speaker design

For a class I'm taking we have to design a working speaker, and we are allowed to use only the basket and magnet from an existing speaker.  Everything else, diaphram, spider, surround, ect must me made.  My question is what materials would you guys suggest for making these parts.  Any help and suggestions are greatly appreciated.

Also, we are probably making a 10" and a much smaller speaker--something like a 5" because it will get hooked up to a small 12 watt stereo (boombox). Although, we can probably hook the ten up to my car amp if needed.

Thanks for any help again.

Is this an engineering class?  Are you just trying to get it to work?  Or do you care about the parameters as well?  When you say you are only allowed to use the magnet, does that include the top plate, back plate, and pole piece?  What about the voice coil and former?  If you can provide more information on this project, we should be able to help you a little better.  But it sure does sound like a fun project.

Steven Kephart

Adire Audio

Is it going to be mounted on a baffle?  Or do you guys test it just free air?  If the latter is true then the surround doesn't necessarily have to be air tight as it won't make much difference.  My guess is that most people will try to wrap construction paper into a cone shape.  I recommend using a "flat" cone if the former is long enough.  I think that will ease the construction with no real negative effects considering you aren't looking for the flatest frequency response.  You can use cardboard, or even balsa wood.  For the suspension you need something that will prevent lateral movement, and will progressively stiffen up as you move in or out.  For the coil, I recommend keeping it short.  This will reduce mass and therefore increase efficiency.  Do you know what the gap height is on the motor you are to use?  Do you have to hit a certain impedance with the voice coil?

Steven Kephart

Adire Audio

Wow, I like the idea of the top of a plastic bottle.  For a surround, try cutting up an old innertube.  And to keep it centered, you can get a piece of teflon and cut it to where the former slides on it (slider bearing).  This should keep it centered and it shouldn't "chuff".  For the coil, you can buy coil wire online pretty cheap.  But if you will cover shipping, we can send you a couple coils from broken subs.  All you would have to do is un-wind them and wind them up on your new former. 

Steven Kephart

Adire Audio