Audio Output Signal & Capacitor on Tweeter

We have often seen that tweeters used for the BHs commonly added a capacity to the positive terminal, actually many swiftlet farmers even consultants do not really know on what and how the capacitor functions. Since many readers are questioning about that I try to give a short brief on this topic per my understanding.

Before understanding about capacitor, first we need to know how the sound is being transformed and produced. Many of us would think that audio output produced by the player or amplifier is Direct Current (DC), because output terminal of amplifier normally coloured with Red and Black which we always misunderstand as positive and negative of DC.

In fact audio signal outputted from audio player is a complex AC waveform, when the volume is low, the voltage out is low. Volume can be increased by increasing voltage wave with an amplifier. We are controlling the output voltage by setting volume knob level of amplifier. Tweeter (speaker) is to transform audio signal from AC waveform into sound wave, that’s why reverse two cables, tweeter still produce sound but AC phase will be reverse.


We may commonly see that tweeters added a capacitor to (+) terminal, some farmer might understand from the tweeter supplier that capacitor is to help to balance the sound volume when number of tweeters are looped up in parallel circuit, which is not true. Some supplier may also tell you that tweeter with capacitor will improve sound quality.

A capacitor's basic function is to pass AC current and block DC current. A capacitor will never pass DC current, where DC could harm the tweeters. Capacitor can also limit AC current depending on the frequency when high surge. The proper µF of capacitor should be selected for your tweeter for its impedance (ohm).

Generally capacitor is a protection of tweeter especially dynamic type tweeters. However I personally don’t think it has significant function for those piezo tweeters in our BH. If you wanted to improve tweeters sound balancing I will advise to use low resistance audio cable and consistence impedance of tweeter. Nevertheless I am not sound engineer but just to share with readers from my understanding, anyone specialised in audio want to correct my statement or share something, you can email to me.