THD Sweep Measurement
THD SWEEP MEASUREMENT - USER GUIDE
Master the art of measuring Total Harmonic Distortion with style
| 🎵 THD SWEEP MEASUREMENT |
| Professional Acoustic Testing Made Simple |
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Install
Dowload THD measurement :
THD sweep measurement April 2026
Install model
Put the model folder : "THD computation" on model database of NVgate. (By default : C:\OROS\NVGate data\Workbook Library\User\ )
⚡ QUICK START - 30 SECONDS
| STEP | ACTION |
| 1️⃣ Launch | Launch NVgate in connected mode and load the THD computation model Double-click THD_Sweep_Measurement.exe
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| 2️⃣ Connect | Put the sweep sine on channel 4️⃣ ; put the response on channel 1️⃣ |
| 3️⃣ Start | Start the THD_Sweep_Measurement.exe and Click green ▶ START button
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| 4️⃣ Monitor | Watch 4 metrics update live , THD and frequency will also be injected on channels DC simulated of NVgate |
| 5️⃣ Stop | Click red ■ STOP button
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✅ That's it! Your first THD measurement is complete. You're now a certified acoustic engineer. (Not really, but it feels good.)
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📊 Four Metric Cards
The heart of the interface. These four numbers tell the whole story:
| 📈 THD (dB) |
📊 THD (%) |
📡 Frequency |
⚡ Fundamental |
| Harmonic distortion (log scale) | Harmonic distortion (%) | Current sweep point | Signal strength |
| +5.42 dB | 58.294 % | 1234.56 Hz | 5.0e-01 V |
🎯 UNDERSTANDING YOUR RESULTS
THD (%) - The Easy Number
What is it? Percentage of unwanted harmonics in your signal.
Think of it this way:
- THD 5% = 95% pure signal, 5% noise
- THD 20% = 80% pure signal, 20% noise
The Quality Scale:
| 🌟 1% - 5% | Excellent - Professional grade equipment |
| ✅ 5% - 15% | Good - Solid speaker performance |
| ⚠️ 15% - 30% | Acceptable - Consumer level equipment |
| ❌ > 30% | Poor - Time for an upgrade 🛠️ |
THD (dB) - The Technical Number
Same measurement as THD (%) but in decibels (logarithmic scale).
Quick Conversion Chart:
| THD % | THD dB | Quality |
| 1% | -40 dB | 🌟 Perfect |
| 3% | -30 dB | ✅ Great |
| 10% | -20 dB | ✅ Good |
| 30% | -10 dB | ⚠️ Poor |
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⚙️ CONFIGURATION
When Do I Need to Change This?
Honest answer: Almost never.
The default settings work for 95% of users. Only change if your NVGate project has:
- Different window names
- Different marker numbers
- Different DC input addresses
If you're not sure → Don't change anything. It works.
How to Access Configuration
Click on ▶ Configuration (section expands)
Important Settings
| Setting | Default | When to Change |
| Window (sweep) | Window2 | Your sweep FFT has different name |
| Window (response) | Window1 | Your response FFT has different name |
| Number of harmonics | 9 | 5 (faster), 15 (more detailed) |
How to Apply Changes
- Modify field value
- Click Apply Configuration
- Log displays "Configuration applied" ✓
- Done!
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💡 PRO TIPS
| Tip 1: Start Simple
Always use default settings first. Change things later if needed. Tip 2: Read the Log The log console tells you everything. It's your best friend. Tip 3: Use Diagnostic When something's wrong, click "Run Diagnostic". It's like magic. Tip 4: Multiple Measurements One measurement is interesting. Five measurements is scientific. Tip 5: Document Results Take a screenshot or copy the final THD values. You'll forget otherwise. |
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❓ FREQUENTLY ASKED QUESTIONS
Q: I Have only one channels. Can i take the max marker on windows 1
A: Yes, on configuration, put windows 1 for window (sweep)
Q: Is THD 5% good?
A: For a speaker? Excellent! You can be proud of that equipment. 🎉
Q: Why does THD change with frequency?
A: Because speakers aren't perfect at all frequencies. Some frequencies cause more distortion than others. That's physics being weird.
Q: Can I use this on any speaker?
A: Yes! Desktop speakers, studio monitors, subwoofers, car speakers - if it's connected to NVGate, we can measure it.
Q: How many times should I measure?
A: Once for curiosity. Three times for reliability. Ten times if you're publishing a paper.
Q: Can I export the results?
A: Yes! Copy text from the log console and paste into Excel, Word, or wherever you need it.
Q: What if my project has different settings?
A: Use the Configuration panel to adjust. It's literally made for this.
Q: Does this work over WiFi?
A: No. It only works locally (same computer or local network). WiFi would add too much latency.
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disclaimer
1) This program is delivered free of charge for NVGate V12. Support is not automatically provided on this tool.
2) For any other requests, please contact your local distributor or the OROS Customer Care department.
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| You're Ready! |
| Go measure some THD and make your speakers proud 🎵 |
THD Formulas
THD Percentage (DC1)
Failed to parse (syntax error): {\displaystyle \text{THD\%} = \frac{\sqrt{H_2^2 + H_3^2 + \cdots + H_9^2}}{H_1} \times 100 }
Where:
- = Fundamental amplitude
- = Harmonic amplitudes
Example: If H1 = 1.0 V and harmonics RMS = 0.05 V, then THD% = 5%
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THD in Decibels (DC2)
Or equivalently:
Failed to parse (syntax error): {\displaystyle \text{THD}_{\text{dB}} = 20 \log_{10}\left(\frac{\text{THD\%}}{100}\right) }
Example: THD% = 5% → THD dB = -26 dB
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Conversion Reference
| THD % | THD dB |
|---|---|
| 1% | -40 dB |
| 3% | -30 dB |
| 10% | -20 dB |
| 30% | -10 dB |
| 100% | 0 dB |
Rule: Lower dB = better (more negative = less distortion)
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Three DC Outputs
| Output | Formula | Range |
|---|---|---|
| DC1 (THD %) | Failed to parse (syntax error): {\displaystyle \text{THD\%}} | 0 - 100% |
| DC2 (THD dB) | -200 to 0 dB | |
| DC3 (Frequency) | 0 - 40000 Hz |
