So this is a follow-up question to the one I posed below. I should have been more specific. Is the type of resistor critical in a power supply as long as dissipation rating is met? I am rebuilding my 300B SET and plan on using low noise resistors -- metal film or wirewound. For sound quality is one preferable to the other? And should I avoid ones that are the least bit magnetic? And if wirewound is the way to go, should I spring the extra money for non-inductive like Mills?
PSU resistors (like most other resistors) are uncritical. Ordinary commercial quality satisfying ordinary engineering requirements are fine.
Any modern metal film, metal oxide film, wire wound resistor will do fine. Just be mindful of the voltage ratings and derate the power dissipation by 3~4x. I.e. operate a 3 W rated resistor with no higher than 1 W of dissipated power.
If you operate the resistors at their full rated power, they get screaming hot (as in 250 ºC). Even with a 4x derating factor, they still reach 80~100 ºC with a 20 ºC ambient temperature.
~Tom
If you operate the resistors at their full rated power, they get screaming hot (as in 250 ºC). Even with a 4x derating factor, they still reach 80~100 ºC with a 20 ºC ambient temperature.
~Tom
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