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That's crazy nonsense IMHO....

Posted by AbeCollins (A) on January 3, 2017 at 09:35:47

In Reply to: 6800uf across op amp PS pins? posted by Tweaker456 on January 3, 2017 at 08:34:32:

That's way too much capacitance to place right at the opamp PS pins. You might see that much filter capacitance or more within the power supply itself but not typically right at the opamp +V and/or -V pins.

A modest amount of bypass capacitance can be added where the power supply leads enter the printed circuit board assembly, perhaps 10uF - 100uF. And then a much smaller amount of bypass capacitance right at the opamp PS pins, typically 0.1uF. More is not better because the larger capacitors and their internal inductance offset their effectiveness at bypassing higher frequencies. You'll sometimes see a slightly larger capacitor in parallel with a much smaller one as their undesired inductance is reduced while their respective capacitance values can cover a wider bandwidth for bypassing.

Power supply decoupling is similar to bypassing but the focus is on minimizing signal transfer between stages. A small amount of series inductance can be used comprised of a ferrite bead over a short length of buss wire that feeds -V & +V right at the opamp pins. Different ferrite materials are effective over different frequency ranges. Charts are available from ferrite manufacturers.

Of course audiophiles will go overboard thinking that more is better everywhere. For practical purposes none of this is all that critical until you're in the RF range, using very high bandwidth opamps that are inherently not very stable, and involving high transient currents.

Edits: 01/03/17

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