Blog › Forums › DIY Amplifiers and Electronics › DSP – how, why, troubleshooting, different hardware, etc. › Reply To: DSP – how, why, troubleshooting, different hardware, etc.
Flipping awesome guide! If I remember rightly, there’s a way to integrate loudness into these boards? Perhaps an offshoot in the schematic with a switch to bypass or not could include this? I think it could be super useful. Although, maybe that should be done as a separate document (or maybe I could do a video on it), as standard implementation is based on old Fletcher Munson curves, whereas it was found out more recently that we hardly need any super high frequency compensation, it’s mostly all about the bass and sub-bass regions. I’d need to figure it out though, it would have to be done with average volume triggers and some kind of prescaler that the user inputs based on the playback volume of a -12dB pink noise signal in their room (a reference volume offset). Nevertheless, I digress yet again… A short comment on how it’s probably best to use a linkwitz Riley crossover over the others since it’s linear in volume level (sums to flat). It also seems like delay is configured in samples, I doubt many people know how to convert s or ms into a number of samples. Not really common knowledge, so maybe a table on how to convert based on sample rate used. I’m not even sure an infrasonic filter is useful on these chips, accuracy of filters starts to decline even below 200Hz on these adau1701s, simply doesn’t seem to be enough processing power for it. I presume it making the filters less accurate is its way of dealing with that. That’s been my experience with the miniDSP non-HD anyways, and that has the same chip. For rePhase, recommendation for setting to 44.1khz rate for best use of the limited samples. As well as limiting optimisation to a -40dB noise floor, and only using the fully parametric phase and filters linearisation tabs so taps aren’t wasted on gain changes, just fixing the minimum phase of filters already applied. I think that’s all it for now. Really professional document, and a job well done!