# Light Switch and Speaker "Pop"



## roadtonowhere08

Hey Guys,

 I moved my stuff downstairs and I have run into an interesting problem that I have never heard about before. When someone turns on or off the light in the room adjacent to the room I have my stuff plugged into, the speakers make a single pop that is not loud but noticeable. It sounds like the pops on an LP. I am assuming that the switch is causing a surge or spike of AC, but I am not sure.

 My setup is a computer with a coax out to a Benchmark DAC1 into a Face Audio power amp. The computer, DAC, and amp are plugged into a Brickwall surge filter (PW8R15AUD), and thus into the same wall outlet. 

 I want to know a few things:

 1. What is causing this pop, when upstairs, I had no problems?
 2. Is this pop damaging to the DAC or amp?
 3. How can I get rid of this?

 Thanks in advance for any help...


----------



## Listens2tubes

First thing I'd suspect is the light bulb the switch is controlling? I had a flourecent bulb over my turntable that made a thud in the subwoofer of our home theater system 2 rooms away when I switched it off, changing to a standard filament bulb solved that one. If that's not it try the switch. You can replace it fairly cheaply. Of coarse be sure the power is off when replacing the switch.


----------



## oicdn

It's the way the circuits are laid in your house. It's kinda like the reason you don't want too many things in the garage (typically speaking) running at once because likely the washer and dryer are on the same circuit as all the outlets in the garage, and sometimes the adjoining rooms.

 So sometimes you'll get a pop because of the increased/decreased load on that particular circuit. I have no idea how harmful it is to the equipment, but I'm a little anal when it comes to things of that nature to begin with.


----------



## G-man

a surge protector (or whatever those plug strip things are called) may stop them.


----------



## infinitesymphony

Isolation transformer, maybe, but a power conditioner or regenerator may work better if you're having power sags and you can't run a dedicated circuit to your audio room.


----------



## dvessel

Stick your ear to the switch and turn it on and off. It could be a crappy switch that sparks. If you don't notice anything, then flip it slowly. Random guess but I've heard sparking before with cheap switches. Could cause interference.


----------



## Sovkiller

Replace the switch, it is making an small arch inside...also consider placing an small filter across the legs of the switch, similar to the ones used in vintage amps switches, that will avoid the on and off to be instant, as the small filter will hold a little charge that will gradually be released, and avoid the arch inside the switch...


----------



## Mike Wazowski

OP and others:
 I was just on the phone with a PS Audio tech, asking him this very question (did not know of this thread)! What he told me is that _none_ of their products will "filter" such pop - not even the $2K+ Power Plant, which is a regenerator! As oicdn said, this is due to the wiring of the house. There are two remedies: (1) make a dedicated circuit for your audio system only, going directly to the switch box; (2) avoid flipping switches when you are listening to your setup. I doubt if there is any serious harm made but agree this is annoying and somewhat alarming.


----------



## Uncle Erik

It's probably a quick pulse of RFI from the switch. The earliest transmitters were spark-gap transmitters, which produce a wave of RF across a pretty broad part of the spectrum. Which is why they're not much used today since you have a tough time confining them to one frequency.

 So what's likely happening is that the switch makes a spark, sending radio waves out (RFI) that your equipment picks up like an antenna and translates into a pop. Which is why all the line filters, power regenerators, etc., etc., don't help.

 You could try replacing the switch with a newer one. That might stop it. You could use shielded cables, which might work. You can rearrange your gear, sometimes that helps. Or, God help us, try some ERS paper. 
	

	
	
		
		

		
			





. Yeah, it works. Edit: try a metal switch plate cover, and ground the cover. Should work as long as your J-box is metal.

 Keep in mind that RFI is a tricky gremlin. There isn't one way to stop it that works for everyone. You usually have to hack around until you find the answer. Remember that it comes as radio waves, not something mysterious through the power jack.


----------



## Mike Wazowski

Hmmm... I'll save this your post, thanks. Interesting... Does not seem a priority right now - I just realized that I was switching that bedside lamp while listening to my new Marantz SA8001, a few times, and nothing happened. So this might be just a particular lamp in my case, the one on the desk, which has this tiny high intensity bulb, and lots of metal. There was always a fairly loud pop when I was turning that one on/off while listening to $50 Logitech computer speakers. I don't feel like trying to see whether this repeats with my new CDP & amp 
	

	
	
		
		

		
		
	


	




 ...

 PS Audio tech told me that in case of switching the lamp, the interference that occurs is "low frequency, high amplitude", while their devices filter out the high frequency AC noise... I must say I've got somewhat mixed impression of PS Audio. They sure take this whole power/AC noise thing very seriously, tons of interesting reading on their site. Yet there is a heavy flavor of commercial interest; another thing they seem to be taking very seriously is marketing. They make these Youtube infomercials... What has put me off the most is that you read their manual to, say, a $300 Duet, and all along they try to scare you into buying _all_ their power product line - you should not only add their power cable, but also their wall outlet, and even feed this Duet from their $2K+ Power Plant regenerator... Ridiculous.


----------



## zowie

I have power sags when my central AC cycles on. All the lights dim. Don't know if I should do anything about it.

 Aslo, what do people think about dimmer switches -- should I replace them with regular on/off?


----------

