Audio typically uses dBm to describe power, which is usually referenced to 600Ω.Why exactly do we use 600 ohms or 60 ohms as expalined in the artcile? I mean how do we decide the load and the power across it?
Practically speaking, how the audio that we listen to is calibrated?
Explain your rational for using a factor of 20 instead of 10 in this example. In other words, where is the square?Decibels is a general purpose technique for measuring practically anything. For example if you want to know the relationship of the US national debt to the median family income, you proceed as follows:
I get approximately 171 dB
- Form the ratio of the US national debt (≈ $18,418,630,000,000) to the median family income for 2014 (≈ $53,657)
- Take the logarithm to the base 10
- Multiply by 20
Your mileage may differ and it is growing by the second.
The 600Ω standard has nothing to do with 70V loudspeaker lines.Generally, audio has 2 ohms, 4 ohms and 8 ohms for speakers.
With PA - Public Announcement - transformers are used on a high voltage line, typically 70V, to run each speaker. Think Show Day.
These are usually 600 ohm.
That is, impedance matching 600 ohm line to 8 ohm speaker.
If you are doing a UNI course, you are expected to figure this out.
Voltage and current ratios use a factor of 20, whilst power ratios use a factor of 10 because power is proportional to voltage squared or current squared. If you want to use a factor of 10 for dollar ratios I don't think I could present a cogent argument against it, except, by analogy to power, why are dollars proportional to something squared.Explain your rational(e)[Sic] for using a factor of 20 instead of 10 in this example. In other words, where is the square?
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by Luke James