| The Forgotten Control |
| In the equalizer section of most consoles there is another set of
controls that is very useful but often ignored - The FILTER controls. Filters remove
signals at certain frequencies and pass on signals at other
frequencies. Normal Equalizer controls reduce (or increase) the
level of a band of frequencies. |
| The frequency response of filters, compared to equalizers is shown in the
illustrations. |
| The red area in the illustration shows the frequencies affected by an
equalizer set to maximum cut at 300 Hz. This could be a setting that an engineer
uses to get "ambiance" out of the cymbal microphone (or cymbal track in
mixdown). The blue response curve shows a filter set to 400 Hz to accomplish the
same thing. The lowest frequency of a cymbal is about 200 Hz. The filter
leaves more of this 200 Hz frequency pass through than the equalizer. The
fundamental of foot-drum leakage into the cymbal microphone is at 50 Hz. The filter
reduces this 50 Hz by a great degree (and the equalizer doesn't remove any of it).
In this specific example, the filter would do a better job. |
| Terms and Applications. |
| The illustration shows a high-pass filter which removes frequencies below
the cut-off frequency and passes frequencies higher than the cut-off frequency. The
high-pass filter can be used to get rid of leakage from the foot drum or bass amp. |
| There are also low-pass filters that pass all frequencies below
the cut-off (and remove frequencies above the cut-off). The low-pass filter would be good
to remove cymbal leakage and hiss (noise). |
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