Pulse Width Modulation Power Supplies

Quint
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Pulse Width Modulation Power Supplies Dec 16, 2018 8:42:33 GMT -6 via mobile Martin John Butler likes this

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Post by Quint on Dec 16, 2018 8:42:33 GMT -6

So I'm nearly done with a pretty major studio upgrade and, among other things, have some new ventilation lines which I've installed. I've been researching inline fans to pull air through the system and came across this:

www.acinfinity.com/component-cooling/inline-duct-fan-systems/cloudline-s8-quiet-inline-duct-fan-system-with-speed-controller-8-inch/

I'm interested in it because these Cloudline fans seem to be very quiet compared to a lot of the competition, as far as blade noise goes. However, it says that these fans use Pulse Width Modulation (PWM) in their power supplies which, as I understand it, is a type of switching supply, and has me wondering if this might not introduce electrical noise into the circuit similar in nature to how some dimmer switches can introduce noise into the connected circuit.

Does anybody have any experience with PWM power supplies? On one hand, it's not like I don't have other gear with switching supplies, so it's not like I'm not already maybe a little "compromised" as far as noise being introduced into my electrical by a few switching supplies in my studio. I just don't want to make things obviously worse with my fan choice. I know that I've always heard about certain dimmer switches being a really bad idea because of how much noise they introduce, so this PWM supply got me thinking about that and whether or not I might be similarly introducing an electrical noise problem with this fan.

Thoughts?

keymod
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Pulse Width Modulation Power Supplies Dec 16, 2018 10:36:30 GMT -6

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Post by keymod on Dec 16, 2018 10:36:30 GMT -6

I would think that if this were plugged into an outlet with a dedicated circuit, or sharing a lighting circuit which is not part of your audio circuitry, that there should not be any problem. Ideally, lighting and peripheral circuits should be on opposite phase of audio circuits. And, of course, everything must be properly earthed.

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johneppstein
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Pulse Width Modulation Power Supplies Dec 16, 2018 11:39:05 GMT -6 keymod and iamasound like this

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Post by johneppstein on Dec 16, 2018 11:39:05 GMT -6

Dec 16, 2018 10:36:30 GMT -6 keymod said:

I would think that if this were plugged into an outlet with a dedicated circuit, or sharing a lighting circuit which is not part of your audio circuitry, that there should not be any problem. Ideally, lighting and peripheral circuits should be on opposite phase of audio circuits. And, of course, everything must be properly earthed.

Not really. A dedicated circuit probably wouldn't help, as switching supplies can radiate RFI through the air, not the power line, just like cheap lighting dimmers.

Note the use of the word can. As with many such things, the devil is in the details. If the supply is correctly deasigned with RFI suppression circuitry there's no problem, However if the manufacturer cheaps out and skimps on the suppression circuitry then you can have a real noise problem. Unfortunately the only way to be certain is by actually testing the supply in use as there are no recognized rating systems that I've ever heard of. There's a similar problem with LED light bulbs, which also contain small switching supplies.

You should still follow good practice in assigning functions to different phases, of course.

Last Edit: Dec 16, 2018 11:39:45 GMT -6 by johneppstein

Quint
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Pulse Width Modulation Power Supplies Dec 17, 2018 8:54:54 GMT -6 via mobile

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Post by Quint on Dec 17, 2018 8:54:54 GMT -6

So circuits for all of my gear are/will be on a separate phase from lighting, fans, etc.

My specific question about PWM is whether or not it introduces noise at a much higher level than the switching supply you might find in something like say a computer?

I can live with that sort of noise because, hey, I need a computer to record and, thus far, I haven't actually had any practical issues with electrical noise introduced by my PC.

I just don't want to introduce something that intrinsically produces a much worse degree of noise, such as that which we've heard about with dimmers. I've never dealt with PWM power supplies before, so I figured I should ask.

ericn
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Pulse Width Modulation Power Supplies Dec 17, 2018 9:55:04 GMT -6 via mobile

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Post by ericn on Dec 17, 2018 9:55:04 GMT -6

Dec 17, 2018 8:54:54 GMT -6 Quint said:

So circuits for all of my gear are/will be on a separate phase from lighting, fans, etc.

My specific question about PWM is whether or not it introduces noise at a much higher level than the switching supply you might find in something like say a computer?

I can live with that sort of noise because, hey, I need a computer to record and, thus far, I haven't actually had any practical issues with electrical noise introduced by my PC.

I just don't want to introduce something that intrinsically produces a much worse degree of noise, such as that which we've heard about with dimmers. I've never dealt with PWM power supplies before, so I figured I should ask.

That’s the thing, it’s all about how it’s implemented so nobody can say for sure one way or the other.

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Quint
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Pulse Width Modulation Power Supplies Dec 17, 2018 11:33:38 GMT -6 via mobile

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Post by Quint on Dec 17, 2018 11:33:38 GMT -6

Dec 17, 2018 9:55:04 GMT -6 ericn said:

Dec 17, 2018 8:54:54 GMT -6 Quint said:

So circuits for all of my gear are/will be on a separate phase from lighting, fans, etc.

My specific question about PWM is whether or not it introduces noise at a much higher level than the switching supply you might find in something like say a computer?

I can live with that sort of noise because, hey, I need a computer to record and, thus far, I haven't actually had any practical issues with electrical noise introduced by my PC.

I just don't want to introduce something that intrinsically produces a much worse degree of noise, such as that which we've heard about with dimmers. I've never dealt with PWM power supplies before, so I figured I should ask.

That’s the thing, it’s all about how it’s implemented so nobody can say for sure one way or the other.

If so, then I'm fine with trying it out to see how it goes. I was just making sure there wasn't some sort of obvious "no no", where using a PWM would be a nonstarter.

I'll order one and see how it goes.

Last Edit: Dec 17, 2018 11:34:38 GMT -6 by Quint