Tda7284 Amplificador De Audio Bajo Ruido Stereo Itytarg

We were intrigued by the datasheet claims for Automatic Level Control (ALC a.k.a Automatic Gain Control, AGC) and wanted to see if this simple looking Op-Amp was as good as promised. We bench tested the basic circuit above and were very impressed with the results! We've included all the documentation we have for this part. Please review it and ask questions before you bid. We'll let you take it from here.

COMPRESSION vs CLIPPING
You may have heard of 'Speech Clippers'. Clippers limit audio peaks to a fixed level. But clippers don't regulate the gain; they just abruptly chop off the audio peaks. Clipping is a poor choice in controlling output level by sacrificing quality. Clipping produces severe distortion commonly heard as the popular 'fuzz' sound on guitar amps. Obviously, fuzzy speech is not desirable in voice communications. The TDA7284 does NOT employ clipping.

In strong contrast, the TDA7284, though simple to use, is much more sophisticated. It actually monitors the constantly changing output peaks and then varies the average circuit gain over a very wide range to maintain a virtually constant amplitude, distortion-free output. When the output level rises, the TDA7284 responds like having a very quick hand on the volume control, and reduces the gain to keep the output constant but without distortion. Similarly, when the output falls, it turns the gain up to keep the output level constant. [The original application of this IC was for use in auto cassette players. It functioned as low distortion pre-amp that could automatically and smoothly compensate for the wide ranging levels between cassette tapes or between songs on a tape.]

As expected, we found exceptional sensitivity and a wide dynamic input range. Our lab tests of the circuit shown above were impressive. The output quickly leveled off with a very low input signal and didn't change much after that. At very low levels, before compression kicked in, we measured 59 dB gain. ALC action began with an input below 1 mVRMS. As the input rose 39 dB from 1 mV to 90 mV, the amplifier output level (at approximately 1 VRMS) rose less than 1 dB. So we drove it harder to it's limit. Output distortion became noticeable on our scope when driven with a whopping 0.5 VRMS producing about 1.4 VRMS out. Simply put, cranking up the input approximately 500x, the output voltage didn't even double (2x).