I built this board for my active speakers to work as an active crossover. However, noticed that there are some flaws in design. First, the input capacitors to audio ADC are too small - the input RC makes a first order high pass filter with F3 about 80 hz (18k external + internal2k impedance with the 100 nF input cap). That is easy to fix. Then the design is quite a bit over engineered regarding the control A/D section, the op amp maybe helps giving a more linear values but you can do without. Instead it would be nice to have active output filtering. Anyway, it's easy to build and mod because of the large PCB area.
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