossover or filters on board – crossover and EQ are handled by the external DSP
- Operating temperature range −40 °C to +70 °C
Technical Specifications
| Power RMS ≤ 1% THD+N @ 14.4 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 1 x Remote In |
| Input sensitivity | 1 – 8 Volts |
| Input impedance | 67 kOhms |
| Outputs | 4 x Speaker output |
| Output voltage RCA / Cinch | – |
| Signal converter for digital input | – |
| Frequency response | 10 Hz – 20,000 Hz |
| Bass boost | – |
| Highpass | – |
| Lowpass | – |
| Bandpass | – |
| Subsonic | – |
| Phase | – |
| Slope high- / lowpass | – |
| 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 | 10.5 – 16 Volts (max. 5 sec. down to 6 Volts) |
| Idle current | 1,100 mA |
| Fuse | 2 x 30 A LP-Mini-fuse (APS) |
| Power rating | DC 12 V ⎓ 70 A max. |
| Operating temperature range | -40 °C to +70 °C |
| Additional features | Start-Stop capability, Clipping LED, DirectDSP inputs |
| 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 @ 14.4 V)
Scope of Delivery
1 x Amplifier HELIX AMPLIFY 204 DIRECT
2 x Allen key
1 x Mounting material
1 x Connection cable
2 x Fuse
1 x Instruction manual
