MH Bulb hums

[nazzman]

Recently replaced a 250w de MH bulb with new Phoenix bulb. The bulb started humming as usual on start up but never stopped . I put my old bulb back in and it doesn't hum is it the new bulb or is it my ballast?

 

[Reefing Madness]

Im thinkin the ballast.

 

[beadlocked450r]

How old is the bulb? I had new bulbs work when i tested them and then when the lights came on the next day by the timer they wouldn't fire. My old bulbs did fire,so i had the bulbs returned and they shipped me new bulbs free of charge.

 

[nazzman]

The bulb is new out of box

 

[beadlocked450r]

And if you put old bulb in no noise? I would say bulb

 

[Reefing Madness]

New bulb if firing differently that the old ones, therefore the hum, you using magnetic ballasts?