Building speakers, induction and induced current

[Porter22]

i made a speaker from a cup, a coil of wire and a magnet. I hooked up both of the ends of the wire to a headphone jack and it works. Albeit very low sound, but it works.

Can you point me in the direction of some equations that will show me the most influential factors on how to make it louder? I've been also looking at impedance and their effect at high and low frequencies. I know my differential equations so lay it on me if you can.

I would like to know more about Φ(flux), too.
How can I measure the strength of a magnet?

I'm playing around with creating small ac current by spinning a motor with a magnet on it inside a coil... pretty simple.

 

[anorlunda]

The search term " DIY speakers" gives lots of hits, both web and YouTube. I bet you can get more specific help from those sources.

 

[Inventive]

You might find the information in this article helpful
http://www.ajdesigner.com/phpsubwoofervented/box_volume_equation.php

 

[Andy SV]

You don't need complicated equations for your stated goal
more powerful less massive coil and cone
more massive and more powerful magnet