Soundcard Menu

The wizard searches for soundcard controls using the default names Windows uses. The soundcard driver may not offer controls with the default names, in that case the names the wizard has found are listed in the soundcard menu and may be selected manually, the choice is remembered for subsequent startups. The control names are usually those shown on the controls in the Windows mixer.

Volume Control Name
The volume controls are used for setting input and output levels. The wizard remembers the settings the controls had when it started and restores them when it exits.
Balance Control Name
Balance controls (if they exist) for the selected input and output are set to their mid-point position. Their original settings are restored when the Wizard exits.
Select Control Name
The select controls are used to enable the chosen audio input and disable all other inputs - soundcards typically allow only one input to be selected at a time, but the Wizard attempts to deselect all other inputs anyway.
Mute Control Name
The mute controls are made available in the Signal Generator panel, the Wizard unmutes the wave and output controls when it starts up but ignores them thereafter, if you subsequently mute the output it will remain muted until you unmute it. If your soundcard has a true line output it will usually not be affected by the output mute control, muting this control may be required to stop the test signals being played out on the PC's internal speakers. All other replay sources are muted.
Wave Control Name
The test signals generated by the Wizard are routed to the Wave output, the wave volume control (if found) is set to full scale and the balance control (if found) is set to its mid-point. The original settings are restored when the Wizard exits.
Sample Rate
The sample rate may be set to 48kHz or 44.1kHz. The default is 48kHz. Note that the lists of input and outout devices only include those devices that report they support the selected sample rate, if your device does not appear in the lists try changing the sample rate.
Measure Soundcard Response
Measure the response of the soundcard with the Right lin output looped back to the Right line input. The measurement is used to generate a soundcard calibration file.
Save Soundcard Measurement as Cal File
Save the current soundcard measurement data as a text file, with the SPL values offset to give 0dB at 1kHz. The file is automatically loaded and applied to subsequent measurements.
Load Soundcard Calibration File
Loads a set of calibration data to compensate for the soundcard's frequency response. The calibration file is a plain text file which by default has the extension .cal, though other extensions are also accepted. It should contain the actual gain (and optionally phase) response of the soundcard at the frequencies given, these will then be subtracted from subsequent measurements. The values in the calibration file can be separated by spaces, tabs or commas.

Here is an example of a valid file format:
Soundcard Calibration data saved by Room EQ Wizard V3.26
Source: SoundMAX Digital Audio, Wave Out Mix, Right channel, volume: 0.075
Format: 48000Hz sampling, Log Swept Sine, 176ms pre-impulse, 1,000ms post-impulse 
Dated: 28-Nov-2005 17:19:51
Sample Rate: 48000

0 -9.38
1 -7.69
2 -6.34
3 -5.22
4 -4.26
5 -3.48
6 -2.80
7 -2.20
8 -1.71
9 -1.28
10 -0.87
11 -0.55
12 -0.25
            
After a calibration file has been loaded it wil be applied to all subsequent measurements. Loading the calibration file does NOT affect any data already measured and does not affect any measurement data that is imported. The graph display is updated to show the calibration curve, offset to lie at the centre of the graph window.

Linear interpolation is used between calibration points. Outside the range of the calibration data the behaviour depends on whether C weighting compensation has been selected. If C weighting compensation is selected, C weighting curve figures will be used for frequencies above or below the range of frequencies in the calibration data. If not, the calibration values for the lowest frequency in the file will also be applied for all lower frequencies and the calibration values for the highest frequency in the file will be applied for all higher frequencies.

The calibration file name and path are remembered for the next startup, the file will be loaded automatically when the Wizard is opened. A message confirming loading of the file is given.

To stop calibration data being applied, use the "Clear calibration data" option.

Useful tip: To apply or remove a soundcard calibration file to a measurement after it has been taken, simply load or clear the cal data as required and press the Apply Windows button in the Impulse Response Controls graph group to recalculate the frequency response.
Clear Calibration Data
Clears the calibration data structures, all subsequent measurements will not have any soundcard calibration corrections applied to them and the Wizard will not load any previously specified soundcard calibration file on the next startup.
Generate Soundcard Debug File
This entry generates a text file with information about the soundcards found and the formats and controls they support. If there are problems configuring the soundcard for use with the wizard provide a copy of this file along with a description of the problem.

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