Total Harmonic Distortion tests and results, part 2 – 20 KHz performance

Total Harmonic Distortion performance at 20 KHz.

Next step is to test performance of all stages at higher frequencies.  All tests are performed in the same manner as in previous testing.  Inputs of all 4 stages are connected together and transfer function of every stage is modified to have Gain=1 with corresponding loads and at 20 KHz. Read more

Total Harmonic Distortion tests and results

Test setup for THD measurements.

I will use my Total Harmonic Analyzer for LTSPICE to perform these tests. Control script is slightly modified, to decrease test (simulation) time. It is possible to do so, because all schematics are settling fast and we are not looking into very small THD numbers. Signal amplitudes are also of moderate values. Read more

AC performance, part 2. Input capacitance modulation. Load influence.

Modulation of Input Capacitance.

Changing offset causes some changes in the frequency response. While AC analysis is small signal analysis, offset change will show some differences in big signal performance. One part of this change is modulation of Ccb capacitance. Read more

AC performance of 4 output stages.

AC small signal gain, 8 Ohm load.

Overall gain for all 4 stages was evaluated on the following plots.

We will try to use similar colors for all comparison testing. Read more

In the search of “Holy Grail” of output stages, evaluating performance of Power Amplifier output stages for High-End applications

Performance of output stage plays a significant role in overall performance of audio power amplifier and, together with VAS output stage, may be considered to be the major source of distortions. Read more