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12. Setting Monitor and Subwoofer Levels
Once the stereo monitors and subwoofer are in position, their levels need to be matched. The process is
straightforward and is described below:
Obtain an SPL (Sound Pressure Level) meter, these are very cheap and are now commonly available as
Smartphone/iPhone applications. Set the low-pass filter on the subwoofer back plate to 80 Hz
Send a one octave wide, band-pass pink noise signal to your monitoring system (the main speakers from ERGO, or
from the subwoofer if using the internal crossover). A good choice is 500 to 1,000 Hz band-passed pink noise, which is
within the fundamental frequency range of many vocalists, and minimizes high-frequency problems but doesn't
excite the subwoofer. Adjust your main monitors until you reach a comfortable monitoring level. (Typically 85
decibels SPL using the C response curve on the SPL meter)
Next, route 1-octave, band-passed, bass pink noise to the subwoofer to the monitor system. A good noise choice is 35
to 70 Hz, which is below the 80-Hz frequency of the subwoofer high-pass filter, but sufficiently high enough that
most subwoofers will have adequate response in that band. Set the gain of the subwoofer level control until it
matches the same 85-decibel SPL level. Then, turn up the low-pass filter control on the subwoofer to 130 Hz. This
allows the bass energy between the near-field speakers and subwoofer to overlap.
Listen from the mix position and route pink noise with a band-pass of 80 Hz to 130 Hz to your monitoring system.
Have someone adjust the phase on the subwoofer (ideally a full 360 degrees), and then back, and note the position
which sounds loudest. The loudest position is correct and in phase. Now return the low-pass filter to the 80-Hz
position (or another frequency if you are using external high-pass filters for the near-field speakers).
Your system should now be properly aligned for phase, level and spectral response.
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