ARTA single channel frequency response measurement problem

[wutzke]

Hi, can anybody explain how to measure the frequency response in single channel mode with an external signal using ARTA?

I am trying to measure the frequency response of a music player. Here is what I did:

1. Saved the 'PN pink' signal as a wav file and copied it to the music player.
2. Connected the music player output to the sound card input.
3. Started the playback of the test signal.
4. Started the recording in single channel frequency response mode in ARTA.

Here is the result:

An externally hosted image should be here but it was not working when we last tested it.

The blue line is the response of the sound card in loop-back setup. The green line is the response of the music player. Why does the result look so strange? What I am doing wrong?

I have successfully measured the THD+N, see below, so the setup and the DUT should be ok.

An externally hosted image should be here but it was not working when we last tested it.

Best regards

 

[CharlieLaub]

I wonder if you have more than one signal being recorded at the same time, and they are interfering and causing the strange pattern. Check your mixer/input settings to make sure that only one is enabled at a time.