This screen includes options that can be applied to the selected audio device's input channels.
Input Source
Some audio devices offer multiple input sources. This section will display the selected input source and, if the device has more than one, allow for the current input source to be changed.
Channel
- Units
Tap Units to select the desired units for the input channel. - Calibrate (...)
Tap Calibrate to manually enter a sensitivity for the relevant input channel, or automatically calibrate its sensitivity based on a known input level.- The current input sensitivity will appear in parentheses after "Calibrate."
- Comp Type (...)
This option will only appear when a miniDSP EARS headphone measurement system is connected and selected as the current input device. Tap this option to select between the 4 different compensation types provided by miniDSP, or to select the Frequency Response Data you have imported in the Frequency Response Compensation menu (for the latter option, select "Other" in the list of compensation types).- The name of the selected compensation curve will appear in parentheses after "Comp Type."
- Frequency Response Compensation
Frequency response (FR) data for a transducer, such as a microphone, may be imported from a text or FRD data file. FR data may also be downloaded from a URL or pasted into a text field. Imported FR data may then be loaded into the selected input channel and optionally applied as a frequency response compensation (FRC) curve.
Loaded FR data may be applied as a frequency response compensation curve in FFT-based spectrum measurements (such as those made by the FFT, Spectrogram, and DFFT tools). Sophisticated interpolation techniques are employed to generate a smooth FR correction curve that matches the loaded data. This correction curve can then be applied to an FFT spectrum of arbitrary length or frequency resolution. FR compensation is not applied to non-FFT-based measurements, such as those made by the Level Meter, Octave analyzer, or Oscope tools.- When FRC is switched on, the name of this item will change to "FR Compensation (FRC Active)."
- If FR data is loaded, but FRC is switched off, this item's name will be "FR Compensation (FRD Loaded)."
- DC Correction
Two options are available for addressing undesired DC offset in input channel data. The first is a DC blocking filter, which will remove the DC component with a first-order high-pass filter. The second options is a DC correction value, which can be used to adjust the DC offset, without filtering the signal. This option is intended to remove DC bias or offset from DC-coupled input channels. Only one of these options can be used at a time.
If a DC correction value is to be applied, it is best to set it before calibrating the input sensitivity for the channel. When using the Auto Set button to automatically calculate and set a DC correction value, it may be best to leave the input channel unconnected, or otherwise connected to a device or circuit that is currently yielding a voltage of 0.- When the DC blocking filter is switched on, the name of this item will change to "DC Correction (Blocking Filter Active)."
- When the DC blocking filter is switched off and the DC Correction is a nonzero value, the name of this item will change to "DC Correction (Offset Correction Active)."