1. Electronic Audio Signials

Hi there, my name is Max. I am a live audio engineer who is trying to understand some of the theory of audio that is never talked about in live Production.

My question is, when audio runs down a wire (in analog) at say mic or line level, what does it look like. Is the voltage a representation of the amplitude in a an acoustic waveform, and then the frequency of the power is how the pitch is determined? (so if i sent a 1khz test tone down a wire at low volume it would be say 1 volt at 1khz AC, but if i turned up the volume it would be 2 volts at 1khz AC, and if i changed to a 400hz tone it would be 2 volts at 400hz AC)

If that is true where does current (amps) come in?

Thanks so much.

In Christ

MAx

2. Hello, Max,
You basically want a crash course in audio electronics, but I don't think you can get it here. You are generally correct. Amps (Amperes) come from generators, batteries, nuclear power plants, etc. It is the flow of electrons from one atom to another, and down the line from the negitive side to the positive side. Don;t confuse this with amplitude, which is the voltage level of the signal, and that corresponds with the driving signal, guitar, vocal etc. Your assumption of frequency is generally correct also, but something else comes into play (alot of things, actually) and that is frequency v. gain response. Get a book or something on basic electronics is my suggestion. Have fun!

3. Hi Max,
You've got it right. The voltage represents the volume of the signal, and the frequency of the signal is represented by the frequency of the AC signal.

Normally when dealing with the audio, you don't have to worry too much about the current (amperage), except if you are trying to calculate power.

Current is dependant on the resistance (in this case impedance) of the circuit. Impedance is used with AC measurements (can change with frequency ... but a well designed system should be fairly consistant over the audio spectrum).

The formula for current calculations ... I = E/R (I = Amps, E = Voltage, R = Resistance [in this case impedance]). An example would be, if you had a 1 volt signal on a 10K (10,000) ohm line, the amperage would be 0.1 milliamps (0.0001 amps).

When dealing with power, the formula is P = E*I (power=voltage times current).

Hope this helps

4. Voltage represents the signal's volume and the signal's frequency is represented by the frequency shown by the AC signal.

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