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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: RE: Syllogism posted by madisonears on September 12, 2014 at 18:05:56:
Long ago I designed an amplifier (non-audio) that ran quite high voltages. It had linearity issues that I eventually traced to some MOX resistors. I'm not sure if it was tempco or voltage coefficient, but I've been wary of them every since, though they're probably fine in supply, loading or non-signal related locations.
In a different application some thin film SMT resistors were replaced with cheaper thick film. The noise increase made the circuits useless. You guessed it, I've been wary of them ever since. Again, they're appropriate in many spots, but not in my audio circuits.
Having replaced bunches of carbon comps that drifted high in value or became crazy noisy over the years, I can't see using them except as a special effect. Once they drift, I haven't seen baking bring them back. IMO, desiccant storage is probably a very good idea.
Those are all real measurable effects. What I haven't seen is any artifact resulting from the use of decent metal films (or foils) that would lead me to believe an improvement could be had. I could fault (or praise) them in a DC metrology application for ppm level drifts or changes in value from soldering or the generation of thermocouple voltages, but those things just don't show up in (my) audio applications.
In a solid state amp the two most important resistors are probably the feedback resistors, as any imperfection there becomes a fundamental part of the amp performance. Those, and the input stage, are where the right parts probably make the most difference. Carbon comps aren't suitable, wire wounds aren't suitable, thick film isn't suitable, MOX isn't suitable, so what does that leave us? Metal film and foil. Then it's just a question of what brand and specifications.
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Follow Ups
- RE: Syllogism - Old nuff 2 no better 07:12:30 09/13/14 (5)
- question - unclestu 14:32:51 09/13/14 (4)
- RE: question - Old nuff 2 no better 16:16:59 09/13/14 (0)
- Do some wire wounds cause rollofff? - airtime 15:25:59 09/13/14 (2)
- RE: Do some wire wounds cause rollofff? - unclestu 16:14:24 09/13/14 (1)
- Mills... - wheezer 17:28:22 09/13/14 (0)
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