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I found this schematic and it says the speaker used is 5W and 8Ω. However, the speaker I have is a 5W and 3.2Ω. Will it work? What are the conditions? And what would be the effects?

And if it's okay, I want to modify this to work in stereo because I have two of these speakers. How will I do it?

5w class-a amplifier schematic

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    \$\begingroup\$ If you want stereo, you need two amplifiers, each feeding one of your two speakers. \$\endgroup\$ Sep 21, 2018 at 23:07
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    \$\begingroup\$ The vast majority of amps, including this one, tightly control voltage and let the current do what it does, as dictated by the speaker. So if you were to drive the intended speaker to the design limit, and then swap for your lower-impedance speaker, it would pull more current (V=IR) than the amp was meant for. It might survive, but that's nowhere near guaranteed. It would certainly run hotter. Limiting the output to far less than its technical capability may let you get away with this kind of mismatch, but in a fully-engineered system, it's far better to actually satisfy all the specs. \$\endgroup\$
    – AaronD
    Sep 22, 2018 at 4:36
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    \$\begingroup\$ Half the voltage. If you drive a 4 ohm speaker at 12v is like driving a 8 ohm speaker at 24V \$\endgroup\$
    – Passerby
    Sep 22, 2018 at 4:49

1 Answer 1

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You can add a resistor in series with your speaker. The resistor needs to be 4.8 ohm and can handle power dissipation of at least 3W.

Refer to this question below: Increasing resistance on speakers

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  • \$\begingroup\$ What if I used a 5W resistor? \$\endgroup\$
    – Ground
    Sep 26, 2018 at 10:09
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    \$\begingroup\$ it's fine as long as more than 3W, a 5W resistor means that it can safely dissipate 5W, but doesn't mean that it'll consume 5W. \$\endgroup\$
    – Zy Gan
    Sep 26, 2018 at 11:24

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