To create a gradual low-pass filter sweep in Fairlight on a Mac, enable Band 6 in the track EQ, select its Low Pass filter, and automate its Frequency parameter. Two keyframes define the sweep; extra points preserve the settings around it.
This walkthrough uses the built-in track equalizer and the controls documented in Blackmagic Design’s September 2026 DaVinci Resolve 21.1 Reference Manual. The task is to make one audio clip gradually sound darker, then hold that filtered sound. You can reverse the frequency values to make it gradually brighter. See the manual’s chapters “Mixing in the Fairlight Page” and “Mix Automation” for the underlying controls. DaVinci Resolve 21.1 Reference Manual
Set up the track and choose the correct filter
Place the audio you want to process on its own timeline track, then open the Fairlight page. A separate track makes the result easier to manage because this workflow automates track processing: other clips on that track encounter the same EQ settings at their timeline positions. Fairlight represents track automation as a line extending across the timeline. Fairlight track automation documentation
Open the Mixer and double-click the target channel’s EQ display to open its six-band equalizer. Enable Band 6, which is off by default, and choose Low Pass as its filter type. Make sure the equalizer itself is enabled. The built-in mixer EQ’s Band 6 supports Low Pass, Low Shelf, Bell, and High Shelf responses. Mixer equalizer controls
A low-pass filter progressively attenuates frequencies above its cutoff. Lowering that cutoff removes more of the upper-frequency content; raising it lets more through. The cutoff is part of a sloping response, so frequencies immediately above it do not suddenly disappear. Audacity’s first-party explanation describes this same filtering principle. Low-pass Filter — Audacity Manual
Choose a filter slope before drawing the sweep. Resolve 21.1 documents slopes from 6 to 24 dB per octave for the mixer EQ’s high-pass and low-pass filters. As an illustrative starting point, try 12 dB per octave, listen, and then compare 24 dB per octave if you want stronger attenuation. Keep the slope constant while you establish the frequency movement so that you can judge one change at a time. Fairlight EQ filter slopes
Draw the gradual frequency change on the timeline
For a sweep with a defined start and finish, drawing individual automation points gives you a clear view of the timing. Fairlight’s automation interpolates between points, so you do not need to draw every intermediate value. Its audio automation points do not have Bézier handles; more elaborate shapes require additional points or a recorded control movement. Drawing mix automation
Display the Band 6 frequency automation
- Click Toggle Automation, to the right of the transport controls. This enables automation recording and playback.
- Locate the automation dropdown beneath the controls in the target track header. It initially shows None when no parameter is displayed.
- Choose EQ → Band 6 → Frequency. If necessary, increase the track height to expose the dropdown.
- Check that you are viewing the intended track’s frequency parameter before adding points. The manual also documents right-clicking a mixer control to display its corresponding automation parameter. Automation view and parameter selection
Once a parameter is selected, Fairlight darkens the clips and shows its automation line. The line becomes green when automation has been drawn or recorded. This view changes the target of editing commands: cut, copy, paste, and delete operate on automation data. Check the selected view before deleting anything. Working in Automation View
Add and adjust the sweep points
Use Focus Mode’s Multi tool. On a Mac, hold Option and click the automation line to add a keyframe. Add a point where the sweep should begin and another where it should end. Drag individual points vertically to change their values and horizontally to change their timing; Fairlight displays a value tooltip during adjustment. Zoom in and increase the track height when positioning points. Adding and adjusting automation keyframes
For a darkening sweep, make the ending frequency lower than the starting frequency. For an opening sweep, make it higher. Watch the Frequency value and EQ response rather than judging direction solely from the height of the automation line.
Place both timing points before making large value adjustments. Then work on each point individually, checking the tooltip. Dragging the line itself can adjust a wider portion of the automation, which is a different operation from moving one point. The manual distinguishes individual keyframe adjustment, whole-line adjustment, and selected-range adjustment. Adjusting the automation line
Use four points to control the sound around the sweep
Two points create a transition. Four points make its surrounding holds explicit. The following is an illustrative design for a ten-second clip; the frequency values are starting choices for auditioning, not measured settings or a preset.
