choosing an audio amplifier 1

[leppy]

I need to choose an audio amplifier for a circuit I'm building. I hear there are several different types.. classA, class AB, class D, etc... However I'm not able to find information on these online. Can somebody tell me the difference between all these classes, as far as function, pros, cons, uses.. I'd like to have a clear comparison of them in mind upon which I can base my decision for which method to use. I'd appreciate any kind of info someone can give me. Thanks!

 

[OperaHouse]

I think they still make books. These can be wonderful sources of information. If you don't understand class A, B..., you can't design much of a circuit. Don't cheat yourself of an education.

 

[ScottyUK]

Have a look on Google for Douglas Self's books on audio amplifier design. Building amps used to be a hobby of mine, before work swallowed all my free time - I found his work very enlightening.

http://www.dself.dsl.pipex.com/ampins/ampins.htm

-----------------------------------

Start each new day with a smile.

Get it over with.

 

[felixc]

Do you want it cheap and dirty or do you want quality? Making volumes or one single home project? Take a look at the offerings from National Semiconductor. They also make excellent application notes about how to design audio stuff. Take a look.

 

[lcsjk]

You need to study a good bit in order to pick up the design differences in these, however:
A class A is a linear device with characteristics similar to those of an op-amp with higher power. In this case the output is on all the time, either driving or sinking current from the speaker load.

Class B is like having two opamps with one providing the output for the positive half cycle and the other providing the output for the second half cycle. THat way each one gets to be "off" for half the time. The problem is that as you change from positive to negative, you go through zero and op-amps have a high distortion as they try to work at circuit ground.

Class A-B is similar to B except both op-amps provide the signal as it crosses from positive to negative, so in the vicinity of zero, both are working and basically overlaping.

Class C and D get you into switch-mode operation and are a bit more complex to explain.

If this is your first design, learn the differences to your satisfction, and then stick with a class A.

 

[Chuckles159]

Before you start, how much power do you need and what kind of quality? No sense learning about everything about amps when all you need is 1 watt to drive a small speaker for a communications receiver.

Or do you need true high fidelity? Again. Reasonable or full blown audiophile.

Up to 60 Watts, National have a series of chips that you just wire up and go with. Not much thought needed.

For good audio amps, go to

http://www.diyaudio.com