I replaced an existing candelabra type fixture with a new chandelier that uses 6 standard base 60 watt bulbs mounted with the light bulb bases up. After I restored the power the existing dimmer would hum when I dimmed the lights. The dimmer never had this problem with the old style fixture and lamps. The new lamps total 360 watts on a 600 watt dimmer. I replaced the dimmer twice, with two different Levaton dimmers and still have the same problem. The lighting store that sold the chandelier said it is the bulbs but that they did not know what type would fix the problem. The Light Bulb Co said that it was the dimmer. Any ideas?