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I would like to understand how the center tap terminal work in miniature speakers. I can see in the datasheet that a positive going voltage relative to this center tap can lower the output volume but it does not specify by how much?

How can I calculate that? How is the actual connection between the 3 pads?

Maybe it is just a parallel connection between the positive pad - the center tap terminal and half the speaker resistance. I just want to be sure of this.

Thanks for your help.

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    \$\begingroup\$ knowles.com/eng/content/download/4788/66554/version/2/file/… \$\endgroup\$ – the_moon Jul 20 '16 at 18:40
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    \$\begingroup\$ Without the manufacturer telling you, I think the only way is to measure the coil inductance or resistance at the two points? I'm guessing a center tap would likely be centered, so everything would be halved? Just an educated guess. \$\endgroup\$ – Passerby Jul 20 '16 at 19:59
  • \$\begingroup\$ Why is it for? To modify the impedance of the speaker? \$\endgroup\$ – the_moon Jul 20 '16 at 21:08
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    \$\begingroup\$ I'm guessing yes. Half the coil, half the power? Like using a center tap on a transformer leading to a smaller voltage or current. \$\endgroup\$ – Passerby Jul 20 '16 at 21:10
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"a positive going voltage relative to this center tap can lower the output volume".

The datasheet doesn't actually say that. It says that "a positive going voltage... will cause a decrease in pressure at the sound outlet". I think that all it is saying is that when you apply a positive voltage as specified the internal diaphragm / speaker effectively moves inward causing a reduction in pressure at the sound outlet. You need to drive this unit with an audio signal exactly as you would a speaker.

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  • \$\begingroup\$ So, I do not get why is the center tap terminal for. What would cause a decrease in pressure at the sound outlet? \$\endgroup\$ – the_moon Jul 20 '16 at 21:06
  • \$\begingroup\$ Op knows they connect an audio signal, but if they use the center tap instead of the two outside taps, how much would it be reduced by. \$\endgroup\$ – Passerby Jul 20 '16 at 21:08
  • \$\begingroup\$ @Passerby I was trying to correct the OP's confusion between output volume and pressure at the sound outlet. \$\endgroup\$ – Steve G Jul 20 '16 at 21:19

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