Beginner Project - Crossover network

[jharig23]

Hi Everyone!  This is my first post on the forums.  I'm taking a linear electronics class on coursera.com, and I'm finding it very interesting, and not really as hard at I thought it would be. 

The first project I would like to make is a crossover network for a speaker.  This seems like a great starting point, since as far as I can tell, all I need to do is to design a high, low, and bandpass filter.  Would I be correct in thinking that the equiv. impedance of the total circuit (including speaker) should be 4 or 8 ohms?

Also, I'm concerned about the component selection.  There are so many different types of capacitors, and resistors.  Electrolytic, thin film, etc.  Also power rating.  Then inductors - should I try to wrap my own?  Maybe my first project should be to learn how to use my oscilloscope. 

Anyway, I'm very excited about the whole thing!  Any help or advice you can give me would be very appreciated!

Thank you!

James

[Zsola]

Hello!
The total impedance of the circuit should be the same of the output of the power amplifier. If it's not matched, the amplifier overheats (eg. the speaker have lower impedance) or distort. So it depends on what kind of amplifier you are using. Generally, an 8 Ohm speaker is safe on almost every amp, except headphone amps.
For parts, you can use polyester or polypropylene unipolar capacitors, they can whitstand over 63V (or even 630V). Normally, your power amplifier works on lower voltage (use at least double voltage cap!). If you want precise crossover frequencies, you can wind your own inductors, but if you want a quick one, you can use some power inductors if you can get around some mH.

You can see two nice calculators here:
http://www.diyaudioandvideo.com/Calculator/XOver/
http://www.diyaudioandvideo.com/Calculator/APCXOver/

Maybe some audiophiles ("audiofools"  ) can help too. I'm not that kind of nerd. Greetings!