I have connected big capacitors to the speakers to increase the bass. Now, after months of using, I notice that one of the speakers sounds 2x low. I ejected those big capacitors, still the same. I don't know how to test the caps. So I'm asking theoretically, could those big caps have damaged the small ones?

  • \$\begingroup\$ How? Please draw a schematic. \$\endgroup\$
    – winny
    Aug 19, 2018 at 10:36

1 Answer 1


Unlikely, but yes.

A capacitor and the coil of the speaker form an oscillator, which will resonate to some frequencies more than at others. Resonance means you get larger voltages.

Adding resonance to a system can hence introduce voltages that you didn't design for. That can, in turn, break voltage-sensitive components such as capacitors.

Why it's unlikely: The smaller capacitor you used is probably sufficiently robust against overvoltage; also, speaker capacitors tend to be of the self-healing film type, so only a reduction in capacity would be noticable, with should shift the frequency response, but not lead to a reduction in output power with a sensible test signal (I assume that's what you mean with "2x low", whatever that exactly means).

More likely are cabling problems or a damaged speaker.

  • \$\begingroup\$ Isn't it class D something? \$\endgroup\$
    – user76844
    Aug 19, 2018 at 7:00
  • \$\begingroup\$ @GregoryKornblum lost me there, sorry? \$\endgroup\$ Aug 19, 2018 at 7:01
  • \$\begingroup\$ Unless he uses very old equipment, the amplifier should be Class D- switching stage. So no obvious oscillation. \$\endgroup\$
    – user76844
    Aug 19, 2018 at 7:03
  • 1
    \$\begingroup\$ @GregoryKornblum huh, there's a lot of real-world audio amplifiers that aren't class D, I thought. \$\endgroup\$ Aug 19, 2018 at 7:14
  • \$\begingroup\$ (this wouldn't be about class-X at all, by the way, but about the amplifier having a voltage feedback loop with a bandwidth >> audio bandwidth, right?) \$\endgroup\$ Aug 19, 2018 at 7:15

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