Hello,
I have a VLF receiver with a audio amplifier that can make small earphones sound like small bluetooth speakers, they are very loud. However, If I take a signal from TV/Radio plug from the wall and I record from it, Audacity generates a blue steady line that sometimes almost goes to the top of the audiotrack. I have tried to equalize to remove the sound or noise removal/notch but they don’t help. I don’t know if Audacity can go below -1024db but if so, It still has the 50Hz buzz, or the other tools just make it sound like bass or very deep 50hz rather than very loud and crisp 50Hz. Is there a filter that it won’t record below 100Hz or a permanent frequency deletion? I would connect the antenna to gutter but I believe it still would pick some of the 50Hz buzz so I have to find a way to remove it.
Cheers!
Could you provide (i.e. attach) a sample, a few seconds long, as wave file?
Audacity generates a blue steady line that sometimes almost goes to the top of the audiotrack.
That’s not sound. Chances are good that’s DC offset. There’s battery voltage leaking into the sound. You can’t hear it but it can cause some serious sound damage later.
Effect > Normalize: Remove DC > OK.
Does the blue line settle down to the middle of the wave window?
That can be a badly damaged analog to digital converter. “Normal” DC offset damage is much smaller. This is a bad edit caused by DC offset in a crappy soundcard.
Koz
There’s no show there at all. That’s just trash.
If I take a signal from TV/Radio plug from the wall and I record from it
Say that again and use a lot more different words. “I connected an audio cable from the VLF receiver headphone socket to the Mic-In of my Lenovo laptop.”
Koz
That’s just a short circuit.
Close your fingers around a line-in cable and you’ll get something similar.
Either the cables or the adapters are faulty.