SLAAED0 March   2024 TAS2764 , TAS2780 , TAS2781

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Measurement Methodology
  6. 3 Introduction to Noise-gate and Pop in Class-D Amplifiers
  7. 4 Causes of Pop in TAS27xx family of Class-D Amplifiers
  8. 5 Click and Pop Using TAS27xx
  9. 6 Click and Pop Measurement Technique Using AP v6.0. 2
    1. 6.1  Measurement Setup
    2. 6.2  Filter Settings
    3. 6.3  Data Capture Settings
    4. 6.4  Auto Range Settings for Pop Measurement
    5. 6.5  ASI or I2S Configurations for Pop Measurement
    6. 6.6  APx Sound Level Meter Utility
    7. 6.7  Data Acquisition
    8. 6.8  Interpreting Click and Pop Waveforms
    9. 6.9  Post Processing of AP Waveforms
    10. 6.10 A-Weighted Click and Pop Numbers
    11. 6.11 Exporting the A-Weighted Numbers
  10. 7 Noise-Gate Pop and Measurement Technique Using APx
  11. 8 Configuring TAS2764 for Improved Click and Pop Noise Performance
    1. 8.1 Explanation
  12. 9 Summary
  13. 10References

7 Noise-Gate Pop and Measurement Technique Using APx

To measure the noise gate (NG) power up and power down pop of the device, a repetitive audio input stimulus slightly higher than the noise gate threshold is given to excite the device and exit NG (wake up). This is followed by a long period of silence greater than the NG hysteresis timer to allow the device to enter NG and shutdown. By default the NG threshold is at -120 dBFs in TA27xx amplifier product family.

An input stimulus such as this can be generated using a low frequency, low amplitude sine wave such as 1Hz with -119dBFs. This makes sure that the device exits from noise gate at the peak audio sample and enters into noise gate since the amplitude remains well below noise gate for long durations (> NG hysteresis of 5ms).

GUID-20231109-SS0I-V6H0-KSBB-HBWD5TCPWXMP-low.png Figure 7-1 Sample Generator Excitation for Capturing Noise Gate Pop

Using Audacity or other software as well as excitation.wav waveform file can be generated and imported into AP, and played in the measurement recorder. If an external audio.wav file is used, the file has to be fed as input in APx as shown in Figure 7-2.

GUID-20231109-SS0I-JK9S-TQ2B-N3QCFCFL11HH-low.png Figure 7-2 APx Configuration for Importing External .wav Excitation

All other filter settings, I2S configuration settings, and recorder sample rate settings remain the same.