Setting the signal level the Wizard uses during measurement involves
generating a pink noise calibration signal and adjusting the AV
processor's volume control and/or the calibration signal level so that at
the measurement point (usually ear height at your main listening position)
your SPL meter shows a level of around 75dB.
Press the
button in the Signal Generator panel and follow the instructions on screen.
The test signal is generated at an RMS Level of -20dB. If connected to an AV
processor, start with the volume fairly low and increase it until the meter
is reading around 75dB. The exact level is not critical. If connecting directly
to an equaliser such as the BFD, use the control the Wizard provides during the
setting process to change the level of the generated signal. In either case, the
final signal generator level will be used for subsequent measurements - remember
to use the same AV processor volume setting whenever measurements are made.
Note that the measurement level can be altered manually by changing
the value in the Measurement Level box above the button.

- The Wizard sets the soundcard's wave volume to full scale and
the output volume to half scale. The volume controls are not altered
in the level setting process, levels are controlled by scaling the
digital data for the signals generated. On exit the Wizard restores
the wave and volume levels that were in use when it started up.
Trouble-shooting tip: To prevent the Wizard from
altering the volume controls, select the output device but do not
select an output, i.e. leave the selector set to "Choose output..."
The actual output used and any level control settings will then need
to be made using the Windows volume control or the soundcard's mixer.
See below for an example of suitable settings
- If the names of the sources and volume controls are not the
standard Windows settings (wave and volume) the names the soundcard
driver uses can be chosen from the Soundcard menu - setting
the measurement level should be repeated after doing that
- The output volume control will usually have no effect on the
level of line outputs, but will affect a headphone output or the
PC's speakers - if using a true line output for the measurement
signal the output volume control should be muted to prevent the signal
being heard from the PC's own speaker(s).
- The range of the wizard controls is 0..1, but the underlying
gain controls in the soundcard are generally logarithmic. If you use
the wizard to alter the volume control settings using the arrows on
the spinners, the settings will change in increments corresponding
to 0.5dB, however the soundcard's own controls will usually have
lower resolution, so changes may have no effect on the output until
the next step in the soundcard's control is reached.
- Changes in volume settings outside the wizard (e.g. in the
Windows mixer) are automatically detected and reflected in the wizard's
controls.
- The Wizard automatically mutes all playback sources other than Wave when
it starts up, to eliminate noise or sounds from other sources.
This only happens if an output has been chosen from
the "Choose output..." list. It is particularly
important to mute the input used for the signal from the SPL meter (usually
Line In), otherwise a feedback loop results as the signal picked up by
the SPL meter is fed directly back to the output. The original mute states
are restored when the Wizard exits. Here is an example of correct playback
control settings, only Wave is unmuted, the Wave volume is full scale and
the output volume is half scale.
After setting the Measurement Level the next step is to
set the input volume control.
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