[jangles2412]

I need major help on a speaker project i am doing for physics. I have a 10 inch sub woofer, a 4 inch mid range and a tweeter. I have no idea on where to start for my crossover. I don't know what I am doing with any of the wiring. If anybody knows about schematic diagrams for this type of speaker, please let me know. If you can come up with a schematic diagram for this type that would be great.  

[Danny Richie]

You'll need to design a crossover (filter system) to limit the range of the signal that each driver receives.

Start with the woofer: You'll need to remove the high frequency ranges from reaching it. Start with a large value inductor. Guessing that all your drivers are 8 ohms, try a value in the 12mH to 8mH range.

On to the Mid: You'll need to remove the lows and the highs from it allowing it to cover a range from about 200Hz to about 2.5kHz. So try a cap with the value of about 75uF to 47uF followed by an inductor that is between 2.0mH and 1.0mH.

On the tweeter: You just need to remove the lows only. So start with a cap in the 8.2uF to 4.7uF range.

You may also need to use some in line resistors with the tweeter and or tweeter and mid to balance the output down to the level of the woofer.

This is a basic first order approach and polarities may have to be reversed on one or more drivers as well.

Then get your teacher to help you shoot and impedance curve and a response curve of it to see where it is. I'd also recommend shooting each drivers response individually, and the sum of each of them, then allow all four measurements to be shown on one graph, like this:



Then post it here for additional guidance.

[S Clark]

Start by reading here http://www.diyaudioandvideo.com/FAQ/XOver/   and then go here http://www.diyaudioandvideo.com/Calculator/APCXOver/    Rh, Rm, and Rl is simply the Re value of the tweeter (h for high), midrange (m for mid) and woofer (l for low).   A glossary at the Parts Express site is pretty helpful for beginners.  See http://www.parts-express.com/resources/speaker-building-terms.cfm

More good reading here. http://www.parts-express.com/resources/building-a-crossover.cfm

This table will give you an idea what an inductor or capacitor will do in a circuit for 4 ohm and 8 ohm drivers.  You aren't likely to be lucky enough for your drivers to be exactly either 4 or 8 ohm, but it will give you an idea how and where capacitors and inductors affect the signal.  http://www.parts-express.com/resources/crossover-component-selection-guide.cfm  

You have a month to come up with this, and as you can see you have a lot of learning and reading to do.  Read about first order crossovers, second order crossovers, third.....  You were told up front that this was going to be a lot of work, so dig in and get started reading.  You have hours of reading before you can think about a theoretical design.  

And you haven't even started on phase issues.....

Your task is to come up with a schematic for a starting crossover design appropriate for the drivers that you have.  We have a measuring program, an old Clio, that will let you see what it looks like once we build what you put on paper.  Put in the time, and you'll come up with something good.  

[S Clark]

Jangles,
You have a PM that could help.
S Clark

[jangles2412]

Thank you for all the links and stuff to read. Hopefully that will help with my crossover. I'm still confused about my schematic diagram. I don't know where to look for a schematic diagram of this type of speaker. If you have any links for that, please let me know. I don't know if i should buy wires for this speaker or what. If so, what should i get?