The HELIX DSP.2 is a digital 8-channel signal processor designed for car audio systems, offering advanced sound processing capabilities and flexible connectivity options. It is manufactured by Audiotec Fischer GmbH.
Function Description:
The HELIX DSP.2 acts as a central hub for managing and optimizing audio signals in a vehicle. It receives audio signals from various sources (pre-amplifier, high-level speaker outputs, or digital optical input), processes them digitally, and then outputs them to external amplifiers. The device allows for precise adjustment of various audio parameters to achieve optimal sound quality. It features an 8-channel pre-amplifier output for connecting power amplifiers. The output voltage is 6 Volts maximum. The remote output is crucial for turning on/off external amplifiers connected to the Line Outputs, preventing interfering signals. This output activates automatically after the DSP's booting process and turns off during "Power Save Mode" or software updates.
Important Technical Specifications:
- Inputs:
- 6 x RCA / Cinch (Line Input)
- 6 x Highlevel speaker input
- 1 x Optical SPDIF (12 - 96 kHz)
- 1 x Remote In
- Input Sensitivity:
- RCA / Cinch: 2 - 4 Volts
- Highlevel: 3.5 - 11 Volts
- Outputs:
- 8 x RCA / Cinch (Line Output)
- 1 x Remote Out
- Output Voltage: 6 Volts
- Frequency Response: 10 Hz - 22,000 Hz
- DSP Resolution: 64 Bit
- DSP Power: 295 MHz (1.2 billion MAC operations/second)
- DSP Type: Audio signal processor
- Signal Converters: A/D: BurrBrown, D/A: BurrBrown
- Signal-to-noise Ratio:
- Digital input: 112 dB (A-weighted)
- Analog input: 107 dB (A-weighted)
- Total Harmonic Distortion (THD+N):
- Digital input: < 0.0008 %
- Analog input: < 0.002 %
- IM Distortion (IMD):
- Digital input: < 0.003 %
- Analog input: < 0.005 %
- Crosstalk: > 90 dB
- Operating Voltage: 9.6 - 18 Volts (max. 5 sec. down to 6 Volts)
- Current Draw: < 480 mA
- Max. Remote Output Current: 500 mA
- Additional Features: HEC slot, Ground lift switch, Control Input, ADEP circuit, Auto Remote switch
- Dimensions (H x W x D): 40 x 177 x 120 mm / 1.58 x 6.97 x 4.72"
Usage Features:
- Line Input (RCA): 6-channel pre-amplifier inputs for connecting signal sources like radios. Input sensitivity is factory-set to 4 Volts (maximum CCW position) and can be varied between 2 and 4 Volts.
- Highlevel Input: 6-channel high-level speaker inputs for direct connection to loudspeaker outputs of OEM or aftermarket radios/amplifiers without pre-amplifier outputs. Input sensitivity is factory-set to 11 Volts (maximum CCW position) and can be varied between 3.5 and 11 Volts. It is crucial to use only the provided pluggable screw-terminal or an optional cable harness from HELIX accessories. Simultaneous use of Highlevel Input and Line Input is strictly forbidden to prevent damage to the car radio's pre-amplifier outputs.
- Optical Input: SPDIF format input for digital stereo signals (12-96 kHz sampling rate). The input signal automatically adapts to the internal sample rate. Volume control for this input is recommended via an optional remote control. It only handles stereo input signals, not Dolby-coded digital audio streams.
- Input Sensitivity Control: Adjusts the input sensitivity for both low- and high-level inputs to match the connected signal source's output voltage. This is not a volume control but for gain adjustment. The range is 2-4 Volts for RCA/Line Input and 3.5-11 Volts for Highlevel Input. Proper adaptation is mandatory to avoid damage. For standard car radios with Highlevel Input, a sensitivity of roughly 9 Volts (8 o'clock position from max. CCW) is recommended.
- Clipping LED: Lights red if any of the analog inputs (Line or Highlevel) are overdriven. It has no function with digital input signals. If it lights up, reduce input sensitivity until it turns off.
- Ground Lift Switch: Galvanically decouples the ground of the DSP.2 signal inputs from the signal outputs, which helps avoid alternator noise. It has three positions: input and output ground separated (center), tied together (left), or connected via a 200 Ohm resistor (right).
- Control Pushbutton: Used to switch between two setup memory positions (press for one second, indicated by a single red flash of the Status LED). Pressing for five seconds erases internal memory (indicated by constant flashing of Status LED), resulting in no audio output until a new setup is loaded.
- Status LED: Indicates the operating mode and active DSP setup. Green means setup 1 is loaded, orange means setup 2 is loaded. A flashing red light indicates no setup is loaded. Blinking orange indicates active internal temperature protection, which first turns off the remote output and then the signal processor if the temperature continues to rise.
- USB Input: Connects the DSP.2 to a PC for configuration using the DSP PC-Tool software (downloadable from audiotec-fischer.com). USB storage devices cannot be connected.
- Control Input: Multifunction interface for optional HELIX accessory products like remote controls, whose functionality is defined in the DSP PC-Tool software.
- Smart Highlevel Input (ADEP circuit): Prevents failure messages and loss of specific features (e.g., fader function) often encountered with OE car radios that diagnose connected speakers. It avoids unnecessarily loading the speaker outputs of the OE radio.
- Start-Stop Capability: The switched power supply ensures constant internal supply voltage even if the battery's voltage drops to 6 Volts during engine crank.
- Automatic Digital Signal Detection: Automatically switches from analog to digital input when a signal is detected on the Optical Input. This feature can be deactivated in the DSP PC-Tool software, or manual switching can be done via an optional remote control.
- HEC Slot (HELIX Extension Card slot): Allows extending functionality by inserting an optional HELIX Extension Card (HEC) for features like Bluetooth® Audio Streaming, an additional optical digital input, an AUX input, or a USB audio input. Installation requires careful handling to avoid damage to the HEC module, signal processor, head unit, or car radio.
Maintenance Features:
- Software Updates: The DSP PC-Tool software for configuring the signal processor is regularly updated and available on the Audiotec Fischer website.
- Power Save Mode: Incorporated in the basic setup, it significantly reduces power consumption of connected amplifiers when no input signal is present for more than 60 seconds. This is particularly useful in modern cars with CAN or other internal bus structures where the radio might remain "invisibly" on for extended periods after locking the car. Once active, the remote output and connected amplifiers turn off. The DSP.2 reactivates the remote output within a second upon music signal detection. The turn-off time can be modified or completely deactivated via the DSP PC-Tool software.
- Temperature Protection: If the internal temperature rises, the Status LED blinks orange, the remote output turns off, and if the temperature continues to rise, the signal processor shuts down until a safe temperature level is reached.
Installation Notes:
- Installation should ideally be performed by an authorized HELIX dealer.
- Always disconnect the battery's negative terminal before installation to prevent damage or injury.
- Install the DSP.2 in a dry location with sufficient air circulation and secure it to a solid mounting surface.
- Ensure no electrical cables, hydraulic brake lines, or fuel tank parts are behind the mounting surface.
- Only use the provided connectors or the optional Easy Plug Cable for connection.
- Plan wire routing carefully to avoid crushing, pinching, or proximity to noise sources.
- The DSP.2 is designed for vehicles with a 12 Volts negative terminal connected to chassis ground.
- The positive cable from the battery for the sound system should have a main fuse within 30 cm of the battery.
- When using the Easy Plug Cable, verify permanent and switched 12 Volts wires with a voltmeter, as they may be reversed depending on the vehicle type.
- For cars with MOST bus structure, the fiber-optic cable must be unplugged from the original radio connector and inserted into the ISO adaptor.
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