My brother and I are building a 5.1 (6 channel) volumecontrol with OPA134, PGA2310, black gate and polypropylene capacitors. We have finally started this project up, the code has been ready in a draft version for the past year! We had to change op-amp model from OPA627 to OPA134 as the OPA627 had to high DC potentiale on the output, and made the volumecontrol 'click' quite much. Note that you have to use a Sony compatible remotecontrol with the 5.1 volumecontrol.
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Picture of the 5.1 volume control pcb before mounting the OPA134 and PGA2310. Software setup: 1) Hold left front button during power on to enter the IR datalink menu. 2) Hold center button during power on to enter IR remote setup menu. 3) Hold right front button during power on to enter default start master volume. 4) Hold left back button during power on to enter firmware menu.