Computer speakers

[ronv]

The speakers on this computer are just run from the audio jacks from the sound card and they can barely hear themselves. I would like to build a little amplifier so I can hear them. I can scrounge up a 12.6 volt 2 amp CT transformer. What would be a good IC to put with it? All the speakers I have around are small 8 ohm and could probably use some bass boost.
Thanks!

 

[audioguru]

There are many bridged car radio amplifier ICs like the TDA7240A that drives a 4 ohm speaker to 14W at clipping when the supply is 13.2VDC. An 8 ohm speaker will produce about 8W. But maybe your little speakers will blow up with more power than only 1W. The datasheet for the amplifier IC has the schematic and a recommended pcb design.

A little speaker has trouble producing bass frequencies. My computer speakers have 3" 4-ohm drivers with huge magnets and rubber surrounds and produce frequencies down to 80Hz (no deep bass) at about 3.5W each with a 12VDC/1A power supply.

 

[Reloadron]

If you want to build an amplifier that is fine. However, basic powered speakers for a computer system like these for example can be had pretty cheap. Cheaper than you could likely build just the amplifier for. Then if you want a sub woofer a set like these can also be had pretty cheap.

Your computer is giving you line out audio which really won't drive speakers directly.

Now if you want home brew the LM1877 might be a good choice. A Google of LM1877 circuits and the LM1877 data sheet should give you some ideas.

Ron

 

[audioguru]

There is no way the cheap and tiny 3" "sub-woofer" will produce frequencies as low as 30Hz. It will probably roll-off at 100Hz.

 

[MikeMl]

If I wanted a set of "powered speakers" for a computer, Ipod, Mp3 player or Portable DVD player, I would go to the local University Surplus store. They turn over computer equipment very quickly, and have tons (literally) of surplus computer equipment. A set of Bose speakers sells for $5. $5 more buys a powered subwoofer. A P3 sells for $20 (sans disk), keyboard for $5, CRT monitor for $10, etc.

 

[Reloadron]

There is no way the cheap and tiny 3" "sub-woofer" will produce frequencies as low as 30Hz. It will probably roll-off at 100Hz.

Yeah, well at $16.99 USD I wouldn't expect too much.

I like Mike's thinking and this isn't the first thread I have seen the university surplus store mentioned. A gold mine huh?

Ron

 

[MikeMl]

...

I like Mike's thinking and this isn't the first thread I have seen the university surplus store mentioned. A gold mine huh?

Ron

Yeah, half the junk in my workshop came from University Surplus, including lab power supplies, signal generators, oscilloscopes, computer equipment, parts, coax, two-way radios, etc. I used to work at the "U", and got in the habit of going over there on lunch breaks. As a retiree, I still visit it...