I’m currently trying to get the hang of electronics and sound production and I come acrosse “impedance issues” from time to time… For instance, “a preamplifier might load the microphone with low impedance, forcing the microphone to work harder and so change its tone quality” or a contact mike having a low amount of bass because its impedance doesn’t suit the amplifier…
Can anyone help me?
In: Physics
Electricity for audio signals is a tradeoff, you want the desired sound with good clarity while minimizing noise. High impedance is one solution to this, where higher voltages and larger currents are used. This tends to overpower electrical noises, but it requires more power. That’s particularly a problem with microphones. Until very recently, batteries sufficient to generate good signals for adequate times were heavy. That’s why you often see tiny microphones tethered to a battery pack clipped to the person’s belt.
Low impedance is a different solution, very small signals, very low resistances, and not batteries. The energy in the sound waves makes the electrical signals, what’s called a sound powered solution. This takes excellent connections, frequent cleaning, and every wire much be shielded to protect from induced currents.
Both solutions can work well, but they don’t mix and match. Or, more realistically, they only mix and match if you have even more expensive gear that can operate in both modes.
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