cheap computer speakers

[LightwaveDude]

I know there are already posts like this on the forum, but none are specific enough to my needs (or cheap enough).

The background: my girlfriend has just gotten a computer in her bedroom and she would like to have some speakers to play music on while she's in there. She asked me to buy her speakers, but I'd like to build some since most cheap computer speakers are cr@p.

I'm wondering how cheap I can build some speakers before it would be better to just buy a pair.

What I've come up with so far is this.

Tang Band W3-871S-----------$34.20
Sonic Impact T-Amp-------------$29.99
.7 mH inductor-------------------$5.24
6 ohm resistor-------------------$2.50
3.3 ohm resistor-----------------$2.50
8.2 uf poly cap-------------------$5.50
13.5 VDC 1700mA Adapter----$23.76
3.5mm M>M cable---------------$8.28
Shiping----------------------------$11.64

Total: $123.61

As you can see, I haven't added in the price of the enclosures or the materials needed to finish the enclosure.

I would be building the speakers following Zaph's designs with the W3-871S. To minimize price, I was thinking about leaving out the notch filter since they will not be used in a way even close to critical listening.

the main expense I don't want to deal with is the price of the T-amp and the power adapter. Both are quite expensive to be used with such for such cheap speakers, especially if only used for a computer system. I've looked for chip amp designs, but most are still no cheaper than the T-amp and then most require a torodial transformer which again, boosts the price again.

Are there any proven chip amp designs that could be built cheaper, and even better, are there any that could be built right into one of the enclosures to create a set of active computer speakers?

I'm not expecting anything better than lo- to mid-fi but I don't want to just take the easy way and buy some cheap computer speakers.

Any suggestions?

[TerryO]

I haven't looked at his site for awhile, but didn't he eventually go with a Hi-Vi B3S 3 inch driver as being better than the 371? That notch filter runs the cost up, which I'd try and avoid if at all possible. The Aura 3 inch is also a possibility and I seem to remember that people have used these without any filter elements.
Sorry I can't be of much help, I'm sure that it'll be a fun project.
Best Regards,
TerryO

[pjanda1]

Whichever driver you choose, you may as well try it first without the filter. It sure won't be difficult to add later if you choose. Also, you might be able to locate a cheaper power adapter. I don't think you could build a chip amp cheaper than $50 unless you can find some great surplus parts locally.

good luck,

Paul

[icurays1]

My logitech z2300's sound pretty amazing - and they can be had for about $80. 400 watts. thx. blah blah.

but where's the fun in that? build your own.

[LightwaveDude]

What about getting power supply parts from an old VCR I have laying around to play with, and a non functioning HP printer/fax machine I can aquire from work? Would I be able to use things such as the capacitors and maybe the ironcore toroid transformers?

I see that here he used all confiscated parts and he says it came out very well. Would it be possible to start aquiring old electronics and build a power supply with these, and maybe even the amp circut if I bought only the amp chip?

[Stocker]

If you have the time and space, tell all your friends, neighbours and coworkers that you are a happy electronics recipient, broken or otherwise. Take apart what they give you. It lends valuable (de)soldering practice and you can accumulate a vast store of useable parts. I have enough stuff gathered this way to not have to wonder if I have it anymore... I am surprised if I don't have something.

Collection...more than just a compulsive disorder, a useful hobby as well!

[icurays1]

Salvaging is fun. Invest in a desoldering iron, if you don't already have one - it'll prevent over heating parts.

Dont try to save small signal passives...those are so cheap it's not worth the effort. most modern circuits use surface mount stuff anyway, resistors and caps. big caps are the best thing to save, really.

of course, I'm not sure if you're going to find real hi-fi quality stuff in a broken vcr, though, like nice film caps for your crossovers, or inductors.

Check your junk stores and landfills (people toss some crazy stuff...) and have fun with it...but remember...your time is worth $$ too, so consider the $20 for a few parts if you're going to spend a few hours digging through junk to find what you need. sometimes you can find nice speakers at your Goodwill, too (i scored a pair of 1960's studio monitors for $5....)