Sunday, March 17, 2013

UROP speakers

This is another awesome project I get paid to do as part of my UROP. I'm designing a set of cheap and easy speakers destined to be made by course 6 Freshmen. It's a neat design challenge because the name of the game isn't make the best thing you can, it's make the best thing that someone else can make, oh, and they have no fabrication experience.

At the beginning of this project I spent a lot of time online looking for easy ways to build decent speakers. This is a small sampling of what's out there.

These all have some pros and cons I won't go into here, but the short of it is I wasn't happy with any of these.Using PVC or some other pipe seemed like a good idea. To get a decent volume though you need to use some fairly large pipe, which in itself isn't a bag thing, but sealing the ends gets tricky.

Typically pipe end caps are somewhat rounded on the end and schedule 40 PVC fitings at this diameter get pricey.

After about 5 hours of internet research I was able to confirm that a manufacturer did make a 6" PVC end cap for sewer drainage pipe that was flat on the face. Score.

I have some decent experience with different speaker drivers and designs. It's been a hobby of mine for years. Cheap, easy, and good brings to my mind the HiVi B3S. It's a little 3" fullrange driver that I've used before and costs about $12. They aren't very efficient but watts are cheap these days. After some simulation using WinISD and a bit of CAD is SketchUp here's what I had.

Leeb gave me the go ahead to build one, so that's what I did.

It sounds alright, nothing mind blowing, but definitely worth the time especially for people with little to no experience building speakers.

The plan is to build some more variations on the design (ported, sealed but bigger, filters) and quantify the differences. A big point of emphasis in this project is to show the students that these design choices are not arbitrary and do affect the final result. To do this the lab has bought two measurement microphones from miniDSP that I get to learn how to use. The plan now is to get the speakers together over spring break and start measuring the week after.

Until next time.