Electronic coupled noise: Difference between revisions
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=====Power conversion noise===== | =====Power conversion noise===== | ||
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Type: Conductive, in that it's its direct output | Type: | ||
: Conductive/resistive, in that it's its direct output | |||
: also often inductive/capacitive, because it's a bunch of current on wires nearby | |||
In the presence of rectification, there is a strong peak at 50 and 100Hz or 60 and 120Hz as well, | In the presence of rectification, there is a strong peak at 50 and 100Hz or 60 and 120Hz as well, | ||
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Switch-mode power supplies | Switch-mode power supplies ''in theory'' operate at dozens or hundreds of kHz, | ||
This tends to be ~60-100dB{{verify}} away for most frequencies but can be much closer for some. | which should avoid audio-frequency noise. | ||
...but even if they do they can still have some intermodulation, | |||
which is the interaction of different internal frequencies to cause some signal at lower and higher frequencies. | |||
This tends to be ~60-100dB{{verify}} away for most frequencies - but can be much closer for some. | |||
This is why switch-mode have a reputation that they're too noisy, though this depends on quality. | This is why switch-mode have a reputation that they're too noisy, though this depends on quality. | ||
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"Ground loop" has become the catch-all term for '''any of a handful of ground related issues''', | "Ground loop" has, over time, become the catch-all term for '''any of a handful of ground related issues''', | ||
each with their own distinct solution. | each with their own distinct solution. | ||
In | In a more literal sense, the name describes one or two out of a much larger pile, | ||
but the term is now abused so much you should assume it's any in that pile. | |||
You are better off reading 'ground loop' as 'people throwing a vague name at why the hell does my thing go bzzz'. | |||
It is a technical explanation only when talking to a technician. | |||
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Some things may absolutely be getting interference, but by merit of being fixed or not, | |||
either work or not. | |||
For example, DMX is usually hidden in the ceiling. Until you add something new up there, | |||
things probably mostly just work, or you are currently troubleshooting, | |||
but even then you leave it in a fairly fixed state. | |||
Audio setups may change every day, and it's easy to find a hum and start poking buttons and yanking things. | |||
Also, there are a lot of fixes based on "I heard" and "works for me" and any discussion of the actual issue, or safety is optional. | Also, there are a lot of fixes based on "I heard" and "works for me" and any discussion of the actual issue, or safety is optional. |
Revision as of 17:13, 19 April 2024