THD measurement

geadinc

I've been asked to optimize a compressor/limiter for a client and I need to check the THD response and minimize it. It's not clear to me that SignalScope Pro would work for me or not. Could someone tell me if it does a reasonable job of measuring THD between input and output of a device?

benfaber

SignalScope Pro's FFT Analyzer tool is capable of computing THD with up to 15 harmonics.
In order to get good results, you'll need to use a test signal that's at a frequency that matches one of the frequency bins in the FFT. This is fairly simple if you use SignalScope Pro's built-in signal generator and use the same audio device for both output and input in your measurements.

geadinc

Cool, thanks! I'll be using a Presonus Firestudio Mobile to give me the XLR in and out.

brianf7408

Am I correct in assuming that the number of spectral lines is equivalent to the number of bins?

benfaber

Am I correct in assuming that the number of spectral lines is equivalent to the number of bins?

Yes. Each line represents one bin.

Abba_Hong

Sometimes iOS resets the 'Microphone' permissions after an update. It’s worth double-checking in Settings > Privacy > Microphone to make sure the app still has access. Also, if you’re using a USB-C hub, sometimes the order of connection matters - try plugging the interface into the hub first, then the hub into the iPad/iPhone.