Project: multiple speakers for an ipod

[Labrite34]

Hey all,

I am hoping to make a system that can play multiple, varying sized speakers. I want to frankenstein this with speakers I can find around my house. I have a bunch of old computer speakers and even a few subwoofers which I would like to utilize (if possible). I am assuming that I need to make a highpass and lowpass filter (highpass to the smaller speakers, lowpass to the largers). I want it to run on, I suppose, two 9-volt batteries.

Just looking for some direction from you guys: steps needed to start my design. How I can properly power the multiple varying sized speakers? I do have a Digital Circuits book with Class-A and Class-B amplifier tutorials in it (but I never asked my teacher for guidance with this sort of thing).

I am hoping to build this on a board and epoxy it solid. What things should I be aware of? Please point me in the right direction! Thanks all.

 

[Labrite34]

I measured the resistances of a few various speakers; 5.6Ω, 6.0Ω, and 30Ω from small headphone speakers (which I am assuming are pointless to use). If I were to use, let's say 4 speakers, it would be much easier if they were all of the same resistance so I could wire them in parallel... but if they were different, could I simply match the speakers resistance to the highest (by adding a resistor in series to the lower resistance speakers)?? Will it be draw too much power to power 4 speakers that are 5 ohm?

 

[jim hardy]

I suggest dis-assembling those speakers and identifying the IC amplifiers the manufacturers used.
You'll find very clever audio amplifiers and reading their datasheets(which you'll find on internet) is quite educational. With a little effort you can figure out how to hook them up.

You won't run a subwoofer from a 9V battery, but you'll find interesting audio amplifiers inside most subs.
For now stick to powering them with wall mounted transformers similar to this:
http://www.mpja.com/12VDC1A-Plug-Supply-Hon-Kwang/productinfo/19466 PS/

 

[Labrite34]

I want to build a circuit what takes the signal from my iPod's aux cable, amplifies it, and plays it on speakers. I want to use multiple speakers with various resistances. What kind of an amplifier can I build? Should the speakers be wired in series, or parallel? Should I use resistors in series with the lowered rated resistance speakers to equalize them all to the same resistance? Thanks

 

[jim hardy]

I'd suggest you digest this hobby thread, which was started by somebody with the same question.

http://www.discovercircuits.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=7744&page=1

then check some of the audio sites mentioned in that thread.

You can have a lot of fun with hi-fi these days, there's kits for anything from tube amplifiers to the modern switchers.

 

[Labrite34]

If I wanted to power a bunch of different speakers, at different resistances, what should I do? I want to have 6 speakers being powered, but some are 6 ohm, some are 4 ohm and some at 8 ohm. I found a few schematics which give me a good idea, but they all are powering one speaker.