Vectorscope

Vectorscope

Vectorscope plots the relationship between the left and right channels. It helps reveal stereo width, channel balance, polarity, phase risk, and frequency-dependent stereo structure.

It does not label a stereo image as automatically good or bad. Interpret its pattern together with the correlation display, level meters, and what you hear.

Display modes

Prism provides three projections, with folded variants where applicable.

Mode	Shape and emphasis	Useful for
XY (L/R)	Direct left-versus-right square projection	Channel peaks, balance, polarity, and familiar Lissajous patterns
Polar	Radial stereo projection	Stereo angle and width in a compact circular view
M/S Linear	Mid/Side projection with a diamond reference	Direct comparison of common and difference content

Folded Polar and M/S modes rotate negative-Mid samples into the upper half of the display. They do not throw those samples away. Bipolar keeps the complete positive and negative projection.

XY is the default mode.

Reading common patterns

• A narrow trace near the mono axis indicates strong similarity between left and right.
• A wider cloud indicates more difference information and perceived width.
• A strong horizontal or Side-oriented pattern can indicate polarity or mono-compatibility risk.
• A pattern leaning toward one channel indicates left/right imbalance.
• A circular or diffuse pattern can come from decorrelation, ambience, modulation, or noise.

The outside of the left/right reference guide is subtly shaded in applicable modes. Points there are instantaneously Side-dominant. Brief excursions are normal; sustained behavior deserves a correlation and mono check.

References differ by projection

The XY square and M/S diamond use exact per-channel sample-peak references. Reaching a guide therefore has a direct peak relationship in those projections.

Polar mode uses amplitude-compressed radial scaling so both quiet and loud structure remain visible. Its circle is a radial visual reference, not an exact per-channel dBFS boundary. Do not infer clipping from the Polar circle alone.

Zoom

Zoom ranges from -12 to +24 dB and defaults to 0 dB.

• Positive zoom magnifies quieter structure.
• Negative zoom fits louder excursions into less display area.
• The labeled reference changes with zoom; at +12 dB zoom, for example, the visible reference corresponds to -12 dBFS.

Zoom is display-only. It does not amplify, attenuate, or otherwise process the signal.

RGB multiband

Enable RGB to color different frequency regions separately. This helps show whether stereo width or imbalance is concentrated in the lows, mids, or highs.

RGB is off by default. A single-color trace is usually clearer for overall geometry; turn RGB on when the frequency distribution of that geometry matters.

Persistence and line width

Persistence retains earlier samples briefly, from 0 to 0.50; the default is 0.10. Increase it to expose a stable envelope around intermittent points. Reduce it for the most immediate picture.

Line Width ranges from 0.5 to 4 px and defaults to 1.5 px. It changes presentation only.

The Grid toggle shows or hides the projection's guides and is on by default.

Use correlation as a second opinion

The VU and Loudness modules include a correlation bar. Values toward +1 mean the channels are similar; values near 0 indicate little linear relationship; negative values indicate opposing behavior that may cancel in mono.

Correlation summarizes a time period while Vectorscope shows detailed instantaneous geometry. Use both before deciding that a wide pattern is unsafe.

Practical checks

• Compare the pattern during the loudest and quietest sections; one snapshot may not represent the program.
• Toggle RGB when the low end appears much wider than expected.
• Use XY or M/S for exact peak-reference interpretation; use Polar for a compact view of angle and width.
• Check the mix in mono when correlation stays negative or Side-dominant points persist.
• Use Level and Loudness Meters to distinguish phase behavior from simple level imbalance.