Mono Audio I/O

The inputs of both channels are independently amplified from unity to over 1000 times by trim pots accessible from the top of the card. Using sigma-delta modulation, 64 times over-sampling and a 3-stage digital FIR filter, the DBY3 achieves an 80 dB signal-to-noise ratio. The anti-aliasing filters automatically track the sampling rate so that no components have to be changed with the oscillator. There is no external triggering capability due to the nature of sigma-delta converters. A high impedance (1M ohm) is AC coupled but can be converted to DC coupled with a jumper wire across each input capacitor. If the input device requires a +5v bias, such as a telephone handset, a space is provided for a resistor on each channel to supply +5v from a regulated source. This will reduce the input impedance of the board.

Analog Output

The dual channel D/A converters have 8X digital interpolation filters which track the sampling rate set by the on-board oscillator. They are followed by 64X oversampling sigma-delta modulators and ultra-linear low-pass filters which can drive +/-2v into a 600 ohm load.