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I know the audio output is line level, but what can I hope, in terms of volume, with a small passive speaker (without any LM386 amplifier) like this?

enter image description here

Basj
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2 Answers2

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TLDR: very little. It might be audible in a quiet room, but nowhere near loud enough to play any kind of music through (it may be good enough for Sonic Pi, but you may as well use headphones).

For any situation where other people might be talking, you will really want some kind of amplifier IC or circuit. Like you said, it is line level and is not designed to drive anything of significance.

Luke M
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Your speaker has an impedance of 4-8 Ohm (the value is usually printed on the back), while a line out typically has an impedance of at least 100 Ohm. If you connect this speaker to the line out directly, >90% of the power will be dissipated inside the RPi, and only 4-8% will reach the speaker.

You may try adding a small 1:10 audio transformer like this one:

enter image description here

The thick wire winding goes to the speaker side, the thin wire on the RPi side. This should increase the volume substantially, but don't expect miracles. If you need high volume, you have to use an amplifier.

Dmitry Grigoryev
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