Questions about connecting 8 ohm amp to a 4 ohm speaker.

Hacdrag said:

none of the very informative replies, such as that from @MrAl were a waste, as I learned a lot from them.

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Note that MrAl only calculated power at the output of the amplifier as seen by the resistor and speaker. You can measure the current into the lm386 to determine if the system needs to consume equivalent or less power for similar audible volume levels because of various concumption in the chip.

Hacdrag said:

I wasn't aware of this. All vendor documentation states:

• 500mW maximum power output @ 8 ohms, without any mention of 4 ohms.

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https://www.ti.com/lit/ds/symlink/lm386.pdf shows in figure 6.1 that the output voltage limits at about 3.5 V pk-pk with a 4 Ohm speaker.

ZipZapOuch said:

From the Texas Instruments datasheet...

View attachment 148504

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The exact page I got it from