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General Asylum General audio topics that don't fit into specific categories. |
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General Asylum General audio topics that don't fit into specific categories. |
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In Reply to: I find that response lacks thought. ... posted by andyr on March 3, 2015 at 19:12:00:
Well, think about this: That very metal case also keeps the RF from escaping so once in it can bounce around and have many more chances of being detected by a susceptible node than if it were just passing through.
The main thing that shielding does for you on audio stuff like preamps is to keep the E-field hum that your bod picks up from the house wiring from coupling into High-Z nodes in the amplifier when you reach out to adjust it. It's usually more of a problem with tubes since they tend to be higher impedance devices than transistors. But it takes very little to stop it on say a breadboard, if you just mount the controls on small pieces of metal screwed to the board and ground them at a single point, say where the minus power comes in that will do the trick.
If you have an actual ether-borne RFI problem in home entertainment stuff it's usually energy coming in on the speaker cables and getting detected by the output bugs or crap coming in on the power line and detected by the power supply rectifiers. The cure is to add RF common mode impedance to your power and/or speaker cables with Z-beads. They have to be applied correctly however: they must be used only where your signal currents are differential and both sides have to go through the same path. Fortunately your speaker cables and power cord (if it doesn't have a ground wire) meet that requirement.
Radio Rick
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Follow Ups
- RE: I find that response lacks thought. ... - rick_m 20:42:26 03/03/15 (1)
- Very interesting and very true - thanks, Rick. ... - andyr 14:16:36 03/04/15 (0)
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