Switching the gain of an audio setup on the fly. Fairly straightforward circuit, lo-noise opamps in noninverting mode, when a gain boost is required a switch parallels another resistor across the ground resistor in the feedback path, increasing the gain of the amp. Gains between 0dB and 12dB, signals about -20 dBu.
Up to now I've been using physical switches, I've trialled automating it by using DOL reed relays instead. With the relays the system suffers from clicks in the output on switching, both ways. I'm investigating obvious causes such as capacitive feedthrough form the coil voltage change, but I'm wondering whether there could be some magnetic effect, where the coil DI/DT induces a voltage *along* the reed, causing the click. The reed is aligned with H, so if everythings 'perfect', this shouldn't occur. In practice, could this be part of the problem?