Step 14: Controlling Gain -- Easy Way
The gain of the LM386, as the ATS is currently constructed, is set only to 20. The effect of this is that the ATS is not terribly loud. I found that to get desired volume, I had to turn up the volume of my MP3 player almost to its maximum level. This distorted the signal and sound from the ATS, and, poor speaker aside, result in very poor sound. The amplification of the system should take place in the LM386 (where it belongs) and not in the source providing the signal.
Careful examination of the PCB will reveal two pads just above pins 1 and 8 of the LM386. By joining these two pins with a piece of wire, the gain will be set to 200 and the ATS will be considerably louder. The datasheet for the LM386 indicates a 10uF capacitor should join these pins and that pin 7 needs a bypass capacitor. I have not noticed any problems with a simple wire.
This is the easy way to modify the gain. A more elegant and complicated approach is detailed on the next page.
Careful examination of the PCB will reveal two pads just above pins 1 and 8 of the LM386. By joining these two pins with a piece of wire, the gain will be set to 200 and the ATS will be considerably louder. The datasheet for the LM386 indicates a 10uF capacitor should join these pins and that pin 7 needs a bypass capacitor. I have not noticed any problems with a simple wire.
This is the easy way to modify the gain. A more elegant and complicated approach is detailed on the next page.
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