Power amplifier for audio

224

03:12:49

MDA2020/2010; TDA2020

published 11 years ago

thebugger

11 years ago

The input signal should be less than 140uV for a linear amplification. After that threshold cutoff distortion kicks in and THD rises dramatically.

rbrtkurtz

11 years ago

Input signal isn't the problem. This type of circuit relies on an op amp IC that has a set internal gain. The MDA2020 has an internal gain of 30db. That's just about 31.6V/V. The op amp used in this circuit has an internal gain of 100,000V/V, or 100db.

rbrtkurtz

11 years ago

I'm not talking about supply voltage. Set the op amp's gain to 31.6V/V. That is 30db, which is what the internal circuitry of the 2020 is set to. Look at the output. That's a square wave. It should be a sine wave, like the input. If the peaks of the wave are flat, that means the amp is clipping, and distorting. When it gets to the point that it's putting out a square wave, it's not even recognizable sound anymore. Go look at the datasheet for yourself, the gain is 30db, which equals 31.6V/V.

rbrtkurtz

11 years ago

Touch the op amp. It has the values you can change. Gain, minimum output, and maximum output. Set the gain to 31.6V/V. The default value is 100KV/V. The minimum and maximum output are the same as whatever your power supply is. If you're supplying + and - 18V to it, minimum is -18V, maximum is +18V. The gain is exactly what it sounds like. For every 1V difference between the - and + inputs, you'll get 31.6V at the output.

rbrtkurtz

11 years ago

Much better!

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