I'm currently designing a single rail power supply audio amplifier and just wondering what the benifits are (if any) and if its worth including a film/poly capacitor in parallel with the large electrolytic capacitor.

This is an example:

enter image description here

In short, are there any advantages to the 10uF poly capacitor? If so, what type would be best? MKP, MKS, PIO?

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    \$\begingroup\$ yes, electrolytic caps are far from perfect, especially at higher frequencies – however, if you're building a single-transistor feedback-less amplifier, you're most definitely not doing it because you're trying to build a hifi device, nor something that works like "real-world" audio amplifiers, so I'd honestly not bother. \$\endgroup\$ – Marcus Müller Sep 28 '19 at 17:44
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    \$\begingroup\$ I only included this image as a simple example circuit, my amp will have a preamp transistor stage with mosfet output and use global negetive feedback. \$\endgroup\$ – G Frank Sep 28 '19 at 17:47
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    \$\begingroup\$ please don't post misleading examples! Instead, post your own amplifier. Whether or not it makes a difference depends on your use case, output impedance, frequency range, flatness and linearity requirements. \$\endgroup\$ – Marcus Müller Sep 28 '19 at 17:53
  • \$\begingroup\$ I did but in bold: This is an example:. \$\endgroup\$ – G Frank Sep 28 '19 at 17:57
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    \$\begingroup\$ That poly capacitor is in parallel with the output capacitor, not in series. \$\endgroup\$ – Transistor Sep 28 '19 at 18:02

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