Very Strange Frequency issue

1

Hi All…
I am working on a new design that requires high frequency analytics. So I need to measure things above 80 Khz. So when I go up in frequency Im getting very weird information on the display. I am simply using a loopback XLR with Differential outs to Differential inputs. Cable checks out perfectly as far as connections go. When I go above 20 K the gain and level goes crazy. Please see Fig 1 and Fig 2. Fig 1 shows frequency at 16.7K note the gain is very close to zero dB of gain. Now in Fig 2 I simply went to 24K and the gain shows 149 dB! WTF!!! I have tried everything. Reinstalling the software and making sure Im not doing something dumb. So perhaps someone here can explain this odd occurrence.
Thanks
Fig 1

IMG_7794.HEIC
IMG_7794.HEIC4032×3024 3.65 MB

Fig 2

IMG_7795.HEIC
IMG_7795.HEIC4032×3024 3.63 MB

2

If you don’t change the measurement bandwidth, that will happen.

Obviously, the sample rate is at 192k and your measurement ‘stop’ frequency needs to be also set to ~80kHz.

image
image302×359 5.03 KB

(right click the THD button to access the options)

We all made that rookie error when first measuring- I know I did. :slight_smile: