Quote Originally Posted by Phil Leigh View Post
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What some people are misunderstanding here is that it is the reconstruction filter that recovers the analogue signal, not the DAC. The DAC simply presents the filter with a set of voltages over time. It is within the filter that the sinc function becomes manifest and this is indeed an infinite series - the mathematical definition of a filter is a continuous function over time. A filter is not a step function!
To be clear on this, what comes out of the filter IS a mathematically perfect sine wave...
I read through the paper posted before in the meantime (http://www.lavryengineering.com/docu...ing_Theory.pdf )

Is there any more (hopefully easy to understand) information about how these reconstruction filters work in practice? The paper comes close around page 18, where it is shown how at least the right half of a sinc function can be produced by some circuit.
I'm missing the left part of the sinc function because based on the explanation it is need as well to recreate the original wave-form.

I obviously never cared about how DA converters work, based on the paper I now think of thousands of of sinc-producing circuits which all add up to the final waveform.
Probably this is not how it works in practice but this a missing link for me now to agree that Nyquist theorem and good circuits is all that we need.