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🔊 Audio Analysis Tools

🎯 Herramientas Esenciales

╔═══════════════════════════════════════════════════════════════════╗ ║ Tool │ Qué mide │ Precio │ Uso ║ ╠════════════════╪════════════════════════╪═════════╪══════════════╣ ║ PluginDoctor │ THD, freq response │ ~$100 │ Validation ║ ║ SPAN │ Spectrum analyzer │ Free │ Visual check ║ ║ Oscilloscope │ Waveform │ Free │ Artifacts ║ ║ REW │ Room measurement │ Free │ Reverb test ║ ╚═══════════════════════════════════════════════════════════════════╝

📊 PluginDoctor Workflow

  1. Generate test tones (sine, sweep)
  2. Feed through plugin
  3. Analyze output
  4. Compare to spec:
  5. THD+N < 0.001%
  6. Frequency response ±0.5 dB
  7. Phase response linear

Example Test Procedure

1. Load plugin in DAW
2. Route PluginDoctor generator → Plugin → PluginDoctor analyzer
3. Run sine sweep 20Hz-20kHz
4. Check results:
   ✓ Flat frequency response
   ✓ Low THD
   ✓ No aliasing artifacts

🎨 Visual Tools

SPAN (Spectrum Analyzer)

  • Real-time FFT display
  • Peak hold mode
  • Compare A/B
  • Use case: Quick visual check of frequency content
Download: https://www.voxengo.com/product/span/
Free, cross-platform
Perfect for debugging filter responses

Oszillos (Oscilloscope)

  • Waveform visualization
  • Detect clipping
  • Phase correlation meter
  • Use case: Catch waveform distortion

MeldaProduction MAnalyzer

  • Comprehensive analysis suite
  • Sonogram view
  • Correlation meter
  • Free version available

🔍 THD+N Measurement

What it measures: Total Harmonic Distortion + Noise Target values: - Clean plugin: < 0.001% (-100 dB) - Vintage emulation: 0.01-0.1% (intentional) - Saturation: 1-10% (designed distortion)

How to test: 1. Generate 1kHz sine wave 2. Process through plugin 3. Remove fundamental (1kHz) 4. Measure remaining energy = THD+N

📈 Frequency Response Testing

Sweep test: 

1. Generate log sweep 20Hz-20kHz
2. Process through plugin
3. Deconvolve to get impulse response
4. FFT → frequency response
5. Compare to theoretical response

Acceptance criteria: - EQ: ±0.5 dB deviation from target - Filter: Rolloff slope matches design - Transparent: ±0.1 dB 20Hz-20kHz

🎚️ Dynamic Range Testing

Signal-to-Noise Ratio (SNR): 

1. Process 0dBFS sine wave
2. Process silence (no input)
3. SNR = Signal level / Noise floor
4. Target: > 96 dB (16-bit) or > 144 dB (24-bit)

⚡ Latency Measurement

Ping test: 1. Send impulse through plugin 2. Measure output delay 3. Compare reported latency to actual

Tools: - PluginDoctor: Automatic latency detection - Manual: Align impulse in DAW

🔊 Phase Response

Linear phase: All frequencies delayed equally Minimum phase: Natural, analog-like Non-linear: Can cause artifacts

Test: - Sweep test → measure phase - Check for discontinuities - Verify mono compatibility

📋 Test Checklist

  • THD+N < target threshold
  • Frequency response within ±0.5 dB
  • Phase response appropriate for plugin type
  • No aliasing artifacts
  • No DC offset
  • Proper gain staging (no clipping)
  • Latency matches reported value
  • Mono/stereo compatibility
  • Bypassed state truly bypasses

🛠️ DIY Testing Tools

If you can't afford commercial tools:

Free alternatives: - Room EQ Wizard (REW) - Full suite - Audacity - Spectrum analysis - Sonic Visualiser - Research-grade analysis - Python + librosa - Custom analysis scripts

📝 Documentation Template

# Plugin Audio Test Report

**Plugin:** MyCompressor v1.0
**Date:** 2025-01-03
**Tester:** Your Name

## Test Results

### THD+N @ 1kHz
- Input: 0dBFS sine
- Output THD+N: 0.0008% ✓
- Target: < 0.001% ✓

### Frequency Response
- 20Hz-20kHz sweep
- Deviation: ±0.3 dB ✓
- Target: ±0.5 dB ✓

### Latency
- Reported: 64 samples
- Measured: 64 samples ✓

## Verdict: PASS ✓