I have more than 10 XLR microphone cables from different manufacturers (some of them quite cheap, some of them more expensive), and as I often do recordings (with condenser microphones) of music / audio samples that have a low SNR (signal to noise ratio), I'd like to do my best to pick the right audio microphone cables.
How to measure the quality of such cables, and have a non-subjective quantitative measure of its quality?
Here is the workflow I'm using for now:
- Generate a 10-second long 20 Hz - 20kHz frequency sweep (something like this)
- Play it with Soundcard 1 (that is reliable)
- Plug the XLR audio output of Soundcard 1 to XLR audio input of Soundcard 2
- Record the sound with Soundcard 2
- Analyse the spectrogram of the recorded signal
I get such results:
It looks good, but:
Can I be sure that an XLR that is ok to transmit audio signal from Soundcard 1 to Soundcard 2 at "line level" will also be good for microphone signals?
I don't want to involve the microphone in my workflow because everything would be dependent of the ambient noise in the room where I do the tests, and then it won't be very reliable (I tried, and even quiet footsteps from the guy on the floor above changed the low frequency charts!)
Note: I sent the audio swipe at various levels to Soundcard 1: -12 dBfs, -24 dBfs, ..., -80 dBfs, but what would be an audio level/voltage that mimics "microphone signals"?