I had some recessed lighting installed and the default brightness is too bright, so I'm thinking about having a dimmer installed. But will installing one inevitably create a ground loop and induce buzzing somewhere in my audio system? As far as I know, the lights are on their own circuit (the power switch installed doesn't control anything else).
Will a dimmer switch create a ground loop if the lighting is on its own circuit?
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Dimmers can (usually do) buzz, but not because of ground loops. Much more here:
Hum and Buzz, Clicks and Pops
--Ethan
Dimmers can (usually do) buzz, but not because of ground loops. Much more here:
Hum and Buzz, Clicks and Pops
--Ethan
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Ethan, we used some special low-noise shielded dimmers in our church to fix their radiated/coupled noise issues but I cannot for the life of me remember who makes them. Do you have any suggestions?
In the past a capacitor across the dimmer (or LC filter) helped but requires a bit of technical knowledge both in component selection and soldering/mounting in the dimmer.
In the past a capacitor across the dimmer (or LC filter) helped but requires a bit of technical knowledge both in component selection and soldering/mounting in the dimmer.
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When I built my house I had the electricians install regular solid state dimmers, and crossed my fingers. Bad mistake. So then I replaced one dimmer with a $90 solid state model (1990s dollars) that claimed to not buzz. Fail. It was just as bad as the other. So I returned it and bought a bunch of Variacs.
The short answer is I don't know a brand of SS dimmer that doesn't buzz. I've seen some that include a large choke, which I assume works, but they're as bulky and expensive as a variable transformer.
--Ethan
The short answer is I don't know a brand of SS dimmer that doesn't buzz. I've seen some that include a large choke, which I assume works, but they're as bulky and expensive as a variable transformer.
--Ethan
I've never actually seen a dimmer that doesn't include a choke.
The most common consumer dimmers use a triac to chop the voltage somewhere other than the zero crossing, creating large amounts of rf hash.
The trend now is moving toward IGBT based dimmers which turn on at the zero crossing and ramp the voltage down at some point afterwords, these don't create hash and don't require a choke.
BTW, all dimmers are solid state, except those salt water dimmers not used since the 20's
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The most common consumer dimmers use a triac to chop the voltage somewhere other than the zero crossing, creating large amounts of rf hash.
The trend now is moving toward IGBT based dimmers which turn on at the zero crossing and ramp the voltage down at some point afterwords, these don't create hash and don't require a choke.
BTW, all dimmers are solid state, except those salt water dimmers not used since the 20's
The higher quality dimmers have much better RFI filters. So don't buy a bargin dimmer.
There were and still are auto transformer dimmers (Variacs) that are very clean electrically. But they are big, like need a 6x9 inch wall box for 600 watt capacity. Expensive too. These were always considered mandatory in any pro audio room but in the 1990s we started using good solid state dimmers and found they were OK electrical noise wise.
There were and still are auto transformer dimmers (Variacs) that are very clean electrically. But they are big, like need a 6x9 inch wall box for 600 watt capacity. Expensive too. These were always considered mandatory in any pro audio room but in the 1990s we started using good solid state dimmers and found they were OK electrical noise wise.
LOL, they called those "piss pots" because that's what they smelled like under load. My father was a theatrical set and costume designer and in the 1960s I hung around backstage during rehearsals at some Broadway theaters that still had them. But I don't think they were used anymore by that time.
After the salt water dimmers but before Variacs in the 1940s? they used pure resistance dimmers. I remember a bunker type storage room backstage with a lighting grid and power distribution. The chief electrician told me that was to "balance the old dimmers". It wasn't until went into engineering school that I really understood what he meant. They were simply resistive divider circuits and needed a minimum load to work properly.
Quote:
Originally Posted by SAM64 /t/1517148/will-a-dimmer-switch-cre...-lighting-is-on-its-own-circuit#post_24348380
......except those salt water dimmers not used since the 20's![]()
LOL, they called those "piss pots" because that's what they smelled like under load. My father was a theatrical set and costume designer and in the 1960s I hung around backstage during rehearsals at some Broadway theaters that still had them. But I don't think they were used anymore by that time.
After the salt water dimmers but before Variacs in the 1940s? they used pure resistance dimmers. I remember a bunker type storage room backstage with a lighting grid and power distribution. The chief electrician told me that was to "balance the old dimmers". It wasn't until went into engineering school that I really understood what he meant. They were simply resistive divider circuits and needed a minimum load to work properly.
I hear they produced chlorine and hydrogen from the electrolysis effect on the salt solution.
It's rare to see triac based dimmers in broadcasting anymore, almost all the new stuff is IGBT based (for incandescent loads) or FET (DC) based PWM control of LEDs.
It's rare to see triac based dimmers in broadcasting anymore, almost all the new stuff is IGBT based (for incandescent loads) or FET (DC) based PWM control of LEDs.
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I'll have to see if I can pry off a wall plate and see what we got for church a few years ago. They are SS, not Variacs, and IIRC used zero-voltage switching as well as including more filtering and such. I remember looking one over before it was installed but it was encased so not much to see. They did make the buzz go away...
For the record, Variacs (autoformers) are not a complete panacea. They can buzz (mechanically) as they age due to delamination (glue holding the wires dries and cracks), and they can develop dead spots and arc as you turn the knob. Once set they are quiet, but changing them with the system on and running with high gain can cause painfully loud pops. Don't ask how I know this.
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I used to add caps to suppress some of that, and more modern ones I have seen (very few, not in that biz no mo') include small RF filters (LC input/output).
For the record, Variacs (autoformers) are not a complete panacea. They can buzz (mechanically) as they age due to delamination (glue holding the wires dries and cracks), and they can develop dead spots and arc as you turn the knob. Once set they are quiet, but changing them with the system on and running with high gain can cause painfully loud pops. Don't ask how I know this.
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The one I saw had a choke about the size of a bagel.
--Ethan
The one I saw had a choke about the size of a bagel.
--Ethan
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