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K&K Audio / Lundahl Transformers Welcome! Need support, you got it. Or share youe ideas and experiences. |
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K&K Audio / Lundahl Transformers Welcome! Need support, you got it. Or share youe ideas and experiences. |
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In Reply to: Harmonic Equalizer posted by Dave Davenport on June 7, 2004 at 05:59:53:
As far as I can tell, the merits and demerits of various cathode-bypassing schemes have little or nothing to do with power supply rejection ratio (PSRR), but a lot more to do with shaping the harmonic fall-off and carefully defining the current loop between plate and cathode.
This is a good thing, not bad. Rejecting PS noise is really a separate exercise than controlling loop behaviour. Noise measurements ignore important matters like PS noise/hum being impressed on the signal - which takes a spectrum analyzer with the ability to examine close-in sidebands 120Hz away from the main signal. The hazard with some PS noise-cancellation techniques is reducing noise without reducing modulation effects - which leaves you worse off than you started, in terms of "electronic" coloration.I prefer B+ diodes with very soft switching characteristics, which reduces the dV/dT and dI/dT across the transformer primary and the first filter element of the power supply. It's also the reason I avoid solid-state bridges and 10,000uF cap-filter supplies for the tube heaters - the current pulses going into the first cap are really large, and radiate 120Hz comb-spectra transients into the air and back out the power cord.
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- Grunge - Lynn Olson 18:54:41 06/08/04 (0)
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