The Channel EQ is a highly versatile #multiband EQ. It provides eight frequency bands, including lowpass and highpass filters, low and high shelving filters, and four flexible parametric bands. It also features an integrated Fast Fourier Transform (FFT) Analyzer that you can use to view the frequency curve of the audio you want to modify, allowing you to see which parts of the frequency spectrum may need adjustment.
You can use the Channel EQ to shape the sound of individual tracks or audio files, or for tone-shaping on an overall project mix. The Analyzer and graphic controls make it easy to view and change the audio signal in real time.
Tip: The parameters of the Channel EQ and Linear Phase EQ are identical, enabling you to freely copy settings between them. In Logic Pro, if you replace a Channel EQ with a Linear Phase EQ (or vice versa) in the same Insert slot, the current settings are automatically transferred to the new EQ.
Channel EQ Parameters
The left side of the Channel EQ window features the Gain and Analyzer controls. The central area of the window includes the graphic display and parameters for shaping each EQ band.
Channel EQ Gain and Analyzer Controls
· Master Gain slider and field: Sets the overall output level of the signal. Use it after boosting or cutting individual frequency bands.
· Analyzer button: Turns the Analyzer on or off.
· Pre/Post EQ button: Determines whether the Analyzer shows the frequency curve before or after EQ is applied when Analyzer mode is active.
· Resolution pop-up menu: Sets the sample resolution for the Analyzer, with the following menu items: low (1024 points), medium (2048 points), and high (4096 points).
Channel EQ Graphic Display Section
· Band On/Off buttons: Click to turn the corresponding band on or off. Each button icon indicates the filter type: Band 1 is a highpass filter.
· Band 2 is a low shelving filter.
· Bands 3 through 6 are parametric #bell filters.
· Band 7 is a high shelving #filter.
· Band 8 is a lowpass filter.
· Graphic display: Shows the current curve of each EQ band.
· Drag horizontally in the section of the display that encompasses each band to adjust the frequency of the band.
· Drag vertically in the section of the display that encompasses each band to adjust the gain of each band (except bands 1 and 8). The display reflects your changes immediately.
· Drag the pivot point in each band to adjust the Q factor. Q is shown beside the cursor when it is moved over a pivot point.
Channel EQ Parameter Section
· Frequency fields: Adjust the #frequency of each band.
· Gain/Slope fields: Set the amount of gain for each band. For bands 1 and 8, this changes the slope of the filter.
· Q fields: Adjust the Q factor or resonance for each band—the range of frequencies around the center frequency that are affected.
· Note: The Q parameter of Band 1 and Band 8 has no effect when the slope is set to 6 dB/Oct. When the
· Q parameter is set to an extremely high value, such as 100, these filters affect only a very narrow frequency band and can be used as notch filters.
· Link button: Activates Gain-Q coupling, which automatically adjusts the Q (bandwidth) when you raise or lower the gain on any #EQ band, to preserve the perceived bandwidth of the bell curve.
· Analyzer Mode buttons (Extended Parameters area): Choose Peak or RMS.
· Analyzer #Decay slider and field (Extended Parameters area): Adjust the decay rate (in dB per second) of the Analyzer curve (peak decay in Peak mode or an averaged decay in RMS mode).
· Gain-Q Couple Strength pop-up menu (Extended Parameters area): Choose the amount of Gain-Q coupling.
· Choose “strong” to preserve most of the perceived bandwidth.
· Choose “light” or “medium” to allow some change as you raise or lower the gain.
· The asymmetric settings feature a stronger coupling for negative gain values than for positive values, so the perceived bandwidth is more closely preserved when you cut, rather than boost, gain.
Using the Channel EQ
The way you use the #ChannelEQ is obviously dependent on the audio material and what you intend to do with it, but a useful workflow for many situations is as follows: Set the Channel EQ to a flat response (no frequencies boosted or cut), turn on the Analyzer and play the audio signal. Keep an eye on the graphic display to see which parts of the frequency spectrum have frequent peaks and which parts of the spectrum stay at a low level. Pay particular attention to sections where the signal distorts or clips. Use the graphic display or parameter controls to adjust the frequency bands as desired.
You can reduce or eliminate unwanted frequencies, and you can raise quieter frequencies to make them more pronounced. You can adjust the center frequencies of bands 2 through 7 to affect a specific frequency—either one you want to emphasize, such as the root note of the music, or one you want to eliminate, such as hum or other noise. While doing so, change the Q parameter(s) so that only a narrow range of frequencies are affected, or widen it to alter a broad area.
Each EQ band has a different color in the graphic display. You can graphically adjust the frequency of a band by dragging horizontally. Drag vertically to adjust the amount of gain for the band. For bands 1 and 8, the slope values can be changed only in the parameter area below the graphic display. Each band has a pivot point (a small circle on the curve) at the location of the band’s frequency; you can adjust the Q or width of the band by dragging the pivot point vertically.
You can also adjust the decibel scale of the graphic display by vertically dragging either the left or right edge of the display, where the dB scale is shown when the Analyzer is not active. When the Analyzer is active, dragging the left edge adjusts the linear dB scale, and dragging the right edge adjusts the Analyzer #dB scale.
To increase the resolution of the EQ curve display in the most interesting area around the zero line, drag the dB scale, on the left side of the graphic display, upward. Drag downward to decrease the resolution.
Using the Channel EQ Analyzer
The Analyzer, when active, makes uses of a mathematical process called a Fast Fourier Transform (FFT) to provide a real-time curve of all frequency components in the incoming signal. This is superimposed over any EQ curves you have set. The Analyzer curve uses the same scale as the EQ curves, making it easy to recognize important frequencies in the incoming audio. This also simplifies the task of setting EQ curves to raise or lower the levels of frequencies/frequency ranges.
The bands derived from FFT analysis are divided on a logarithmic scale—there are more bands in higher octaves than in lower ones.
As soon as the Analyzer is activated, you can change the scaling with the Analyzer Top parameter, on the right side of the graphic display. The visible area represents a dynamic range of 60 dB. Drag vertically to set the maximum value to anywhere between +20 dB and −80 dB.
The Analyzer display is always dB-linear.
Note: When choosing a resolution, be aware that higher resolutions require significantly more processing power. High resolution is necessary when trying to obtain an accurate analysis of very low bass frequencies, for example. It is recommended that you disable the Analyzer or close the Channel EQ window after setting the appropriate EQ parameters. This will free up CPU resources for other tasks.
Logic Studio Effects Manual