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-   -   DC Offset, and Dimmer switches with LED lights. (https://www.audioaficionado.org/showthread.php?t=43860)

Mouse 09-20-2018 02:53 PM

DC Offset, and Dimmer switches with LED lights.
 
My MC has a hum, a hum caused by DC offset. I had an electrician come by as a recommendation from MC to troubleshoot the amp humming. While there may be a quiet hiss coming from the speakers, I can hear some noise generated by the amp itself. That noise is allegedly caused by DC power on an AC line. DC doesn't belong on an AC line, and it baffles an electrician because it's not supposed to happen. That's not the way electricity works. :no: Anyway after convincing the electrician to put his multimeter on and check, we find DC on the AC line. It almost doesn't matter because we can't locate it's source. It could be anything in the whole home.

Anyway I got some new expensive high CRI LED lights. They hum loud. I swap my old dimmer switches for the LED compatible dimmer switches and it's just as loud. We tested them all for DC offset. Sure enough ALL old style and ALL new LED/CFL style dimmers all have some DC offset when tested with a multimeter. I even tested multiple brands. LED hum went away with the DC offset when I scrapped the dimmers for a standard switch. Now that I know every dimmer is a source for DC offset, I'll be pulling dimmer switches from my entire home. I yanked out 5 already, and that's just the kitchen and halls. Next stop is the listening/movie room. Anyone know of a dimmer switch guaranteed not to have a DC offset and noise? I liked having a dimmer.

Masterlu 09-20-2018 02:59 PM

Emotiva makes a unit that effectively removes all DC voltage from the AC line.

https://www.amazon.com/Emotiva-CMX-2...aui_i_r_o0_img

kubla36 09-20-2018 09:32 PM

Hmmm... I’ve got a lot of aware dimmers.

https://www.psaudio.com/podcast/dc-blockers/

AudioGremlin 09-21-2018 05:54 AM

Not only dimmers, some appliances using half-wave rectification cause DC problems too.

Mouse 09-21-2018 11:15 AM

Quote:

Originally Posted by Masterlu (Post 932392)
Emotiva makes a unit that effectively removes all DC voltage from the AC line.

https://www.amazon.com/Emotiva-CMX-2...aui_i_r_o0_img

I ordered one, thanks Ivan.
I'm disappointed that my evo3 sigmas doesn't filter it for me, but I'll be sure my next power filter tackles DC. The Emotiva model is cheap enough for proof of concept.

richardallred 09-21-2018 01:39 PM

Is dc a factor if your using a p10?

kubla36 09-21-2018 09:09 PM

DC Offset, and Dimmer switches with LED lights.
 
Quote:

Originally Posted by richardallred (Post 932505)
Is dc a factor if your using a p10?


According to the podcast, they filter DC in all their regenerators.

richardallred 09-21-2018 09:37 PM

Thanks

mcpaf76 09-21-2018 10:32 PM

I have about 10 Lutron Casetas and have zero humming from any of my LEDs which are basically 100% of my house, and neither of my 2 amps, including 1 MA252, which has zero power conditioning and a stock cord right now, dead silent. They're not cheap, about 60 dollars a piece. Maybe these will help?

Mouse 09-22-2018 12:29 AM

Quote:

Originally Posted by mcpaf76 (Post 932561)
I have about 10 Lutron Casetas and have zero humming from any of my LEDs which are basically 100% of my house, and neither of my 2 amps, including 1 MA252, which has zero power conditioning and a stock cord right now, dead silent. They're not cheap, about 60 dollars a piece. Maybe these will help?

It's worth a shot.


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