Spin Semiconductor

When I first power up the FV-1 (into a "live" amp) it makes a rushing white noise, which tapers down to '0' in about 3-seconds. Is this normal, or should I consider a turn-on mute circuit for my product ?

The FV-1 has an internal mute circuit so it shouldn't be putting out any rush of noise at power-up. But if the 3.3V rail comes up slow that could cause the part to not reset quickly (problem with all digital circuits) or if the xtal used has any start up issues (15pf cap in example schematic from X2 to gnd can address this issue) then it may generate noise. Check power rails and xtal to start.

I'll reduce my filter cap values on the 3.3 supply, and add that 15-pf cap.

It works without, but now we know why we should have it....