in the other question about the "popp" sound I asked if the "popp" is harmful to a loudspeaker. Since I am also interested in the "why" on the circuit level, here is my next question. I put this question here and not in the audio design part because I think the problems also apply to other power amplifiers beneath these for audio systems.
So...what is the reason?
CoreyF answered to my previous question, that professional audio equipment uses power sequencing systems to turn on the components of such a system one after the other and the amplifier in the end. (And here starts my interpretation) This helps to avoid these loud sounds / the surges that are generated by switching processes of other compoinents to be amplified and supplied to the loudspeakers.
But if I am right that means that the surge itself is initially generated by other components than the amplifier (e.g. the mixing console), right? The amplifier only amplifies the already generated surge.
If my assumptions from above are correct, how do I avoid these surges in non-professional audio systems? For example: My active loudspeakers I have here make a "popp" whenever you switch them on or off (the attached audio source is already up when I switch them on or off, so no surge comes from there).
That means, the "popp" comes from the circuits inside the loudspeaker.
My intention is to modify the loudspeaker in such a way that it doesn't make these "popp" sounds any more, but for that I want to understand, where the sound comes from (where the surge is generated).
Since there are three different situations in which a popp occurs, here are my three "problems":
I can imagine that the sudden connection of the supply to the AC mains is responsible for an initial voltage peak/transient that is amplified by the amplifier (am I right here?). To solve that I plan to use a "soft start" circuit, using a timer and a relay which connect the rest of the circuits after a short delay to the supply.
Why does the active loudspeaker "popp" when I switch it off? That "popp" also occurs not immediately when I push the switch (when I switch off the AC), but after 2 seconds or so, after I switched it off. So it is not a (direct?) surge that the switching generates.
When I push the switch and let it go, the LED at the front fades out, so I think some capacitors are discharging. As soon as the LED is close to be dark, the switch-off "popp" occurs. Where does that surge come from / what is the reason? My initial idea to overcome that surge is to monitor the secondary AC side of the transformer and disconnect the drivers from the amp as soon as the AC signal falls off (and optionally the amp from the supply).
Whenever I accidentally disconnect the loudspeaker from the mains without switching it off using the front-panel switch, a really loud "bang" occurs. That bang also occurs immediately when the power falls off, in contrast to the delayed "popp" when I use the front panel switch (see 2).
Why is it louder when I switch off the mains instead of using the front panel switch? From my point of view I assume, that the front panel switch only disconnects the secondary side of the transformer from the capacitors of the supply, which reasons the discharging and the difference in the switch-off process "popps/bangs".
Additionally I assume that the sudden power loss generates a high voltage at the transformer's secondary due to it's inductance.
Which of my ideas and guesses are wrong or right?