A Simple Example - miniDSP HA-DSP User Manual

8.11.1 A simple example

We'll use a simplified example of the diagram on the previous page. Only the processing in the DSP chip is
shown, and the bass and treble controls, parametric EQ, cross-feed, and FIR filtering are all lumped into the
block labeled "EQ." For simplicity, the signal is just a sine wave.
Case A
The (digital) signal at the input is full scale – that is, it swings between the –1.0 and +1.0 limits. At the
output conversion, the signal is still full scale, and the DAC chip will output the maximum specified
voltage.
Case B
The EQ stage boosts the full-scale signal, so it exceeds the range –1.0 and +1.0. This is fine internally, as
the DSP has a lot of "headroom" and can represents much larger numbers. At the output stage,
however, the signal must be limited to the range –1.0 and +1.0. Therefore, it is clipped.
Case C
The signal is scaled down in the Input Gain stage, so that when the EQ stage boosts it, it remains in the
range –1.0 to +1.0. Again, there is no clipping at the output stage.
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