We started our discussion yesterday on microphonics and how everything in our hi-fi systems can act like a microphone picking up sound in the room and adding it to the music.
So why is this undesirable? Imagine for a moment an extreme version of microphonics. Mentally place a microphone in your listening room, perhaps 15 feet away from your loudspeakers and next to your electronics. Take the output of the microphone and mix it into what you're feeding the power amp driving your loudspeakers. What you get is a time delayed ghost image riding on top of your clean and perfect music.
The time delay happens because of the distance the sound travels before reaching the microphone. The ghost image that is added to the pure music signal is a pale and out of synch version of the real deal. This is real distortion that can make what we cleaned up with a better power supply look pale in comparison.
None the less, this is exactly what's happening in your equipment unless it is in another room because your equipment is chock full of little microphones: capacitors, PC boards, tubes etc.. I suspect most of us are stuck with our hi-fi systems in the same room as our loudspeakers so this is a real problem and one we need to figure out how to minimize.
Tomorrow let's look at some of the ways people minimize microphonics. You may be surprised.