pop over main caused by a fan?

[Destrox]

I'm in the middle of an assembly in our theater. Since I'm bored in the booth, I started turning the small desk fan that we have next to the sound board on and off. I started to notice whenever I turn it on or off, there is a small pop over the main speakers. I listened to the individual mic and the main using headphones and the pop is not coming from the board. There's also no talkback mic left on (unplugged it to make sure). We're using a LS9 if that makes any difference. This has happened once or twice before. Anyone know what's causing this and how to fix it?

[Footer]

Odds are your amps and the fan are on the same circuit. Motors can cause a lot of noise on a line. For that matter it could be anything audio related that is on the same circuit, such as EQ's, compressors, CD player, whatever. Stop messing with it and put it on another circuit. Also, a power conditioner will help clean up the power.

[Destrox]

Once I realized it was the fan making the pop, I stopped. The amps are in the prop lofts back stage so would it make that much of interference to cause that?

[Stookeybrd]

Regarding your question: Yes, the fan can make that much interference. What Kyle is saying is that regardless of location, if the amps and fan are plugged into the same circuit than the noise will appear.

You can test this (with the system off) by finding what circuit the amps are plugged into and flip that breaker and see if the fan turns on. If it won't turn on, they are on the same circuit, if not... it gets interesting.


Good Luck!
Cameron Stuckey

[Footer]

Originally Posted by Stookeybrd

You can test this (with the system off) by finding what circuit the amps are plugged into and flip that breaker and see if the fan turns on. If it won't turn on, they are on the same circuit, if not... it gets interesting.

It could be anything audio related plugged into the circuit. Does not have to be the amps. Cheaply made motors can cause all kinds of noise on the line.

[Les]

Is it plugged into an orange receptacle? If so, that receptacle is "clean power" designated for sound equipment only.

[museav]

Originally Posted by Les

Is it plugged into an orange receptacle? If so, that receptacle is "clean power" designated for sound equipment only.

It may mean that for your facility but that is not true in general. An orange receptacle used to indicate that it was an isolated ground receptacle but even that has changed and now an IG receptacle will have an orange equilateral triangle on it. Even if it is an isolated ground receptacle, and many isolated ground systems are not properly maintained all the way back to the service entrance panel, that alone does not necessarily mean that it is "clean power" or derived power or dedicated for the sound system or on a particular phase or anything else.

If the amps are at the stage and the fan is in the booth, I sort of doubt they are on the same circuit. They could be but they more likely might be on the same phase of the same panel. That's why I prefer to keep fans, pumps compressors (including fridges and water coolers), copiers, etc. off of the same phase and panel as the audio and video systems power.

[Les]

Originally Posted by museav

It may mean that for your facility but that is not true in general. An orange receptacle used to indicate that it was an isolated ground receptacle but even that has changed and now an IG receptacle will have an orange equilateral triangle on it. Even if it is an isolated ground receptacle, and many isolated ground systems are not properly maintained all the way back to the service entrance panel, that alone does not necessarily mean that it is "clean power" or derived power or dedicated for the sound system or on a particular phase or anything else.

If the amps are at the stage and the fan is in the booth, I sort of doubt they are on the same circuit. They could be but they more likely might be on the same phase of the same panel. That's why I prefer to keep fans, pumps compressors (including fridges and water coolers), copiers, etc. off of the same phase and panel as the audio and video systems power.

Actually, I don't have a "home" facility. But in any event, I try to avoid plugging non-sound equipment into orange receptacles :-)

[TimmyP1955]

Wire a .01/600V cap across the terminals of the switch in the fan. This may eliminate the pop.

[Destrox]

It's plugged in just a normal power outlet. I don't think they are on the same breaker, but I'll try to figure it out. It's plugged into the same outlet as our electronic bell system (those speakers are automatically turned off when not in use) so it might mess those up a little if we turn off the power. And I'd rather not have to buy something to fix it since it's not too noticeable.