Dayton Audio OmniMic V2 Precision Measurement System User Manual
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directions. To use these, there must be at least three added curves in the main frequency
response plot, each with different radiation angles assigned. See:
Three different styles of Waterfall graphs can be made from impulse responses. When the
Waterfall button (just to the left of the smoothing control) is pressed, the OmniMic form shows
the impulse response being measured at the bottom of the screen and a Waterfall plot above
it. For more about making Waterfalls, see:
You can also display the phase response of the loudspeaker by selecting the checkbox
shown at bottom right below the frequency response graph. Phase display works with the "only
to" or "blended" options. You can use the delay adjustment (lower right part of the screen) to
specify an amount of delay you wish applied to the phase display. At zero delay, the time
reference is the instant that the peak of the impulse response arrives at the microphone. (Note
that averaging does not operate on phase responses).
Absolute time references: OmniMic always aligns "0 ms" to occur at the highest peak in the
impulse response. Normally, the frequency response calculates from this point forward, and
the peak of the response will be the time reference plane. In advanced mode, you can also
select to have OmniMic start calculation from a different first point. If you wish to see only the
response resulting from a later peak (and if the first "highest" impulse response has decayed
sufficiently by then to not interfere), right-click the mouse on the impulse response at the
starting point of the portion you wish to include.
With some computers, you can play the frequency response test signals (the pseudo noise or
the short swept sine) out from a soundcard in the computer rather than playing the needed
signals from a CD. To enable this, position the mouse over the "status bar" (the horizontal
area at the bottom of the OmniMic window), hold down the "Shift" and the "Alt" keys, and click
the mouse button.
See also
for other ways to play the test signals.