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i'm in hte process of trying to build as thin as possible an audio amp. i have TDA 2003's, 741's, and 386's. i have seen many schematics online about different power level amps, but i dont have enough experience to know which of these IC's work best. any help is appreciated.
The 741 is not a power amp, it is a op amp. The TDA2003 provides the most power but needs large support components. The LM386 will work best for a low profile low power amp. Just google the part numbers for data sheets.
so after looking around here some, i see someone talked about a tda 2822m. would that be better then a 386? what i am trying to do is make an amp to hook to a 2.5" - 3" speaker and elect mic. its for a costume i am building and need this to be as thin as possible so i can install it on the inside of my front armor piece. as far as sound quality, i think this speaker is ok, i am not sure of its impedance though, and i am wondering now if i ran 2 speakers, if it would sound better with lower volume?
A TDA2822 has 14 pins. A TDA2822M has 8 pins.
they have two power amplifiers inside. When both amplifiers are bridged then the output power is more than 4 times more than the power from an LM386 power amplifier. They drive a single 8 ohm speaker.
Your idea of having a microphone and a speaker near each other will cause acoustical feedback howling because the mic will hear the speaker and the sound will go around and around forever. Feedback can be prevented if you "eat" the mic (very close to your mouth so the amplifier gain can be low) and mount the speaker on your shoe.
no way can i mount the speaker on my shoe. lol i have tried using other speaker amps and yea the biggest problem is feedback, is there anyway around this??
You can eliminate acousical feedback when the mic is in one room with the door closed and the speaker is in another room with the door closed.
Record your voice then play it back a little later.
Most mics pickup sounds from all directions. A few mics are directional (cardioid). A cardioid mic can point at your mouth and point away from the speaker.
so i was sitting here thinking about this amp thing, and i had a few other questions pop up. can you run 2 lm386's in series or parallel? what is the MOST important thing in clarity?? thats really what i'm looking for. i also found a bass boost for the lm386, but i wonder if you can do that PLUS still get the 200 gain from it also?
Power amplifiers in series or in parallel don't do anything useful.
Car radio amplifier ICs use two power amplifiers that are bridged to drive each speaker. The bridging effectively doubles the voltage swing across the speaker which also doubles the current resulting in 4 times as much power as a single power amplifier. Amplifiers that are bridged need to drive double the current of a single amplifier. The LM386 amplifier cannot drive double the current so it does not work properly when two are bridged.
The TDA2822 (16 pins) and TDA2822M (8 pins) are dual power amplifiers that can be bridged and have an output power that is more than 4 times the output power of an LM386.
Sound clarity is produced when the distortion is low (most modern amplifiers have low distortion), the speaker is good (your speaker is horrible) and the frequency bandwidth is not narrow (your speaker's bandwidth is probably narrow).
The bass boost circuit for the LM386 uses a gain of nearly 20 at low frequencies then it reduces the gain to nearly 10 at higher frequencies. I think adding a 10uF capacitor from pin 1 to pin 8 will produce a gain of 200 then the resistor and capacitor in series from the output to pin 1 will reduce the gain to 100 at higher frequencies and result in bass boost. Try it.
Not true, by paralleling amplifiers (and some chips are specifiically designed with this option in mind) you can feed a lower impedance and increase the power. The 'so called' gain clone amplifiers are often built that way.
However, unless it's designed specificaly to be used that way - NEVER attempt it.
Hi Nigel,
I have seen National Semi amplifier ICs paralleled with series output resistors so that they can drive almost double the current into 4 ohm speakers but I disagree with it because then the amplifier has a much higher output impedance that results in poor damping of the resonances of speakers.
In this application the speaker is 8 ohms and two paralleled amps won't make any difference.
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