HR Noise 2: Who Is the Guy?
Last Updated on May 14, 2020
"Hello the guy..."
"Bye-bye like that..."
However, he is not guilty!
...
Still high pitch noise with Les Paul SL, DIY preamp, and UCA222.
So I doubt the distance between my Les Paul LS and the unshielded DIY preamp under making. Seems electromagnetic resonance with no sound.
On the ukulele recording with the DIY piezo, there was no high pitch noise...
Seems coil whine.
Hypothesis: The LC tank circuit is made of the pickups of the guitar and the capacitor of the preamp. The tank is feedbacked through GND and so.
Counterplan: Hide magnets in any trans, power supply, and speaker for regular things of pickups.
Or here comes the piezo (CC tank) world.
So unplugged the guitar and check spectrum. The same noise exists. The hypothesis is broken down. It's preamp's inner LC tank. It's time to solder!
And unplugged the preamp. UGREEN's MIC In is only with a 1m cable. Amazingly, the noise still exists! Then unplugged the cable from the MIC In. Here comes the silence!
The reason is 1m cable to connect between the preamp and the MIC In!
So I made loops by the 1m cable and the high pitch noise is gone!
Hmm. Try a ferrite bead.
Double check, then the loops of the cable don't erase the noise!
...
So I now doubt PC noise. The spectrum of no connection still shows high pitch noise.
Let's buzz talk. Both UGREEN and UCA222 have the noise. Sometimes it disappears. Hmm, USB noise caused by digital data packets, or switching noise of the power supply for the PC?
Its noise level is lowest with no connection, and higher with further connections. Connections make its amplification. High gain and level of the preamp seems to amplify the guy.
Does high gain/level recording still need analogue tools such as tape cassettes?
Coil whine of the power supply? Try battery power.
Acoustic noise of any ceramic capacitor in PC? Change PC, e.g., from RasPi3 to RasPiZero.
WiFi radio wave? Turn off as possible.
Outlet/multiplug? Change anyway.