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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: Replacing 15,000uf Electrolytic w/ 3ea. of 4700uf BG posted by valvarez on November 27, 2005 at 06:41:06:
All tubes have their filaments in close proximity to their cathodes, and there is substantial capacitance between these electrodes. This makes the filament supply a possible source for audio noise. The way to tell, if you are building or modifying your equipment, is to rig up a temporary battery supply for the filaments, and switch between the internal supply and the battery supply while listening.If you hear no difference in audible noise without a signal, or signal attributes such as timbre purity or sibilant emphasis, then the internal filament supply is adequate.
If you do hear a difference, then attention to the filament supply is appropriate, and I would look into bypassing the electrolytic caps with high-quality film and silver-mica caps. Use a cascade of values down to 100 pF or so, since the very high frequencies pass easily through the filament-cathode capacitance. You want your bypass caps to be effective at frequencies above 1 GHz.
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Follow Ups
- Filament-to-cathode capacitance. - Al Sekela 13:19:45 11/27/05 (1)
- Re: Filament-to-cathode capacitance. - valvarez 10:23:35 11/29/05 (0)
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