Why a Mix Disappears in Mono
Polarity, wide bass, and short Haas delays cancel in a mono fold. What to listen for before you reach for a width knob.
A stereo mix is two channels. A mono fold adds them together. Whatever is equal in both channels gets louder. Whatever is opposite cancels and gets quieter, or vanishes. That is the whole problem. A chorus that was huge in the studio and thin on a phone is usually this, not a bad master.
Paraflex Mono Optimizer is a VST3 plugin, and an Audio Unit on macOS, for that fold. The guide is the first check on a mix you know is wide. This note is why the song left in the first place, so the knobs have somewhere to land.
Three ordinary causes
A polarity flip. One side, or one band, is inverted. Sum it and that band leaves. It is common after a wide sample, a mid-side move taken too far, or a layer that was flipped to "make space."
A very wide low end. Bass that lives in the sides has nowhere to go when a club, a phone, or a broadcast fold adds the channels. The fold map in Mono Optimizer shows this as a bright band at the bottom. That is the dangerous one, because bass that cancels is bass the system does not play.
A short Haas delay. A few milliseconds between left and right reads as width in stereo and as a comb when the channels are summed. Haas repair is the specific switch for that case. Leave it off unless you hear that problem. It is not a general widener, and it is not the first knob.
Width that was made by any of these three does not come back when you turn a width knob down. The sound is still opposite. It is only quieter. Rescue is the process that folds cancelled energy back. Image is how much of the original picture you keep around that repair.
What to listen to
Put the plugin last on the bus that has to survive mono. Leave plugin delay compensation on. The plugin reports its delay.
- Leave Rescue and Image where they start. Both start fully up. Limit stays on. Haas repair stays off.
- Click Mono. You hear the fold.
- Click Lost. You hear only what the fold would discard. This can be quiet. If Lost is almost silent, there is little to rescue.
- Click Stereo again and decide whether the repair damaged a width you wanted.
Loss, Saved, and Fixing are there so you do not guess. A healthy wide mix can show a small Loss. A flipped side, a very wide low end, or a Haas delay can show a deep Loss. You do not need Loss at exactly zero. You need the mono speaker to contain the vocal, the bass, and the lead lines.
Rescue at zero is no repair. The Loss number is still honest about the input. Do not judge the plugin with Rescue down and conclude the mix is fine.
Where it does not belong
Leave it off a source that is already mono. There is nothing to rescue, and the displays sit near zero loss. It is also the wrong tool for a creative stereo effect. Lens and Duality make width and colour. Mono Optimizer is the last plugin on the bus that has to survive a phone, a club system, or a broadcast fold.
This release is VST3 on Windows, and VST3 and Audio Unit on macOS. The current price is on the Mono Optimizer page.
Keep exploring
See the tools behind these workflows.