Helix C FOUR – high-end 4-channel Class AB amplifier
The HELIX C FOUR is a four-channel amplifier designed for both sound quality and high output. It delivers 4 x 150 W RMS at 4 Ohms or 4 x 220 W at 2 Ohms and can be bridged to 2 x 440 W at 4 Ohms, with a frequency response up to 80 kHz for high-resolution audio.
A custom ultra-low-noise, low-distortion Class A driver stage drives 32 hand-selected MOSFET output transistors (eight per channel), resulting in a damping factor of 1,000 for tight speaker control. A regulated DC/DC power supply keeps output power stable independent of battery voltage, and the optional HDM 2 module adds two optical digital inputs with 32-bit BurrBrown D/A converters.
Key Features
- Class AB broadband design: eight selected MOSFETs per channel, suitable for high-resolution audio.
- Class A driver stage: ultra-low-noise, low-distortion power amp drivers.
- Damping factor 1,000: at 4 Ohms, for tight control of any speaker.
- Regulated power supply: DC/DC switching supply keeps output stages stable regardless of battery voltage.
- Start-stop capability: keeps the amplifier running when the battery drops to 6 V during engine cranking.
- Active crossover: integrated highpass, lowpass and bandpass, 15 Hz – 4,000 Hz, 12 dB/octave.
- Input mode switch: for flexible routing of input signals.
- Optional digital input: HDM 2 module adds two optical S/PDIF inputs (up to 96 kHz) with 32-bit BurrBrown D/A converters.
- Microprocessor monitoring: status monitoring with temperature-controlled fan speed.
- Premium construction: 24-carat gold-plated power and speaker terminals, quad-layer PCB with 70 μm copper traces in SMD technology.
Inputs & Outputs
- Inputs: 4 x RCA/Cinch (sensitivity 1–8 V, input impedance 7.5 kOhms)
- Inputs: 1 x remote in
- Optional via HDM 2: 2 x optical S/PDIF (28–96 kHz)
- Outputs: 4 x speaker output
Power & Amplifier Section
- 4 x 150 W RMS at 4 Ohms (≤1 % THD+N)
- 4 x 220 W RMS at 2 Ohms (≤1 % THD+N)
- 2 x 440 W RMS bridged at 4 Ohms (≤1 % THD+N)
- Max. output power per channel up to 250 W RMS at 2 Ohms in typical multi-channel applications (2-/3-way system + rear + subwoofer)
- Amplifier technology: Class AB with Class A driver stage
- Damping factor above 1,000; frequency response 10 Hz – 80,000 Hz
- Regulated DC/DC power supply with start-stop capability down to 6 V
- Microprocessor-based status monitoring with temperature-dependent fan control
DSP & Sound Tuning
- Highpass, lowpass and bandpass filters, each adjustable 15 Hz – 4,000 Hz
- Filter slope 12 dB/octave
Installation & Connectivity Notes
- Operating voltage 9–16 V; max. 5 seconds down to 6 V
- Fusing: 3 x 30 A LP-Mini fuse (APS)
- Optional HDM 2 digital input module prepares the amplifier for digital sources and HELIX signal processors
- Operating temperature range -40 °C to +70 °C
Technical Specifications
| Output power RMS ≤ 1% THD+N | |
| – @ 4 Ohms | 4 x 150 Watts |
| – @ 2 Ohms | 4 x 220 Watts |
| – @ 1 Ohm | – |
| – bridged @ 4 Ohms | 2 x 440 Watts |
| – bridged @ 2 Ohms | – |
| Max. output power per channel* | Up to 250 Watts RMS @ 2 Ohms |
| Amplifier technology | Class AB |
| Inputs | 4 x RCA / Cinch 1 x Remote In Optional via HDM 2 module: 2 x Optical SPDIF (28 – 96 kHz) |
| Input sensitivity | RCA / Cinch 1 – 8 Volts |
| Input impedance RCA / Cinch | 7.5 kOhms |
| Input impedance highlevel | – |
| Outputs | 4 x Speaker output |
| Output voltage RCA / Cinch | – |
| Signal converter for digital input | – |
| Frequency response | 10 Hz – 80,000 Hz |
| Bass boost | – |
| Highpass | 15 Hz – 4,000 Hz adjustable |
| Lowpass | 15 Hz – 4,000 Hz adjustable |
| Bandpass | 15 Hz – 4,000 Hz adjustable |
| Subsonic | – |
| Phase | – |
| Slope high- / lowpass | 12 dB/Oct. |
| Slope subsonic / lowpass | – |
| Signal-to-noise ratio digital input | – |
| Signal-to-noise ratio analog input | 112 dB (A-weighted) |
| Distortion (THD) | < 0.007 % |
| Damping factor | > 1000 |
| Operating voltage | 9 – 16 Volts (max. 5 sec. down to 6 Volts) |
| Idle current | 2400 mA |
| Operating temperature range | -40 °C to +70 °C |
| Fuse | 3 x 30 A LP-Mini-fuse (APS) |
| Additional features | Active, adjustable crossover, HDM slot, input mode switch, High-Resolution audio, Start-Stop capability |
| Dimensions (H x W x D) | 37.1 x 430 x 240 mm / 1.46 x 16.93 x 9.45″ |
* In typical multi-channel applications (2- / 3-way system + rear + subwoofer)
Scope of Delivery
1 x High-end amplifier HELIX C FOUR
2 x Allen key
1 x Mounting material
1 x Instruction manual
