A few days ago I bought a new desktop speaker from my last month saving. I chose Simbadda CST 6300N because the price fair enough and sound quality not bad. Then after going home and install a brand new Simbadda CST 6300N, I felt strange when I heard the music without play any music (feels spooky huh?). Then I was realized that those musics come from 101JakFM radio broadcast. And the conclusion is my speaker getting that radio signal noise or usually called as radio frequency interference. And Wikipedia says:
Electromagnetic interference (EMI, also called radio-frequency interference or RFI when in radio frequency) is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.
I’m not really good at electronics stuff. And with that keyword, I googled and found that to get rid that noise I should use Ferrite Suppression Core or Ferrite beads or also called as Ferrite Clamp. And here some short fact about Ferrite Suppression Core:
This Ferrite suppression core is packaged in a nylon case ready to clamp on a single cable or several cables connecting to electronic equipment. The purpose of the core is to attenuate conducted Electro-Magnetic Interference (EMI) in the 25 MHz to 200 MHz range. Increasing the number of cable turns through the core increases the impedance of the core. A higher impedance results in greater EMI attenuation. Placing more than one core on a cable increases the impedance at a slower rate than adding turns to one core. The impedance for multiple cores is equal to the sum of each core’s impedance. For a given application, start with a single core using 2 turns. Add additional turns or additional cores as necessary.
Then next day. I went to Glodok. And unfortunately, that day was Sunday, mostly the electronics shops closed. But finally I managed to get a shop opened on LTC Glodok (The shop direction: from the main entrance, go up to the second floor, and the shop is on the left, 10 meters from the escalator). The Ferrite Clamp cost about 12000 IDR each. Then quickly I went home to try it. And it works! These Ferrite Clamp reduces that noise by 98%. And here an instruction how I installed the Ferrite Clamp:
Here the results: