Hi folks,

I just bought a 4x55w fluorescent lamp fixture. It's not a Kino Flo, it's a cheaper make and model. My unit was an ex-display unit. The dimmable ballast is built into the lamp fixture.

The problem is that the lamp is really noisy! It sounds like a distorted mains hum. The sound varies depending on the setting of the dimmer. In general, the noise gets more intense the dimmer the lamp is. I've tried re-seating the tubes and I've also tried gently knocking the lamp fixture (!) but the noise wont go away. I've also tried leaving the lamp to fully warm up but that doesn't help.

I'm just wondering if anyone else has experienced this problem? Is there an easy fix? (Like perhaps the tubes are old and need to be replaced?)

In the past, I have experimented with building my own fluorescent lamp fixtures. I found that some ballasts are noisy and some ballasts are silent. I will phone the company who sold the lamp to me on Monday to ask if they'll replace the lamp. But I'm also considering opening the unit up, removing the existing ballast and installing a couple of dimmable Philips ballasts which I know are silent-running. Even after buying the new ballasts, the lamp will still have cost me less than half the price of an equivalent Kino Flo!

Call the company first because you will not get any help from them if you modify the unit before they have a chance to fix or comment on the problem

sure thing.

If it's a professional fluorescent light, ie., one designed for shooting, it will have a silent electronic ballast. The ones you buy for household lighting may have electronic ballasts but in most cases they make some noise. One reason professional ones cost more. I've never used lights with dimmers, but I guess it could be the dimmer as well. Or even a defective lamp. Probably the easiest thing to do would be to take out one lamp at a time, then put each one back in one at a time, ie., check out each one to see if there's one that doesn't hum. If so, that might tell you if the lamp is the problem. Or buy a new lamp and try it out and if it hums, then it's probably the ballast or the dimmer. But if you just bought the light, the above comment is best--call the company first. If it's making noise they should replace it.

Hmm. i thought the hum from fluoros was always the ballast. Not sure where i heard that, but come to think of it we had humming fixtures at my old work that changing the bulbs out did nothing... which I *think* validates the theory.

It's almost always the ballast, but I remember on some house lights in a studio there was a humming bulb that was about ready to die. I took it out and the hum stopped. It's different from the ballast noise. Supposedly electronic ballasts don't make noise, but that's not always true for non-movie lights.

A defective (or cheap for that matter) electronic fluorescent ballast can indeed make a hum. It all has to do with the grade of transformer they used inside the ballast. Its pretty rare on ones that are selected for studio/pro lighting fixtures but could happen if the transformer inside the ballast developed a problem of some sort or the transformer was just super cheap. I would think if the model in question is still in warranty, you should be able to get it replaced. That should be a simple ballast swap.