Why does dimmed lighting sometimes hum, and how can it be corrected?
Why does dimmed lighting sometimes hum, and how can it be corrected?
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
How can I avoid the buzzing the dimmers cause to my sound system ?
There are numerous ways that dimmer noise can get into audio systems and it's largely trial and error in determining what in particular is causing your problem and hence how to fix it. The principle ways are either back up the mains or induced into your audio equipment or cables.
What you hear typically in audio system is common mode noise on the hot and neutral, the spike of turn-on of the scr. The higher the rise time of the current in the dimmer, more noise is sent to the mains wiring. So well filtered dimmer will generate less noise problems.
Reduce the possibility of it coming up the mains by taking a totally separate mains supply from the lighting, if possible get a totally separate power socket (or sockets) run in for sound from wherever the electricity board intake is. If this is not possible, then an isolation transformer stops quite much of the noise on the secondary side (better with shield between coils). So put the sound system on the isolation transformer and tie to earth (ground) almost no problems. This assume that sound wiring is correct, especially shielding is done well and ground loop are avoided.
To reduce the possibility of interference induced to the audio cables, run all non speaker level audio cables as balanced lines (or certainly all of any length). You might have to buy balancing transformers if your kit isn't balanced already. Also keep them as far away physically from any lighting cable runs as you can. Make sure that your system does hot have any harmful ground loops. Make sure none of your audio kit is anywhere near the dimmer racks.
Because of the way all dimmers deliver power at settings other than full brightness, the filaments inside a light bulb may vibrate when lighting is dimmed. This filament vibration causes the hum. To silence the fixture, a slight change in the brightness setting will usually eliminate bulb noise. The most effective way to quiet the fixture is to replace the light bulb.
How can I avoid the buzzing the dimmers cause to my sound system ?
There are numerous ways that dimmer noise can get into audio systems and it's largely trial and error in determining what in particular is causing your problem and hence how to fix it. The principle ways are either back up the mains or induced into your audio equipment or cables.
What you hear typically in audio system is common mode noise on the hot and neutral, the spike of turn-on of the scr. The higher the rise time of the current in the dimmer, more noise is sent to the mains wiring. So well filtered dimmer will generate less noise problems.
Reduce the possibility of it coming up the mains by taking a totally separate mains supply from the lighting, if possible get a totally separate power socket (or sockets) run in for sound from wherever the electricity board intake is. If this is not possible, then an isolation transformer stops quite much of the noise on the secondary side (better with shield between coils). So put the sound system on the isolation transformer and tie to earth (ground) almost no problems. This assume that sound wiring is correct, especially shielding is done well and ground loop are avoided.
To reduce the possibility of interference induced to the audio cables, run all non speaker level audio cables as balanced lines (or certainly all of any length). You might have to buy balancing transformers if your kit isn't balanced already. Also keep them as far away physically from any lighting cable runs as you can. Make sure that your system does hot have any harmful ground loops. Make sure none of your audio kit is anywhere near the dimmer racks.
BCD Electric RSS feed