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Tech Square Technical and speculative discussion of amps, cables and other topics. |
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Tech Square Technical and speculative discussion of amps, cables and other topics. |
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In Reply to: Resistor noise on AUDIO applications posted by megalomaniac on November 27, 2010 at 18:51:59:
Many resistors in solid-state amplifiers, such as collector load resistors or resistors in the biasing chain, see DC voltage. Perhaps the most important location is in biasing chains, since any excess noise (such as pink flicker or whatever you want to call low-frequency noise that depends on DC flow) will get amplified. Motchenbacher and Fitchin, followed by Motchenbacher and Connelly, included "noiseless biasing" circuits to minimize the effect at the input of solid-state amplifiers. If you are building a passive attenuator, then there should be no DC on the resistors. Another important feature, at which the good Vishay bulk foil resistors excel, is voltage co-efficient of resistance, which directly produces distortion. The worst resistors for that purpose are very short surface-mount high-megohm resistors of mediocre materials. I have measured > 0.1% variation on 0805 resistors in the 10 to 50 megohm range, varying the voltage from 1 to 10 V on a good DC bridge (assembled of GR wire-wound decade boxes).
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- RE: Resistor noise on AUDIO applications - TimFox 14:33:03 08/05/11 (0)
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