Fnord wrote:Radio shack still sells kits for stuff?!?buy one of the small amplifier kit from electronics stores like radio shack.
idk i'm from Australia, just guessing
Fnord wrote:Radio shack still sells kits for stuff?!?buy one of the small amplifier kit from electronics stores like radio shack.
One thing to note about amplifier power. To achieve a 3 db gain (only a modest increase) to any perceived sound pressure level, you will always have to DOUBLE to wattage of the signal to the speaker. So, if you are driving a speaker at 80 db using 1 watt of power, you will have to increase it to 2 watts to increase to output to 83 db, then go to 4 watts to increase to 86db! And here's the kicker, if you were driving a speaker at 80db with 10 watts of power (really inefficient) it would take 20 watts to increase the level to 83 db. It's all relative.Technician1002 wrote:I find the way they rate amplifiers is designed to decieve. The 2X40 watt amp is listed at putting out 80 watts total, but only draws about 12. I like to know that the amp's real power is as measured in RMS watts out per channel with both channels driven. That way you can compare apples to apples, instead of some vague standard such as max peak power total.
In the ratings game, that amp is listed as a 2X25 watt model. They were kind enough to provide the conditions at which the measurement is made. That is only a 5 watt amp with distortion below 0.08% into 8 ohms or 10 watt into 4 ohms. The higher values is with 10% distortion. Many amps are power rated at high distortion levels to inflate the wattage number for advertising. Due to this some of my 25 watt amps (RMS with distortion below 0.01%) are higher power than many 250 watt amps.starman wrote:Here's a good place to start for a modern class D (digital) amp, 2 watts - 100 watts your choice. Can drive 4 ohm car speakers in good shape.
The 2 x 25W model should serve you well for this project and is only $26.
Sorry for all the theoriticals here. Car speakers are typically 4 ohms and will probably overload and just shutdown the little mp3 speaker system you were talking about so I wouldn't waste the money on doing that. If you want that big sound you were talking about, you're going to have to step it up a bit. Otherwise, you could just go with a set of computer speakers, already designed for what you are talking about.warhead052 wrote:Remember this, I don't want to spend more than I really need to. This project is more of a "lets see if I can really do it" and a "practice" project so I can get better with soldering and electrical.
I think I mentioned they would be fine for an MP3 player amp.Those 2 x 25w will be more than enough for what he's doing.
For battery operation, the trade off is highly recommended.