Click the arrow for the checklist item, the FFT display will appear.
Double check you have your microphones set up for spatial averaging. If using one microphone, place it at the MLP.
Make sure the room is quiet, and touch the "Play" control. A pink noise LFE tone will play through the subs from the Apple TV.
After the plot has stabilized, hit "Pause" and save the plot using the "+" control. You can change the caption if you wish but the time stamp is useful.
Select the lowest or loudest peak on the plot. Place your finger on the screen and move the red line that appears to the center of the peak.
Note the center frequency and the level of the peak over the average level of the overall plot.
Now you're ready to input a parametric filter. Typically it requires the input of the center frequency, a negative gain, and a Q-factor.
Choose half of the peaks level you noted earlier as the gain setting. Be sure to enter a negative number since we want to reduce the peak.
For the Q-Factor use a starting value of 8. A higher number creates a narrower filter. Your goal is to create a negative version of the peak to cancel it.
Implement the filter (some EQs add the filter automatically in real-time). Repeat your measurement and note the change in the shape of the peak.
One of the advantages of the "Scratch Pad" is the ability to compare plots.
If you choose to make incremental measurements (recommended for a beginner), you can see more clearly how the plot responds to the filter.
As you get a better idea of the process, you might consider observing the changes in response while the measurement is running. This is faster.
It's very important to note that dips are not ordinarily EQ-able. This means that try to smooth the plot by cutting peaks rather than lifting dips.
If you try to insert a positive filter for a dip you'll usually see only a minor change in the dip. In this case, take the filter out since it might cause the sub to clip.
You can experiment with the gain and the Q until you see a smooth plot at the center frequency.
We started the process with a smaller gain setting than the peak. Depending on the Q of the peak you might need to adjust that.
Keep in minf we want the Q (width of the filter) to match the actual peak on the plot.
The plot on the left shows that our filter is too narrow and we need a wider Q-factor.
Be careful of too wide of a Q-factor, you might get the allusion that you smoothed the plot but you're not matching the peak parameters effectively.
Until you gain experience, it's a good idea to try to minimize the filter settings; don't over EQ.
You might also see a misshaped peak such as the large peak higher in frequency we see on the left.
This often indicates there are two peaks requiring two filters. This points out the value of a high resolution FFT to perform this process.
When the plot looks similar to the near field plot you took of the sub earlier. You're done.
Touch the return arrow to leave the test. Once back at the checklist, don't forget to touch the check mark and mark the item complete.
