How to Control Reverb Width When the Source Sound Is Already Wide

Start by identifying where the unwanted spread appears. Loop a passage containing both sustained sound and a gap where you can hear the tail. Listen to the source alone, the reverb alone, and then both together in the arrangement. Here, “dry” means the signal before the new reverb; it may already contain chorus, delay, or recorded ambience.

Use this decision aid to choose your first adjustment:

What you hear	First adjustment to audition	What to listen for
The source sounds right until the reverb enters	Narrow the wet return	Added depth with clearer stereo detail
Left-right source movement produces distracting reverb movement	Narrow the reverb feed	A steadier response to the moving source
The image is acceptable, but notes overlap excessively	Lower the return or shorten decay	Clearer gaps between phrases
Only the lower part of the reverb feels crowded	Apply frequency-selective processing to the return	Less congestion without losing upper-frequency space
The source already sounds indistinct with the return muted	Revisit the source processing	A clearer starting point before adding ambience

Change one variable at a time. If reducing the return level solves the problem, keep that simpler adjustment. A width change should address a spatial issue you can identify, rather than compensate automatically for every dense reverb sound.

Create a stereo auxiliary or return track and send the source to it. Set the reverb to wet-only operation; FabFilter explicitly recommends a 100% Mix setting when Pro-R 2 is used as a send effect. Put an external width processor after the reverb if you want a separate output-width adjustment. FabFilter Pro-R 2 Help — Main controls

The routing is: source → main mix, with a parallel path of source send → reverb → width processor → return fader → main mix. For this experiment, use a dedicated return. If several instruments share it, a width adjustment changes their combined reverberation too.

Begin with the width processor at its normal stereo setting. Reduce width gradually, then adjust the return fader so the comparison is reasonably similar in perceived loudness. Alternate between the original and narrower versions while the full arrangement plays. Keep the setting that lets you hear the source’s intended movement and the added space together.

A processor before the reverb changes the signal exciting it. A processor after the reverb changes the completed wet signal. Ableton’s Utility documentation confirms that its Mono switch converts incoming stereo audio to mono, while its Width control reaches mono at 0%. Its placement therefore determines which part of this routing it affects. Ableton Live 12 Manual — Utility

To compare the two approaches, duplicate your return temporarily. On the first, put the width processor before the reverb. On the second, put it after the reverb. Use identical reverb settings, audition one return at a time, and compare both with the unchanged source. Avoid playing both returns together during this test.

Choose input narrowing when you prefer how the reverb responds to a more centralized feed. Choose output narrowing when the reverb character already works and you simply want its final image more contained. A mono feed alone does not establish that a reverb’s output will be mono; inspect the reverb’s channel behavior and listen to the wet signal.

Check the manual before interpreting the number. Pro-R 2’s Stereo Width control also changes internal channel linking and cross-feeding. Its documentation describes mono at 0%, maximum cross-feeding at 50%, independent channel operation at 100%, and additional Side amplification above 100%. Those values describe that particular algorithm. FabFilter Pro-R 2 Help — Main controls

This makes a useful practical distinction: a built-in width control may change the reverb’s behavior as well as its apparent spread. An external processor after the reverb gives you another adjustment point. Audition both approaches if turning the built-in control changes a character you wanted to retain.

Do not transfer a successful percentage between different processors and assume equivalent results. Save settings with the processor name and routing position so you can reproduce the actual treatment.

If the source loses definition mainly at note onsets, audition predelay. It delays the start of the reverb relative to the original sound; FabFilter documents it as a way to increase separation between the source and tail. Width and onset separation are distinct controls. FabFilter Pro-R 2 Help — Main controls

Try a modest predelay, then listen for whether the reverb feels connected to the phrase. If it becomes a conspicuous second event, reduce it. If the problem occurs between phrases, shorten the decay or reduce the send before making further width changes.

For a source whose wide chorus movement is part of its appeal, compare a short, quiet ambience against a longer, narrower tail. Decide which supports the phrase in context. A long tail is useful only when you want to hear that continuation; a narrow tail can still occupy too much time.

Use a mid/side-capable EQ on the wet return when the problem occupies a particular frequency range. For example, Pro-R 2’s Post EQ allows individual bands to process Mid or Side information and includes low-cut, shelf, and bell shapes. This provides frequency-selective control of the finished reverb. FabFilter Pro-R 2 Help — Post EQ

As an audition, apply a gentle low shelf to the Side component and lower it a little. Bypass the band frequently. Keep the change only if the lower reverb becomes less distracting while the useful space remains. If the whole return sounds too full, compare an ordinary stereo EQ cut instead.

Treat this as a separate decision from overall width. You may prefer a relatively broad upper tail with reduced low-frequency Side content, or a uniformly narrow return. Let the passage reveal which treatment addresses the actual problem.

For an illustrative stereo synth part, try a dedicated wet return with a 0.8-second decay and 15 ms predelay. Place Ableton Utility after the reverb and compare Width settings of 100%, 60%, and 0%, adjusting return level for each comparison. These are proposed test settings, not measured results or equivalent settings for other processors.

1. Establish a return level where the space is clearly audible.
2. Compare the three widths in the full arrangement.
3. Keep the most useful width and lower the return until it supports the part.
4. Listen through a gap to assess the decay.
5. Compare a narrower input feed only if the response still follows the source’s movement in an unwanted way.
6. Remove the temporary comparison routing once you have chosen a version.

Include the mono setting even if you expect to prefer stereo. Hearing the endpoint helps you decide how much wet spread contributes to this particular part. If it crowds the center, return to a moderate width or reduce its level.

Check three states: the source alone, the wet return alone, and the combined mix. Switch monitoring to mono for each. Ableton Utility provides a dedicated Mono switch for this check. Ableton Live 12 Manual — Utility

Listen for changes in the source’s body, the audibility of the tail, and the balance against other parts. If the source changes substantially before the new reverb is added, separate that observation from what the return contributes. If the combined balance is unsatisfying, revisit wet level and width together.

Finish by playing the busiest passage and a sparse passage without touching the controls. Keep the treatment when the source’s stereo character remains clear and the reverb supplies the amount of depth you intended. That may mean a mono ambience, a moderately narrow tail, or a wider return at a quieter level.

• FabFilter Pro-R 2 Help — Main controls
• FabFilter Pro-R 2 Help — Post EQ
• Live Audio Effect Reference — Ableton Reference Manual Version 12