SMD single-ended to balance headphone amp
Greetings. Here is a little (literally) headphone amplifier design I have been working on. By little, I mean mostly surface mount with a board size of 3.75" x 2.35". Fits nicely inside the board size limitation for Eagle layout freeware license version. It takes a single ended input and provides a balanced output. I will post lots of additional information tomorrow. Just wanted to get it out there so people could start looking at it. Also, please post if you see any mistakes or something that could be done better.
Important: Design contains Jan Meier's crossover circuit. I have asked him permission to post this schematic and pcb layout. He graciously agreed. But one caveat: Neither me nor anyone else may mass produce and/or sell this design. Not even for just DIY boards sold at cost.
I do have one question for the group: What would be a good J-FET for power supply filtering like the PPA? Looks like it will need roughly 50mA for all the opamps (not buffers). Need to be sure it can handle the current and voltage drop near Idss, electrically and thermally. The intended rails are +-12Vdc.
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