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Nomad: What are the Units of the Nomad Input Level / Output Level Slider?

Answer

Each channel’s input and output has a variable gain amplifier (VGA) with a gain set by the host software with a number in the range 0 <= N <= 255. In dB, the VGA has a gain (or loss) G given by:

G = 31.5 – 0.5 * (255 – N)

Expressed in linear terms, the linear gain A is:

A = exp10(G / 20)

Where exp10(x) is 10 raised to the power x.

Substituting for G:

A = exp10(1.575 – 0.025 * (255 – N))

For the input, the channel’s overload point, in volts peak-to-peak, is given by:

Vinmax = 1.6 / A

The channel’s output in volts peak-to-peak, for a full-scale source file with a +/-32767 sample amplitude, is given by:

Vout = 1.396 * A

The maximum output level is 1.6 volts peak-to-peak, therefore the maximum VGA gain for a full-scale source file is:

Aoutmax = Voutmax / 1.396 = 1.6 / 1.396 = 1.146

Then, the maximum level setting N for a full-scale source file is:

Noutmax = 255 + ((log10(Aoutmax) – 1.575) / 0.025) = 194

 


Product : Nomad,Nomad