Site Contents
- Introduction
- Audio Data Format
- Interface Applications
- Hardware Specifications
- Data Transmission
- Digital-Analog Converter
- Resetting & Auto-Switching
- History & Characteristics
- Data & Cabling Details
- Coding Format
- Conversion Circuits
- Internal Connection
- External Connection
- Optical Output Circuit
- Transmission Line
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SPDIF: Conversion Circuits
Conversion Of Signal Levels
There are SPDIF and AES/EBU circuits that convert only the signal levels and not protocol level. There is same audio data in both SPDIF and AES/EBU interfaces but in different formats in their sub codes. For example, AES converted to COAX does not become SPDIF and SPDIF converted to XLR is not AES. Changing the transmission medium does not change their native formats. Their working on an application is dependent on the equipment selected. In some DATs there is switch for selecting irrespective of physical interface a particular format. This fixing of physical interfaces in most cases work.
Conversions Using Circuits
Ideas abound for making most common conversions using circuits. There are complete circuits for AES/EBU to SPDIF and vice versa. The circuit for SPDIF to optical is SPDIF/COAX input circuit and optical TOSLINK as output. For Optical to SPDIF, receiver is optical TOSLINK with SPDIF as output buffer circuit. For optical SPDIF to COAX, the TTL output of one optical SPDIF input circuit is to be connected to COAX/SPDIF output circuit. Conversion from CD-ROM digital output to standard SPDIF is done by SPDIF output buffer circuit. For converting CD-ROM digital output to optical, optical TOSLINK output circuit has to be connected to CD-ROM output. For CD-ROM digital output to COAX, a co-axial output circuit is required which can directly connect the digital signal coming from CD-ROM drive. The output circuits though using different components perform basically the same thing.
Building An Adapter
An input circuit that converts inputs like AES/EBU or COAX into TTL format is first required to build an adapter (however if the input itself is in TTL format, no input circuitry is required). Then an output circuit is to be connected with TTL input to get the desired output format. The selected circuit parts can then be attached for getting the conversion circuit. A few output modules can be connected to one input circuitry for multiple outputs.