Why does the permanent magnet of a speaker have to be magnetic? The coil will act when close to any metal.?
I want to build a speaker but i don't want to have to buy any magnet. I want ot use iron or something and TV yoke copper for voice coil.
This video shows; Proves, that a voice coil will function in proximity to ANY metal, not just it's own or any permanent magnet.
To generate movement of the diaphragm, the electrical signal has to move through a magnetic field, not just in proximity to metal. I don't know what "video" your talking about but this is simple physics. You sent a link to the video, which shows you holding the speaker cone (with coil attached) in the magnetic fields of three different "speakers) all of which have magnets, and for some strange reason are amazed that it produces sound. Check out the "right hand rule" in physics and you will see the principles that allowed for the development of speakers. The "magnetic field" generated by the signal flowing through the coil is not strong enough (and changes too quickly) to generate the magnetic field it needs to induce the movement that translates into real sound out of the paper cone.
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