do light dimmers always cause electrical hum?

  • Thread starter Thread starter arcadeko
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arcadeko

arcadeko

Illuminatius Overlordious
I am wiring track lights in my new space, I wanted to use a dimmer switch.

However, in the room I am in now, the light has a dimmer and if it is on, it causes a terrible hum in my monitors. Now this could be due to a bad ground or something in that circuit, and the outlet might be in that same circuit.

Does anyone here use a dimmer in the studio without problems? I wired in a dimmer I found but it's broken. Before I go buy another one I wanted to see if it was even worth trying...
 
A dimmer with a shield will not cause a hum. You probably are on the same circuit and this can be part of your problem. Dimmers with isolation and shielding are standard issue at your local electrical supply houses but are quite expensive. If you can remove the lights from your power circuit and get them on the OPPOSITE phase you'll go far to eliminating the problem.
 
cavedog101 said:
A dimmer with a shield will not cause a hum. You probably are on the same circuit and this can be part of your problem. Dimmers with isolation and shielding are standard issue at your local electrical supply houses but are quite expensive. If you can remove the lights from your power circuit and get them on the OPPOSITE phase you'll go far to eliminating the problem.
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I will have to ask an electrician cause IDK anything about getting opposite phase? How expensive is quite expensive? Does Home Depot have them? like $30 expensive or like $100 expensive?
 
Ask your electrician but very few domestic properties have more than a single phase available anyway. Well, at least that's true in the UK and Australia--can't speak for the USA or "Another Dimension", but I very much doubt many houses or apartments have 3 phase power.
 
I am an electrician. A Master. Been one for almost 35 years. I'm not talking 3-phase or any such thing. Every "single-phase" service has two hot legs and therefore it has TWO phases. To keep the dimmer from making noise in your recording system, it needs to be on the opposite phase of the power as the receptacles in the room you're working in. Rotary dimmers and common household types of dimmers have a wiper much like the ones found in a volume control on an amp. This creates a field which recording equipment is sensitive to. An electronic dimmer may work for your purpose but at $30 plus.

You need to determine what is on the circuit you are using in your studio. A simple flipping of the breakers one at a time and then notating what is off in the process should give you a good idea.

Whatever you find, a $5 dimmer will not do the job. Another thing to consider is the load. Each lamp you add to the track lighting will increase the load on that particular circuit, and if this circuit and the one feeding your plugs are one and the same, you decrease the circuits ability to handle amps,screens,computers,outboard, etc etc.....
 
Ah, okay...you're talking about that peculiar American system with a single split phase so you can provide 220/240V to things like stoves and dryers. In the parts of the world with 220/240V as the standard mains voltage, the choice is single phase (small/domestic users) or three phase which is common in large and commercial users.

Thanks for clearing that up--my only involvement with US power standards has been in commercial facilities with 3 phase and neutral. This could explain the number of people with hum and buzz problems posting on this forum.
 
I'll leave Cavedog to give the details but different circuits and different phases are not necessarily the same thing. I'm sure it's pretty common to have lighting and power sockets on different breakers but fed from the same supply.
 
Well - unfortunately my lights ARE on the same circuit as my outlets... however - I went a picked up a dimmer for like $18 at home depot (Not the cheapest, almost the most expensive) and tried it out. So far no hum/buzz so it looks good so far.

But - I have only hooked up the interface and monitors and played back some mp3's to test it - haven't got all the gear hooked up so can't record yet but it looks good so far. Upstairs the buzz as soon as the light comes on.

Thanks for all the in depth help! I will be posting photos of the new studio this week. This weekend I build bass traps. woohoo!
 
Dude, you don't want dimmers on your circuit, but whatever. Hope it works out. I have been doing electrical work ever since I was a kid. If you have trouble PM me.
 
