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Electrical Interference From A Dimmer?

Discussion in 'Amps and Cabs [BG]' started by Zooberwerx, Apr 4, 2006.


  1. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Anybody experience this or am I going nuts?

    I noticed a pronounced electrical buzz from my Yorkie XM 200 combo which I had not heard previously. I ruled out my bass, cable, etc. and started looking for household sources that might be responsible. I recently installed a halogen light fixture in the kitchen controlled by a slide type dimmer. I found that when the light fixture is run at about 50%, the "bzzzz" becomes quite evident but disappears when the light is switched off completely.

    Any comments / suggestions?

    Riis
     
  2. This is perfectly normal. Household dimmers typically use triacs to chop up the AC signal. These inject a pile of hash onto the line and can cause interference with devices on the same circuit or within close proximity to the dimmer.
     
  3. If you want to hear something nasty, play an AM radio near a dimmer and turn down the brightness on the lights being controlled. NOISE!!!!

    Paul Mac
     
  4. Kael

    Kael

    Dec 26, 2004
    Oklahoma City
    Dimmers are evil. They make bad stuff happen with amps.
     
  5. Imagine that dimmer on steroids and multiplied by like 500-1000 and you've got yourself a stadium sized hum generating monster. Used to be the bain of my existence when I was a lighting operator.
     
  6. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    UNFILTERED thyristor dimmers are evil. Pretty much all the current stage dimmers out there these days are SCR or Triac based - the same as the one in your house. The difference is the home dimmers are el-cheapo, and not filtered, and theatrical dimmers are, and hence, don't have the problems (at least not the good ones, anyway . . . ) And triac or SCR makes no differenct - a triac is just a single package with effectively two back to back SCRs in it.

    - Tim
     
  7. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Guess I'll be installing a filtered thyristor dimmer (if I can find one). The house itself is 50+ years old and only a portion of the electrical package has been updated.

    Not that it matters, but the lamp really looks nice!

    Riis
     
  8. Lonnybass

    Lonnybass Supporting Member

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    Try to find an electrical outlet on another circuit close to where your amp is set up that you can plug it into. This may help minimize much of the noise.

    Lonnybass
     
  9. Joe P

    Joe P

    Jul 15, 2004
    Milwaukee, WI
    Just do what the studios do!

    A recording studio doesn't want an SCR within miles. They use VARIACS!

    http://www.inotek.com/Catalog/technipower1pc.html

    Joe
     
  10. arizonabass

    arizonabass

    Feb 6, 2002
    Tucson, AZ
    Look for a good quality Lutron dimmer that is sold for around $15 - 18. They do have RFI suppression circuitry; I had some cheap dimmers that wreaked havoc with a portable AM radio (at least). I replaced them with the Lutron ones, and these Lutrons produce little if any noise at all, depending upon where in their "sliding travel" they are set.
     
  11. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    There are not too many to find in the home stuff - your best bet would be to look at commercial stuff, but it will cost you. The filters in theatrical dimmers are typically large iron core chokes, which are much larger than the power section of the dimmer itself. Sometimes, it is just easier to put a line filter on the equipment that is getting the noise, and those are not too expensive.

    - Tim
     
  12. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Line filter, huh? Any recommendations as to brand or source?

    Thanks

    Riis
     
  13. Interceptor

    Interceptor Supporting Member

    Mar 29, 2005
    Madison, WI
    +1 for the Lutron solution. I learned about them through the ham radio community, things that cause RF noise drive that gang crazy. I had the same problem in my home, replaced the dimmers with Lutrons, buzz be gone. I don't know if the big home improvement chains stock Lutron, but they are worth the hunt.
     
  14. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Nothing in particular, but I have seen inline filters at a lot of electronic component/computer supply places. I have a 20 amp unit on my bass gear, made by Datashield. It is about 7x4x3 inches, on the end of a cord. Weighs several pounds - good filters are not typically that light . . . .

    - Tim
     
  15. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Nothing in particular, but I have seen inline filters at a lot of electronic component/computer supply places. I have a 20 amp unit on my bass gear, made by Datashield. It is about 7x4x3 inches, on the end of a cord. Weighs several pounds - good filters are not typically that light . . . . I ran one at one time on my home audio gear for exactly the reason you state, with total success. I then upgraded the shoddy component that was taking in the noise, and moved the filter on to bigger and better things. Oh, these units also typically do surge suppression and all that other good stuff too . . . not sure if any of the Furman stuff filters or not - it's a bit too $pendy for my tastes . . . .

    - Tim
     
  16. arizonabass

    arizonabass

    Feb 6, 2002
    Tucson, AZ
    I bought mine at Home Depot. The Lutron model I bought is "Skylark."
     
  17. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    A studio I helped construct in the early 80s used variacs for the studio and control room lighting. That was an idea I'd learned from a radio station built by a friend of mine. They are quiet, but they do get warm. We mounted them on anodized aluminum plates to help dissipate the heat, but it still freaked some people out when they reached to turn the lights up or down and felt a toasty warm metal wall panel under the knobs.
     

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