Why is 20HZ audible on PC?

[goldyrathore]

Hi,

I just wanted to check XMAX of my woofer. I though 20 HZ was not audible so the moment I hear harmonics of 20HZ I could get a rough idea of the XMAX of the driver.
I ran CoolEdit 2000 (demo) and generated a 20 HZ signal (sine). The sound card output was connected to an AMP and woofer driven directly by the amp. I was surprised to hear a loud audible sound. As far as I know 20HZ is not audible. Whats going wrong. I know that the soundcard and amp will not perform quite well at 20 Hz but I still cannot believe that the sound is so distorted.


Thanks in advance.
Goldy

 

[AudioFreak]

20Hz is audible to alot of people. Try doing a sweep from 20HZ to 50Hz and have a listen, that should give you some idea of how much is harmonics and how much is fundamental.

 

[pinkmouse]

20Hz is audible to alot of people. Try doing a sweep from 20HZ to 50Hz and have a listen, that should give you some idea of how much is harmonics and how much is fundamental.

If you have a cheap computer mic you could use it to check for distortion using your sine wave signal and a downloaded FFT program,( there are many out there, some as VST plugins you could use with cooledit).

Plug the mic into your soundcard and play the tone through your driver and look for other peaks on the fft display apart from the fundamental at 20 Hz. If you then just do the same with the signal level output connected directly to the input of your soundcard you can see how much distortion is due to the driver, and how much to the souncard.

You will need to do this outside, or with the mic very close to the speaker to avoid room effects.