Using my new QA401/QA451 to measure THD+N vs Power for several amplifiers. The results have all shown much lower power than expected for the rated amplifier’s output. Have measured 2 Class D and 2 Class AB amplifiers. The results are relatively proportional and curves rise as expected. For example, a 500 watt Hypex NC502MP is only reporting less than 90 watts output at 1%THD (4 ohm load).
I measured the single-ended outputs of the QA401 at .5 volts (0 db), so increased the gain to maximum (6 db). Still does not drive the amp to anywhere close to rated power. Also am aware that QA451 can only deal with short power bursts. Is the QA451 the reason for apparently low output?