My Speaker Amplifier Left Side Not Working

Adam Jenson

New member
Jun 18, 2019

This is my speaker amplifier board ,the left side which i marked as red circle is not working .It happend when I puted a capacitor by connecting + (capacitor) with + (audio output) and - (capacitor) with - (audio output ) on Subwoofer to filter high frequency noise .It was working for 30 min and suddenly the left output stoped producing sound ,at first i thought the subwoofer got destroyed but it was ok when i puted on right output .So my last remaing thing is capacitor which caused the trouble ,Is there any way to fix that output channel to work again or it is unfixable ?

Art Welter

Jan 11, 2011

For a single element passive crossover you should use an inductor (coil) in series with the woofer, the issue you have is likely driving a power signal into a short at high frequencies, as the capacitor in parallel with the speaker will shunt the current via the cap, and so it will tend to short out both the amp and speaker. It is far preferable to use filtering before the subwoofer input, as passive components for the subwoofer range are large, expensive, and waste power, and are difficult to design due to the speaker's impedance covering a very wide range, depending on frequency.
The output transistor(s) or other components in the amp may have burnt, replacing the bad components could fix the amp, but don't repeat the mistake.