Capacitors needed when using an audio amplifier?

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Discussion Overview

The discussion revolves around the necessity of using capacitors with an audio amplifier, specifically in the context of filtering DC current from the audio output. Participants explore whether the capacitors included on the amplifier's PCB are sufficient or if additional capacitors are needed on the output pins.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asserts that capacitors are mounted on the PCB of the amplifier and questions the need for additional capacitors on the output pins.
  • Another participant agrees that the capacitors on the PCB are sufficient, stating that no extra capacitors are required.
  • Some participants argue that while capacitors are necessary due to the single-ended supply of the TDA2822, they are not necessarily a best practice but rather a "necessary evil" when split supply rails are not available.
  • Concerns are raised about the size and specifications of DC blocking capacitors, particularly their impact on output impedance at low frequencies and the need for high ripple current ratings for higher output power.
  • There is a mention that allowing DC to pass to the speakers is undesirable, reinforcing the need for capacitors in certain configurations.

Areas of Agreement / Disagreement

Participants express differing views on whether the capacitors on the PCB are sufficient, with some asserting they are while others emphasize the necessity of additional capacitors depending on the configuration and supply type. The discussion remains unresolved regarding the best approach.

Contextual Notes

There are unresolved assumptions regarding the specific configuration of the amplifier and the implications of using or not using additional capacitors. The discussion also highlights the trade-offs involved in capacitor selection related to output impedance and power ratings.

toasterman
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Hello,
I am using this little audio amplifier with my Maximite computer: https://www.amazon.com/dp/B07MQ44KLP/?tag=pfamazon01-20
I know that it's a best practice to use capacitors on the audio output from amplifier chips to filter out any extra DC current. I am under the impression that the capacitors on this amplifier circuit will take care of that. Is this true, or should I use capacitors on the output pins also?

Thank you.
 
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I believe the capacitors you require are mounted on that PCB.
https://www.electroschematics.com/4375/tda-2822-stereo-amplifier/
 
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toasterman said:
I know that it's a best practice to use capacitors on the audio output from amplifier chips to filter out any extra DC current.

Thank you.

I wouldn't call it best practice, more a necessary evil if you don't have split supply rails.

Given the choice you would do balanced supply and have an output stage that does not have appreciable DC off set since DC blocking capacitors have to be huge to not impact the output impedance at low (bass) frequencies and need to have obnoxious ripple current ratings for anything more than a few W of output power.

The TDA2822 is single ended supply, so it would need them unless you run it in bridge mode, they look like they are on the PCB already!
 
toasterman said:
Is this true, or should I use capacitors on the output pins also?

no extra ones required
Baluncore said:
I believe the capacitors you require are mounted on that PCB.
https://www.electroschematics.com/4375/tda-2822-stereo-amplifier/
Agreed, yes they are :smile:

essenmein said:
I wouldn't call it best practice, more a necessary evil if you don't have split supply rails.
No, they are essential
essenmein said:
Given the choice you would do balanced supply and have an output stage that does not have appreciable DC off set since DC blocking capacitors have to be huge to not impact the output impedance at low (bass) frequencies and need to have obnoxious ripple current ratings for anything more than a few W of output power.

not to mention not letting DC pass to the speaker(s) which is a bad thing
 

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