| Position relative to clip start | Illustrative cutoff | Purpose |
|---|---|---|
| 0 seconds | 12,000 Hz | Establish the opening setting |
| 2 seconds | 12,000 Hz | Hold it until the sweep begins |
| 8 seconds | 800 Hz | Finish the six-second sweep |
| 10 seconds | 800 Hz | Hold the filtered ending |
Create the four points at those positions and adjust their values. The equal-value opening pair establishes a hold, the middle pair defines the sweep, and the equal-value ending pair establishes another hold. This arrangement follows Fairlight’s documented interpolation between automation points. Treat the timing and values as an editing plan and refine them by listening. Vector-based automation
If the transition feels concentrated near one end, add an intermediate point inside the sweep and adjust it while listening. Keep the first attempt simple: one extra point is easier to evaluate than a dense series of edits. Fairlight documents building convex or concave automation shapes with several points, rather than using Bézier handles. Creating automation curves
Consider what follows the clip. Moving the last automation point changes the line from that point onward, so the low cutoff can remain in effect for later material on the track. If the next clip needs a brighter setting, add a deliberate return transition before it, or keep that clip on a separate track. Automation line behavior after the last keyframe
Record the frequency movement if you prefer to perform it
You can also record yourself turning the Frequency control during playback. This is useful when the sweep should follow the rhythm of a clip and you would rather shape it by listening. Fairlight can record EQ control changes and then display the resulting automation for editing. Recording mix automation
- Leave Toggle Automation enabled and open Automation Controls.
- Choose Write for a new automation pass and enable EQ recording. Disable unrelated recording categories for this pass.
- Set Touch to Off, then arm only the target track using its automation arm button. The manual documents that an individually armed track records in Latch mode even with Touch set to Off.
- Choose the On Stop behavior deliberately. Event extends the last recorded value to the next existing automation event; Hold removes later automation and holds the final value; Return ramps back to previously recorded values.
- Start playback before the intended sweep and move Band 6’s Frequency control. Stop playback when finished.
- Disarm the track before auditioning. Inspect the recorded curve and adjust individual points if needed. Automation recording modes and individual track arming
For a simple, precisely timed transition, begin with the drawn method. Recording adds choices about touch behavior and what happens when playback stops; those settings matter when existing automation surrounds the new sweep.
Troubleshoot a sweep that stays static or changes abruptly
The EQ stays at one frequency. Confirm that Toggle Automation remains enabled during playback. It controls automation playback as well as recording. Then verify that the displayed curve belongs to the track and Band 6 Frequency parameter you actually adjusted. Enabling and viewing automation
The curve moves, but the filtering is missing. Recheck the equalizer’s enable control, Band 6’s enable control, and the filter type. Band 6 must be active and set to Low Pass for this particular setup. A visible frequency curve alone does not establish those settings. Track EQ controls
The change happens almost instantly. Zoom into the transition and inspect the distance between its points. Spread the start and finish farther apart for a longer sweep. Also confirm that you selected Frequency: switched controls have fixed states and cannot create a continuous frequency ramp. Continuous and switched automation controls
The result changes after moving the clip. Check Fairlight → Automation → Follows Edit. When enabled, automation within an edited clip’s time range follows the edit; when disabled, it stays at its timeline position. Recheck the transition after rearranging clips. Automation Follows Edit
Keep the workflow in the appropriate audio controls
Audacity’s Envelope Tool controls amplitude—volume changes over time. It does not serve as a cutoff-frequency envelope. Its Low-pass Filter documentation describes Frequency and Roll-off settings, so an amplitude fade should not be treated as an equivalent procedure for this sweep. Use Fairlight’s Frequency automation to retain direct control over the changing cutoff. Envelope Tool, Low-pass Filter
Fusion’s Fairlight Animator, introduced in Resolve 21, analyzes audio levels to drive numerical animation controls in Fusion. That documented feature serves audio-driven animation. For the sound-processing task here, use the Fairlight mixer EQ and its track automation. DaVinci Resolve 21 New Features Guide, “Fusion Animation can be Creatively Driven by Fairlight Audio”
Finish by playing from before the first hold through the sweep and into the following material. Keep automation playback enabled, watch Band 6’s frequency movement, and listen for the intended timing. A controlled result has a clear opening setting, a gradual transition, and an ending setting that suits whatever plays next.
Sources
- DaVinci Resolve 21.1 Reference Manual — Blackmagic Design.
- Low-pass Filter — Audacity.
- Envelope Tool — Audacity.
- DaVinci Resolve 21 New Features Guide — Blackmagic Design.