Bypass cap Layout with Discrete circuits

[guavatone]

http://www.analog.com/library/analogdialogue/archives/39-09/layout.pdf

I found Samuel's link in the Ground plane thread and posted it above. This is mostly about monolithics but what about discrete circuit stuff? Like a simple JFET buffer?

Like this:
http://www.avensonaudio.com/tech/MP-2NV%2520DI.jpg

It seems that C28 and C29 are following the rules in that article for being close to the Voltage supply on one end and then being close to the load resistor R66. Those rules are implied in that schem, right?

Also, that chart seems more concerned with High frequency ckts over 1MHz. Does anyone have a similar chart for Audio Frequencies? Are there standard ratios between cap values that are best?

 

[Samuel Groner]

Also, that chart seems more concerned with high frequency circuits over 1 MHz. Does anyone have a similar chart for audio frequencies? Are there standard ratios between cap values that are best?

Power supply bypassing is done at high frequencies to avoid oscillation, even if the frequency of interest (say 20 Hz to 20 kHz for audio) is much lower.

Bypassing at much lower frequencies--and usually with an additional series resistor (R68 on the GR schematic) to aid effectiveness--is usually only necessary if the amplifer has relatively poor PSRR, high gain and/or the supply shows exaggerated noise and ripple. Paralleling capacitors of different value is not necessary as they show acceptable impedance behaviour below about 100 kHz.

Samuel