Rescue and Image on Mono Optimizer
Rescue brings cancelled energy back. Image decides how much stereo width stays around that repair.
Rescue and Image answer two different questions. Rescue is how much of the stereo energy that would cancel in mono is folded back. Image is how much of the original width is kept around the parts that were rescued. Both start at full.
Mono Optimizer is a VST3 plugin, and an Audio Unit on macOS. Put it last on the bus that has to survive a phone, a club, or a broadcast fold. The guide is the first check. This note is the trade between the two knobs.
Rescue
Full is the normal setting. The processor does the rescue it is willing to do on this material.
Lower leaves more of the cancellation alone. Use that when the Lost listen is mostly reverb and sparkle you are happy to lose in mono, and you want the repair to stay subtle in stereo.
Zero is no rescue. The fold behaves like the untreated mix. Loss still reads the problem. Rescue is an amount, not a bypass of the whole plugin. Optimizer bypass is the fair before-and-after, at the same delay.
Rescue is not a width knob. If you lower Rescue and the mono vocal gets thinner again, the cancellation is returning. Raise Rescue.
Image
Full keeps as much of the stereo picture as the rescue allows. Material that was strongly inverted still folds back toward a solid mono sum, and a little width can remain where it is safe to keep.
Lower pulls the rescued sound toward the centre. Zero is the most centred result this processor makes.
Set Rescue for how much of the missing mono comes back. Set Image for how wide the stereo still feels after that. Check Stereo, then Mono, then Lost. Stereo tells you whether you damaged a width. Mono tells you whether the song is still there. Lost tells you what you are still willing to abandon.
Three factory points on the same trade
| Preset | The trade |
|---|---|
| Club Safe | Full rescue, Image a little under full. A club fold that does not throw the width away |
| Wide Keep | Rescue eased off, Image full. More of the original picture, less intervention |
| Broadcast Mono | Full rescue, Image well toward the centre, Limit on. A fold that is meant to be mono-first |
Haas Fix is a different case: Rescue high and Haas repair on, for width that came from a short delay. Leave Haas repair off unless that is the problem you heard. The fold map tells you where the loss lives. A bright band at the bottom is low end. A bright band in the highs is often a stereo reverb or a widener on cymbals. You may rescue that less.
A check that does not lie to you
Leave Limit on while you learn the knobs. The plugin reports its delay. Leave plugin delay compensation on.
Watch Loss, Saved, and Fixing. If Loss was badly negative and Saved is clearly positive while Rescue is up, the processor is doing the job. You do not need to pin the correlation marker at the far right. A record with real stereo will sit somewhere positive and still have width. Image at full is allowed to leave some of that width in place. A total collapse toward dual-mono is what Image at zero is for.
Keep exploring
See the tools behind these workflows.