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Old September 24, 2009, 06:18 PM
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biff biff is offline
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Quote:
Originally Posted by vulcan500rider View Post
Maybe that's where I should be starting...Maybe if I knew WTF I was doing with crossovers, etc, I could just put together my own speaker kit...
I think you'd be getting in over your head, A book like that won't get you too far as the design process goes. I've dabbled a bit with XO design since the available simulation software is getting really good but I can tell you it's not easy. The design process goes like this:

- You need measured frequency response graphs and impedence graphs of the drivers you intend to use... assuming you picked ones that will play nice together to begin with.
- You import that data into a software package and simulate what effects the box (as in enclosure volume and port tuning frequency) will have on both the frequency response and impedence and save that.
- Then you take that data and import it into a different software package that with simulate what the physical shape of the box will do to that data. Here you need to state exactly where on the front baffle the speakers are. The distance the speaker is away from a box edge will give an effect called diffraction and you need to know what that is and decide if you want to offset the tweeter. You also have to add baffle step compensation. When the wavelength of the sound reaches the same length as the baffle is wide the sound will wrap around the speaker and you will be producing bass all the wat around the speaker not just in front. So in the listening position you just lost half the bass energy so you need to compensate for that. Then you also extrase phase information.
- Then you dump all this data into a crossover simulator and start designing the XO keeping track of cross over frequency vs. driver center to center spacing, making sure the signal gets to your ears time aligned and in proper phase after you have taken the into account the acoustic offset of each driver. You also have to make sure the impedence doesn't take any strange dips that could cause an amp's overload to trigger, and make sure the phase doesn't vary too far or you could drive your amp into oscillation.
- When you're happy with that you can build it, then voice it and/or run some measurements and then tweak the design for a few months till its just right.
- and I think I forgot some steps in there somewhere


...or you can build somebody else's published design that has already gone through this for you. The 'textbook' crossover books like that teach you won't get you close to what the above method will produce.

That big box is called a transmission line and apparently has very nice bass at the expense of a pretty large box. A ported enclosure will allow the driver to play lower and a sealed box will usually sound 'tighter' and be easier to integrate with a subwoofer. And yes drivers will lend them selves usually to one design or the other.

You might be pushing it on $200 but I'll see what I can dig up for designs without having to order parts from the U.S.. Actually making the XO is easy. Just twist the wires together as per the diagram and solder. Tiewrap it and hot glue it to a scrap board or pegboard and voila! I know it sounds slap'n'tack but most do it that way.

I'll get a list of links together, in the meantime anything you cantell me about your goals? Do you just want to focus on something that is just loud or I'm assuming focus more on sound quality, which will pretty much require small speakers for the $$$ you're looking at.

And for your reading pleasure , here's a build thread I made for my first build... which BTW could be a good design for you though I'm sure it will end up a little over your price goal.
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Last edited by biff; September 24, 2009 at 06:27 PM.
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