What value of rail caps ( close to output transistors ) to use on an amp ?. 100 - 220 uf + 10uf + 100nF per rail good idea ? stereo PCB . is one 1000uf per rail to much? + 100nF.
" Main PCB " for Bridge rectifier and rail caps are 2x 10.000uF + 2x 100nF.
" Main PCB " for Bridge rectifier and rail caps are 2x 10.000uF + 2x 100nF.
Their purpose is stability and low rail impedance at higher frequency (where PSRR falls off), 100uF is often used. I don't think 100nF does much for high current output stages, but extra capacitance isn't going to hurt.
Depending on the capacitor the 100nF may be better than the 100uF up in the 100kHz + range. And either will be better than a very large capacitor up there. Going into the MHz a non-audiophile-apprioved class 2 ceramic will beat the pants off an expensive Wima film cap (lower L).
Your amplifier may or may not even care about decoupling at extremely high frequency, but it might. It will certainly matter in the 10-300 kHz range, where whatever capacitor you use has to be “good”.
Your amplifier may or may not even care about decoupling at extremely high frequency, but it might. It will certainly matter in the 10-300 kHz range, where whatever capacitor you use has to be “good”.
Modern low impedance electrolytic caps make most of the traditional extra bypass caps added in DIY builds redundant, if you are to benefit from extra ceramics the PCB layout better be good or you can get weird resonances instead. Here is one example from Sanyo, unfortunately this is not data common in the datasheets.
