OT: how can I measure THD of my amplifier if my sound card is 0,02% THD ?

[ygg-it]

Hello my sound card has a 0,02% THD+NOISE itself. (3rd harmonic)

It seems low but I have to measure my amplifier THD.

My amplifier measure is 0,022%...

Is there a way to get my amplifier THD+noise?

Can I subtract the two at each harmonic?

[Ian Finch]

Sadly, no.

Assuming you obtained .022% distortion figure using this sound card, you can only say that it is in same order or less distortion than the sound card. You need a sound card with wide bandwidth, like 24 bit 192 kHz sample rate and distortion <,= 0.001% for useful THD estimates.

If you only need to measure at 1 kHz, then a good quality 16 bit card specified to 20 kHz will do. Even older genuine Creative cards like Live or Vibra 16 were low noise and fair on THD. Generic and clone cards usually do not give original performance on noise or THD. Second hand or swap of these from old computers is sometimes fine if you have the genuine part with specs. that suit this task.

I hope this is helpful to you. Happy hunting.