The dimmer in my circuit comes of a Y that is after my outlets. It doesn't cause any noise what-so-ever - so is there still a reason to not use a dimmer?
 
arcadeko said:
The dimmer in my circuit comes of a Y that is after my outlets. It doesn't cause any noise what-so-ever - so is there still a reason to not use a dimmer?
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I'd say no...if you're doing it and it's trouble free then no problem.

My guess is that the blanket suggestion no to stems from the fact that it IS a common cause of audible problems and these can be hard to cure if you're unlucky. However, consider every concert you go to or every TV studio you've seen programmes from--all those have LOTS of dimmers and, so long as the wiring is handled properly, they don't cause problems.

Domestic wiring, particularly in the USA from what I'm reading, can be somewhat unpredictable but, as I said, if you're lucky enough not to have problems then you're fine.
 
Sometimes you get lucky, sometimes you get screwed. Avoid dimmers, unless you KNOW the dimmer is a shielded design.

Ever notice that your circuit breaker panel has breakers on two sides? Well, your power line from the telephone pole gives you two 120 VAC leads, in opposing phases. When you bring it into the panel, one 120VAC line goes to one side, the other to... um.... the other. yeah, it's that simple.

But when you need 240VAC, you're wiring those two leads together to sum the voltage together.

So the concept of putting your dimmed lights on another phase means, your recording gear on a circuit breaker on one side of the control panel, and your dimmer controlled lights on another circuit breaker on the other side of the control panel. So not only are your gear and lights on separate breakers, but now they're on separate phases of your incoming power.

Yes, gutting your house and running dedicated wiring and outlets and all that is a pain in the ass.

But if you want professional results, you need professional foundations.
 
couldn't you just sheild the thing?
I'm asking 'cause I'm curious.
Since the dimmer gives off a field, couldn't you simply mount it inside a grounded metal box to shield it just like you would shield a guitar cavity?
 
Install a dimmer and if it makes noise, replace it with a switch.
 
Bobbsy said:
However, consider every concert you go to or every TV studio you've seen programmes from--all those have LOTS of dimmers and, so long as the wiring is handled properly, they don't cause problems.
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Very true, however the way they do this is to use extremely well designed industrial dimmer units designed for the entertainment industry with the dimmers located away from the audio and video equipment in a remote location running from a different power supply (even isolated) than the audio and video.

I have seen a show home that had lighting dimmers in every room and they located the dimmers in the underground garage and all dimming was dome by remote controls, this would more then likely give noise free dimming on audio.

The problem you have in studios is that at some point a guitar player with a single pole pick up will turn up and become a receiver of dimmer buzz.

I used to work in the live sound industry for years and dimmer noise was often an issue, we would set up at one venue with no problems, the next night at a different venue with the exact same set up buzz on every guitar rig, followed by us moving the dimmer, trying different power points, etc etc.

My advice is to forget the dimmer. Why not wire the lighting so that one or 2 globes are on one switch, and a globe or 2 is on another switch, if it's too bright turn off one the switches and reduce the number of globes. By doing this you can have a large number of low light globes that can be turned on and off to adjust the lighting mood.

Alan.
 
There are several ways dimmers can cause audio problems. The cheap ones in plastic boxes can radiate an EM field which can be picked up, particularly by unbalanced wiring. Modern theatre and TV dimmers are actually silicon controlled rectifiers which "chop" the electrical sine wave and can put a nasty buzz back into the electric mains.

And, finally, badly made or under-specced domestic dimmers can actually have a mechanical buzz which can be picked up by sensitive mics.

So, I generally agree with the advice about avoiding dimmers. However, since Arcadeko has installed them and been lucky, there's no reason I can think of to remove them again. He's either bought the right dimmers or his house is wired well...or both.

If I was going to put dimmers in my studio, I think I'd probably go for 12 volt track lighting and locate the actual transformer box and dimmer away from the studio, just putting the control in the studio.
 
Bobbsy said:
And, finally, badly made or under-specced domestic dimmers can actually have a mechanical buzz which can be picked up by sensitive mics.
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I have also heard humming coming from the incandescent filaments in the bulbs on low dimmer settings.
 
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