Record replay RIAA correction in the digital domain
Scott Wurcer noticed that, when playing records, the signal often gets digitized on its ultimate way to the speakers, through a streaming audio device or a digital multiway crossover or even only for archiving.
Yet the pre-amplification and RIAA correction is still done in the analog domain. So he asked himself: why not do the RIAA correction after digitization? It does have one obvious advantage which is that the filter coefficients, an analog to the R’s and C’s in an RIAA pre-amp, can be specified to an arbitrary accuracy so there is no need for expensive tight-tolerance parts. And, once archived unequalized, music can be later processed with any desired correction curve opening up a new level of flexibility to the user.
His article gives the tools and methods to do it, the pitfalls to look out for and tabulates the DSP filter coefficients for implementation of various historical ‘RIAA’ curves on a simple, low cost platform like a miniDSP.