Resistors

[rf7]

What do you pro guys use, when you're replacing resistors in a vintage amp? Do you use carbon comp., carbon film, metal film, or the higher priced stuff you can buy on Angela Instruments? Is it sacrilege to stick a metal film resistor in an old amp?
Just wondering.

[MWJB]

In a vintage amp it's worth discussing it with the owner. The merits of the various types are irrelevant if he doesn't like the look of the MFs, or even CFs that stand out like a sore thumb against the original carbon comps. In the preamp, it makes sense to go with the closest thing to original. Exceptions here might be plate resistors, especially regarding the higher voltages at PI/cathode followers, where I might go for 1W CF. Generally, noise concerns about 1/2W CC plate resistors are often exagerrated.

If the owner regards the amp as a "keeper" and isn't fussed about cosmetics/perceptions at resale, then whatever is at hand goes in, usually CF as I can get these quickest.

In other places, I'm less bothered about cosmetics and more bothered with practicality. Screen grids & power supply dropping resistors usually get upgraded with bullet proof parts, 4-5W wirewound in the former, 3W metal oxide in the latter.

Personally, I have only ever seen one brand of amp (vintage, modern or otherwise) that had MFs pretty well throughout. I know that there are others.