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DigitalMan
08-18-2006, 04:47 AM
I've just obtained some decent-sized speakers, and I'm thinking it's time to give either the TV or the computer an audio·upgrade. But these things need power, apparently lots of it. Plugging them right into the audio out of my DVD player or the TV produces so little sound I'd need to strap them to my head like headphones to hear anything.

So, how do I go about amplifying these? I figure I got a solid 12 volt supply to use, but I don't know whether to put two LM386 half-watt amplifiers to use, or one of·my big, needs-a-giant-heatsink-and-a-CPU-fan 6-watt stereo amp chips. Cripes, I don't know if either are appropriate, I'd be better off if I could program the amps http://forums.parallax.com/images/smilies/smile.gif But essentially, I need these speakers to be of reasonable volume, without making them explode or something. Plus I need volume, treble, and maybe bass control.

And additionally, what would be used to add a subwoofer to the system?

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I think I shall assemble a circuit to run various·calculations, and control peripherals accordingly. I will give it some user input device, and perhaps a display screen to show data. But what would I call this device...

RDL2004
08-18-2006, 10:06 AM
You may be better off just buying a cheap receiver or amp off Ebay, but if you want to build one you might want to poke around here:

www.diyaudio.com/forums/ (http://www.diyaudio.com/forums/)

Look for the Chip Amps forum.

- Rick

Mike Green
08-18-2006, 10:25 AM
There are some nice Class D amplifiers now on the market.· Do·a web search for them.· They're digital amps and produce nice sound with minimal heatsinks.· There are some app notes that could guide you in making your own or you could buy some ready made.

Chris Savage
08-18-2006, 11:07 PM
I used to build custom audio amplifiers for a living...I still work on them from time to time as a hobby.· I am still using the LM3886TF for most designs.· I guess the real questions is, just how big are these speakers?· What is the rated power input?· Also check whether it's peak or RMS.· How many ohms?

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

DigitalMan
08-19-2006, 06:10 AM
Whoa, an LM3886TF is 68-watt, right? That's a lot bigger than what I've got, I'd better rip apart some stereos.

The speakers are just large normal stereo speakers, the back of the case·says they have 8-ohm impedance but that's about it. It's got a 5" speaker cone in each case, which is by no means huge, but it's definitely the biggest I've got. Probably not something that would require a·concert amp or anything.·I'm not sure I could take apart the case to get more info without destroying the case. Oh well, may as well try...

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I think I shall assemble a circuit to run various·calculations, and control peripherals accordingly. I will give it some user input device, and perhaps a display screen to show data. But what would I call this device...

Chris Savage
08-19-2006, 07:45 AM
DM,

·· I used to use the LM383 (8 Watts) for lower power projects.· You may have to shop around to find a deal on it, since last time I checked it was more expensive than the LM3886 (Which is 68W).· It's an easy TO-220-5 package with low external parts count.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

DigitalMan
08-19-2006, 11:23 AM
Well, in my giant mess of boards ripped from TV's I found an STK4362 10W stereo amp:
http://www.datasheetcatalog.com/datasheets_pdf/S/T/K/4/STK4362.shtml

And to help with the rest of what I need,·the same board conveniently has an AN5836 stereo volume/treble/bass/balance control chip:
http://www.datasheetcatalog.com/datasheets_pdf/A/N/5/8/AN5836.shtml

I'm going to guess that the control chip goes before the amp, considering the power they each use. Might need some transistors or even small transformers to get it all working together.·Does that sound like a suitable system?

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I think I shall assemble a circuit to run various·calculations, and control peripherals accordingly. I will give it some user input device, and perhaps a display screen to show data. But what would I call this device...