Capacitors and resistors
Thu, 01/08/2015 - 17:12
Hi, Skip,
Would you mind sharing your thinking, in general, on the importance of brands and types of resistors and capacitors?
I know that some "old amp" guys (not to be confused with "old" amp guys) like to keep everything as close to old technology as possible, using carbon comp resistors everywhere, for example. But I think it's also true that using quieter types (wire-wound?) in early amplification stages is preferred by others.
And with regards to brands, are you particularly sold on specific brands of caps and resistors, or are most of them more or less equal to the ears of mortals?
Thanks for sharing your wisdom on this (and all of the previous questions you have addressed)!
Mark H.
Hello Mark- Thanks for writing. That is a big question, but here are some thoughts:
When I'm restoring (rather than modifying) a vintage amp, I'm almost always going to leave any components that are still working well. Evaluating caps and resistors is something that very few "techs" seem to want to do.....replacing them is easier and takes much less time! If I do need a part, my goal would be to use something that sounds as close to the original as possible.
I use vintage carbon comp Allen-Bradley resistors most of time, but any wirewound resistors should be replaced with wirewound.
For electrolytic caps that need replacing, I usually use current-production caps from IC, Sprague, or F&T. Many people assume that Sprague caps are made in the USA but I seriously doubt it. Sprague moved production to Mexico in the seventies and it seems very unlikely that they returned to the USA.
Signal and tone caps can be tough. It is very difficult to source working NOS caps from the forties, fifties, and sixties. Also many NOS caps have drifted in capacitance and even worse, are "leaking" DC voltage, something that is a serious no-no. I usually stick with Illinois Capacitor MWR-types. Vintage caps that are usually good would include disc caps, Sprague Orange Drops, and blue Mallorys as used in sixties Fenders.