PS caps near amplifiers

A*P*I has C1 and C2 close to the DOA. What is the purpose of these? Like a battery reserve? Is this also the function of the Phantom PS caps close to the Mic Input?

A little more info of which api your talking about and the schematic would be cool to undestand what you want to know:roll:

What I guess without seeing it is that you´re talking about decoupling caps. If you put them close to the DOA they are a HF shortcut for unwanted noise on the power rails.
:guinness:

could these caps prevent oscillation too?

Here it is. sorry i forgot to mention 312.

They lower the impedance of the power rails, which can be important when the power supply is an unknown distance from the opamp - in a console it could be several meters away. Without those caps the resistance of the wire between the PSU and opamp will make the rails sag when the opamp doing lots of work, like passing loud bass notes. So decoupling caps like that often improve the low end. Its also common practice to have 0.1uF caps in the same place to stop HF oscilation on the power rails.


M@