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Step back and analyze the distortion. There are two probable causes for it, within the limitations of the LM386 itself:
1. the loudspeaker can't take the power level,
2. the battery can't supply enough current.
If you are using the loudspeaker 'open' (not in an enclosure) it may not be able to handle even the 0.5W maximum the LM386 can produce. Loudspeaker ratings are usually based on them being in a box. It may sound crazy but there is a reason for it, in a box there is isolation between the front of the cone and the rear. If there is no isolation the air pressure waves from one side of the cone take the shortest route to the other side which is around the edge. Remember that for air compression on side side there is equal de-compression on the other. Pushing a pressure wave out at the front sucks it back in at the rear! It results in the cone being too free to move and it deforms, producing distortion as it does so. Also consider that many loudspeakers made in a certain geographic area are rated by picking a random number just a bit higher than the random number their competitors used to give them a sales advantage.
The battery can also be responsible for distortion. To produce 0.5W from a 9V supply into 8 Ohms and assuming say 75% efficiency (I'm being kind to the LM386!) the peak current would be around 100mA. Standard 6LR61/6LF22 can't sustain full voltage under that load, even when new. As the volume increases the LM386 draws more current and that in turn drops the battery voltage. As the voltage drops, so does the maximum volume the LM386 can manage so you get the peaks being dropped more than the quieter sounds and that makes it sound distorted too. Ideally you need either a big battery or better still a regulated power supply that compensates for the extra current to maintain a stable 9V output.
Brian.
1. the loudspeaker can't take the power level,
2. the battery can't supply enough current.
If you are using the loudspeaker 'open' (not in an enclosure) it may not be able to handle even the 0.5W maximum the LM386 can produce. Loudspeaker ratings are usually based on them being in a box. It may sound crazy but there is a reason for it, in a box there is isolation between the front of the cone and the rear. If there is no isolation the air pressure waves from one side of the cone take the shortest route to the other side which is around the edge. Remember that for air compression on side side there is equal de-compression on the other. Pushing a pressure wave out at the front sucks it back in at the rear! It results in the cone being too free to move and it deforms, producing distortion as it does so. Also consider that many loudspeakers made in a certain geographic area are rated by picking a random number just a bit higher than the random number their competitors used to give them a sales advantage.
The battery can also be responsible for distortion. To produce 0.5W from a 9V supply into 8 Ohms and assuming say 75% efficiency (I'm being kind to the LM386!) the peak current would be around 100mA. Standard 6LR61/6LF22 can't sustain full voltage under that load, even when new. As the volume increases the LM386 draws more current and that in turn drops the battery voltage. As the voltage drops, so does the maximum volume the LM386 can manage so you get the peaks being dropped more than the quieter sounds and that makes it sound distorted too. Ideally you need either a big battery or better still a regulated power supply that compensates for the extra current to maintain a stable 9V output.
Brian.
