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I am trying to use an LM386 to drive some speakers. I have both a 4Ω 4W speaker and 8Ω 1.5W speaker. Would I have to build a different circuit for each of these and would the LM386 be able to drive both speakers in parallel at once?

Using the formula P=R(I^2), I would get that the 4W speaker needs 1A and the 1.5W speaker needs 0.43A, so can the LM386 handle 1.5A? Or is my logic here wrong?

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  • \$\begingroup\$ LM386 doesn't drive 4 ohms very well. It's a bit better driving 8 ohms but it's too low power to get the best out of either speaker. If you're stuck with it, use the 8 ohm spkr. \$\endgroup\$ – Brian Drummond Mar 12 '16 at 19:18
  • \$\begingroup\$ @BrianDrummond, could you explain why it wouldn't? Is the resistance of the speaker too low (and therefore a higher current)? \$\endgroup\$ – electricviolin Mar 12 '16 at 19:20
  • \$\begingroup\$ Read the datasheet. Note the power ratings into 4 and 8 ohm loads on the graphs. Or try it and see for yourself. \$\endgroup\$ – Brian Drummond Mar 12 '16 at 19:24
  • \$\begingroup\$ @BrianDrummond Okay, I see what you are saying. Could a parallel two of these ICs, or do they work like transistors where paralleling them would force one of them to take all the load? \$\endgroup\$ – electricviolin Mar 12 '16 at 19:30
  • \$\begingroup\$ You could try but it would be much simpler to use a more suitable amplifier. There are hundreds, I'm not going to suggest one. \$\endgroup\$ – Brian Drummond Mar 12 '16 at 19:33
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I would just use the 8Ω 1.5W if the only option is to drive the speaker directly because that chip is low power.

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