Thanks! I found the post and I hate to admit it, but I have never used any of the Measurements Buttons. I just select what I want with the Add measurements window. So I set it up to go from 20Hz to 40kHz with the THD measurement button, set the XLOG to the same and then ran the automated test from 20-40kHz with the THD+N box unchecked and (imaginary drum roll) it gave me the range I wanted- here is the plot:
It is for a different amp, but looks fine. I also plotted the THD/SNR at 20kHz and it gave a power reading that was reasonable (forgot to see what it said the THD was though ). So maybe not setting the range using the THD measurement button was the problem ???
Yes. The thd button menu sets the range in the input signal over which distortion is measured and the automated test menu sets the range over which the generator will generate a signal. At least that’s the way I think it works!
Glad you got the results you needed.
It looks pretty darn good compared to the <0.01% spec! I also measured the THD at 20kHz under the same conditions and got this, which compares very close to the plot above. I found that I had to extend to 45kHz to get the %THD to be non-zero :
I would love to. I was planning on showing them in an upcoming video I was planning to do for my (small) youtube channel when I talk about using the QA402 (don’t laugh too hard ). They are not “pretty” and I learned from making the 8ohm loads when I made my 4ohm loads, but I can “shoot” the load part and use it later and just post it to my cloud drive for now. Later today or tomorrow most likely.
Forgive me if I’m jumping in without being fully informed here. I’m new with this software and have not fully digested all of this post. But I just wanted to note that I have run into issues with this test when averaging is turned on in the main window of the app.
). So maybe not setting the range using the THD measurement button was the problem ???
Will see how my measurements go later today using a 4ohm load- I will pay attention to the “manual” measurement THD at 20k this time…
). They are not “pretty” and I learned from making the 8ohm loads when I made my 4ohm loads, but I can “shoot” the load part and use it later and just post it to my cloud drive for now. Later today or tomorrow most likely.