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I have a cheap single-chip MP3-playing speaker. The kind you you get off eBay for $10. I want to make the output quieter (so I don't always have to adjust the digital volume controls).

The amp is a LTK8002D Class AB Audio Amplifier

I want to do this in a way that doesn't damage the circuitry. I only have basic electronics knowledge.

Should I do this with a potential divider? If so, should the total match the measured impedence of the speaker? The spec sheet says the speaker is 4 ohms.

Or should I do this with an inline resistor?

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2 Answers 2

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For this simple thing, where audio quality probably isn't very noticeable, just put an inline resistor in series with one of the speaker wires. A 4ohm should cut the sound roughly in half. But depending on your preference you may want a larger value. Make sure the resistor power is large enough for that amp. It says it's a 3W, but I doubt that it is being used at that level. Since the power will be split between the resistor and the speaker, you can probably use a 1/2W.

Sounds like a fun experiment, play and have fun!

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  • \$\begingroup\$ Placing resistor in series with speaker might distort frequency responce of the speaker. \$\endgroup\$
    – lvd
    Jul 3, 2019 at 17:21
  • \$\begingroup\$ It did, a bit. But it's only a quick and dirty job. \$\endgroup\$
    – Joe
    Jul 4, 2019 at 11:29
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According to the datasheet for the abovementioned LTK8002D, easiest yet correct way to make it queiter is to decrease Rf resistor value (alternatively, increase Ri value).

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  • \$\begingroup\$ Thanks, I'll try that at some point if the sound quality does get too bad. \$\endgroup\$
    – Joe
    Jul 4, 2019 at 11:30

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