Low ESR electrolytic caps in high gain circuits?

[J0K3RX]

Ok, I was doing some reading about low esr (equivalent series resistance) capacitors, electrolytic specifically. Can somebody tell me why or why not they should be considered in high gain, high frequency circuits? I have some idea but need some further understanding... I believe I should be using them (or it wouldn't hurt) on high gain preamp circuits, mainly for the power filter caps? Any thoughts or recommendations?  

I have read this but am still a little unsure/foggy?
http://www.illinoiscapacitor.com/pdf/Papers/low_ESR_fact_or_fiction.pdf
I know there is other stuff to read in regards to this but I need some "special education" short bus explanations since I'm kinda "special" if ya know what I mean...  

Thanks,
~ Jim

[GGBB]

Freaky - I read the same paper just a couple of days ago.  I'm not an expert on this by any means, but I believe that RFI noise in particular can creep in through the power supply and, in high gain circuits especially, end up having audible artifacts.  The common way around it is to parallel the electrolytic filter cap with a smaller film cap of 100nF or so which gives the RFI a low impedance path to ground around the higher ESR electrolytic.

[J0K3RX]

Freaky - I read the same paper just a couple of days ago.  I'm not an expert on this by any means, but I believe that RFI noise in particular can creep in through the power supply and, in high gain circuits especially, end up having audible artifacts.  The common way around it is to parallel the electrolytic filter cap with a smaller film cap of 100nF or so which gives the RFI a low impedance path to ground around the higher ESR electrolytic.

Excellent, thanks Gord! I was thinking the same after looking at some of the AMT circuits...

[R.G.]

Film caps come in several styles. Not all are particularly good for bypassing power.

Use ceramic 0.1 and 0.01s. Ideally monolithic or MLCC types.