THD Measurements

[nickkka]

I was wondering whether there is any particular standard test circuit used together with the op-amp to measure THD measurements.

Op-amps I am referring are audio application related such as the NE5532P, TL072 and OPA2134.

I'm using software program like the Multisim to simulate the measurements.

Any help would be appreciated.

 

[Hero999]

I think it's a bit more complicated than that, I think you need a spectrum analyser.

 

[Nigel Goodwin]

No, no need for a spectrum analyser (and there are plenty of distortion meter projects on the net) - basically you need a VERY low distortion sine wave oscillator to start with, and a VERY sharp notch filter at that frequency, followed by an AC millivoltmeter.

 

[audioguru]

The OPA2134 has distortion as low as 0.00008% which is so low that you cannot measure it.

Here is a website where very expensive equipment is used past its limit (0.0005%) for opamp distortion measurements. All the common audio opamps are measured:
**broken link removed**