Audison C2O Coaxial-to-Optical Audio Converter

The Audison C2O is a compact car-audio interface that converts either a coaxial S/PDIF digital source or an analog AUX source into a TOSLINK optical digital output. It helps connect portable music players and smartphones to a compatible processor or other component with an optical digital input. This makes it useful when the source device and the receiving audio component use different digital connection formats.

The C2O accepts a 75-ohm electrical coaxial S/PDIF signal at resolutions up to 24-bit/192 kHz. Its optical output preserves the incoming digital signal path at up to 24-bit/192 kHz when using the coaxial input. For an analog source, it converts the incoming signal to a 24-bit/48 kHz optical output.

An adjustable analog input stage accommodates source levels from 0.1 to 2 Vrms. The analog AUX input uses a 3.5 mm stereo jack that supports 3-pole and 4-pole plugs, making it suited to many portable devices. Analog-input performance is specified at 0.002% THD, a 5 Hz to 24 kHz bandwidth, and a 105 dB A-weighted signal-to-noise ratio.

The C2O automatically manages its two inputs, with analog AUX assigned priority when both sources are present. When the analog signal stops, it can switch to the coaxial digital input after 6, 9, or 12 seconds; 6 seconds is the default setting. This arrangement can simplify a system using both a portable analog device and a dedicated coaxial digital player.

Its coaxial input includes an isolation transformer intended to reduce susceptibility to electromagnetic interference in a vehicle environment. The compact 69 x 26 x 54.5 mm housing can be positioned close to the source device to keep signal cabling short. It is designed for 6 to 30 VDC vehicle electrical systems and can be activated by a conventional remote signal or a +12V remote connection.

Key Features

• Coaxial-to-Optical Conversion: Converts electrical coaxial S/PDIF audio to a TOSLINK optical output.
• Analog AUX Conversion: Converts a 3.5 mm analog source to 24-bit/48 kHz optical audio.
• 24-Bit/192 kHz Support: Passes compatible coaxial digital sources to optical at high resolution.
• Adjustable AUX Level: Matches analog source levels from 0.1 to 2 Vrms.
• Automatic Input Selection: Gives AUX priority and switches to digital after a selectable delay.
• Isolated Coaxial Input: Uses an isolation transformer to help reduce EMI-related noise.

Design & Installation

The C2O uses a small interface enclosure measuring 69 mm wide, 26 mm high, and 54.5 mm deep, with a listed weight of 0.048 kg. Its connection layout provides a 3.5 mm analog input, electrical coaxial S/PDIF input, and optical output. An internal selector sets the analog-input level and the delay before digital-input activation.

Install the C2O in a dry, protected location with access to the source device and the receiving component's optical input. Use a 75-ohm coaxial cable for a coaxial digital source and a TOSLINK cable no longer than 4.5 m for the optical connection. Confirm that the receiving processor or device accepts the output resolution associated with the selected source, then connect vehicle power, ground, and the appropriate remote turn-on wiring.