jkowtko
Well-Known Member
There have been a couple instances where cheap electrical props used in our performances induced a buzz in the audio when they are faded up or down.
One of these was a cheap $10 fire unit with a small light and a fan that blows a piece of silk upwards like a flame. The transformer might be a diode(?) transformer, evidently very cheap. Interestingly, two of the four units induced the buzz, and two (purchased earlier in the year) did not.
The second is an old tube TV set being used on stage and is being powered up and down during a scene. When it turns off we get a series of static pops through the PA.
Neither of these devices had a ground wire.
The lighting guy and I haven't had a chance to research this yet -- so we're not sure how a small device like this attached to a different 100amp circuit from the sound circuits is getting into the audio.
If you know what this is and can explain briefly and/or point me to some literature, I would appreciate it. I would like to understand what's going on so we can plan appropriately for these issues in the future when props like this are needed on stage. It's not hugely disruptive to the performances but nontheless I'd like to resolve them whenever possible without having to pull a prop.
Thanks. John
One of these was a cheap $10 fire unit with a small light and a fan that blows a piece of silk upwards like a flame. The transformer might be a diode(?) transformer, evidently very cheap. Interestingly, two of the four units induced the buzz, and two (purchased earlier in the year) did not.
The second is an old tube TV set being used on stage and is being powered up and down during a scene. When it turns off we get a series of static pops through the PA.
Neither of these devices had a ground wire.
The lighting guy and I haven't had a chance to research this yet -- so we're not sure how a small device like this attached to a different 100amp circuit from the sound circuits is getting into the audio.
If you know what this is and can explain briefly and/or point me to some literature, I would appreciate it. I would like to understand what's going on so we can plan appropriately for these issues in the future when props like this are needed on stage. It's not hugely disruptive to the performances but nontheless I'd like to resolve them whenever possible without having to pull a prop.
Thanks. John