Why does widening do nothing on some files?

Because only the difference between the two channels is scaled. If a recording has identical left and right content, as a mono file doubled to stereo does, there is no side component and no width to change. Hard-panned and heavily stereo material responds far more.

What does the side energy figure measure?

How much of the total energy sits in the difference between the channels rather than in what they share. It scales with the square of the width factor, so the number changes quickly as the width moves, and it is a more honest measure of widening than an impression that the sound got bigger.

Why is there a peak warning?

Because the side component is added to one channel and subtracted from the other, so on material whose sides are partly inverted the two can sum to more than full scale. The warning reports it rather than hiding it, and bringing the level down afterwards is a matter for the amplifier.

Does widening hurt mono compatibility?

It can. The more the sides are exaggerated, the more a mono fold-down loses, because the fold averages the two channels and anything that differs between them partly cancels. If a mix has to survive mono playback, check it with the stereo to mono converter after widening.

What width should I use?

A hundred percent is exact identity, so anything above it is a deliberate exaggeration. Around a hundred and twenty to a hundred and forty opens a narrow mix without sounding unnatural; beyond a hundred and eighty the sides tend to dominate and the effect becomes obvious rather than flattering.

Stereo Widener

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Stereo Widener changes how wide a stereo recording sounds by scaling the difference between its two channels. The centre stays put while the sides move further apart or closer together.

What is Stereo Widener?

Drop a stereo file, set the width, and process; the panel reports the side channel's share of the total energy before and after, and warns if the output peak went past full scale.

The control and the readout:

A width from nothing to two hundred percent, in five percent steps, defaulting to a hundred and forty.
Five presets named for what they do: mono at nothing, narrow at seventy, normal at a hundred, wide at a hundred and forty, and ultra at a hundred and eighty.
A footer giving the side channel's percentage of the total energy before and after processing, and the output peak.
A channel requirement: the tool needs two channels, and a mono file is refused rather than silently doubled.

The arithmetic is a change of basis. A stereo signal can be described by its mid component, which is the average of the two channels and carries everything common to both sides, and its side component, which is half their difference and carries only what differs. Widening multiplies the side component by the chosen factor and rebuilds the two channels from the scaled pair, so at a hundred percent the operation is an exact identity, at nothing it collapses to mono, and above a hundred it exaggerates whatever differs between the sides. Expressing the result as the side channel's share of the total energy is what makes the readout honest: that share scales with the square of the width factor, so a hundred and forty percent width multiplies the side energy by nearly two, and the figure shows the change directly rather than merely restating the setting. There is one consequence worth understanding before using it. Content that is the same in both channels has no side component at all, so widening cannot make it wider; only what already differs is affected, which is why a hard-panned mix opens up dramatically while a mono-compatible one barely changes. And because the side component is added to the mid in one channel and subtracted in the other, material with an inverted relationship between the sides can grow beyond full scale, which the tool reports as a peak warning rather than allowing it to pass silently. Bringing the level back afterwards is a job for the amplifier.

Where it does not help:

Mono or near-mono material gains almost nothing, since there is no side content to scale.
Out-of-phase content can exceed full scale at high widths, which is reported rather than prevented.
No frequency-dependent widening, so the whole spectrum moves together.
No control over the width over time.
No monitoring of mono compatibility, which is worth checking separately.
Output is sixteen bit WAV.

Use it to open up a mix that was recorded narrow, to push a doubled part to the edges of the image, or to check how a mix behaves when its sides are exaggerated. When the aim is to create width where there was none by adding a copy rather than by scaling a difference, the chorus and the mono to stereo converter are the tools for that, and when the mid and side components need to be manipulated separately, the mid side encoder is the direct route.

How to use Stereo Widener

Drop a stereo file onto the panel; a mono file is refused by design.
Set the width, starting at a hundred percent to confirm the output matches the input.
Read the side energy figures to see how much the image actually changed.
Check the peak warning and bring the level down with the amplifier if it appears.

When to use Stereo Widener vs related tools

Stereo Widener is the tool for changing the width of an image that already has side content, which is what makes it different from adding a second voice. Mid-Side Encoder exposes the mid and side components for separate treatment, and Mono-to-Stereo Converter creates a stereo file from mono without adding width at all. When the movement rather than the width is the goal, Chorus Effect and 8D Audio Converter add it by other means.

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