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Stereo Alignment Monitor

Stereo Alignment Monitor

Overview

A comprehensive tool for analyzing the alignment and consistency between L/R channels.
It monitors L/R balance, frequency response match, center focus, and phase issues in real-time, providing both quantitative and visual evaluations. Extremely useful for verifying speaker setups and measuring channel imbalances in audio equipment.

Operation

Start and Stop Analysis

  • Start/Stop Button: Toggles the analysis on and off.

Parameter Settings

  • Smoothing: Adjusts the amount of temporal smoothing applied to the plots and analysis metrics. Higher values result in slower, more stable readings, making it easier to evaluate consistent trends.

Reading the Plots

L/R Difference FFT (Tone Color Shift)

Displays the spectra of both L and R channels and highlights the "difference" between them.

  • Green line: Left channel spectrum.
  • Yellow line: Right channel spectrum.
  • Shaded area: Indicates the level difference (tonal variance) between channels. When both channels match perfectly, the shaded area disappears.

Band-specific Phase Correlation

Displays the phase correlation coefficient (-1.0 to 1.0) across the frequency range.

  • 1.0: Perfectly in-phase (monaural signal).
  • 0: Uncorrelated (fully independent channels).
  • -1.0: Perfectly out-of-phase (phase inversion). Allows you to visually identify which frequency bands are experiencing phase alignment issues.

Analysis Metrics and Judgments

The panel on the right provides judgments based on four key metrics:

Metric Description Judgment Thresholds
L/R Balance Displays the difference in total energy between L and R in dB. < ±0.5dB: Excellent / < ±3.0dB: Good
Freq Match Displays the correlation of frequency responses between L and R as a percentage. > 95%: Professional / > 80%: Good
Center Focus Displays the "center localization (M/S ratio)" of the overall signal. > 85%: Mono / > 50%: Wide
Phase Issues Displays the percentage of energy with negative correlation (out-of-phase components). < 1%: Safe / < 10%: Minor

M/S Ratio Bar

A visual bar representing the ratio between center localization (Mid) and spatial components (Side).

  • Towards 100% Mid (Mono): The signal is concentrated in the center.
  • Towards 100% Side (Wide): The signal is spread widely across the stereo field.
  • Around Center: Indicates a natural stereo image.