Re: DUOr interference from headphone outputs #eladduo #fdm-duor #duor

Ad Dieleman

I don't think that the interference comes from spurious switching signals from a class D amplifier: the 2.4 MHz signals disappearsĀ completely when loading the output with a low enough resistance, i.e. no high-frequency filtering at all. The filter I applied also doesn't really filter out HF signals, it just loads the output with 4.7 ohm for frequencies over roughly 50 kHz, this being the 3 dB cutoff point. So I still think that the output stage is oscillating under certain circumstances, be it a class D amplifier or something else.

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