Can fluorescent lighting cause audio dropout? (1 Viewer)

[TonyTone]

I apologize if this isn't the correct forum to post this thread in, but I think that this may be the most appropriate one, plus it gets the most traffic in the H/W section so...
I have a simple H/T setup in the master bedroom; every once in a blue moon (well, not that infrequently) I'll get a very brief audio dropout whenever I'm watching a DVD movie. It rarely happens more than once during a viewing, lasts for no more than one second, and does not repeat itself in the same time position in the movie. Eventually, I had narrowed the cause to the fluorescent lighting in the master bathroom located adjacent to the bedroom; every time I flick the wall switch on while DVD movie audio dialog is taking place, I get the audio dropout. Dropout doesn't occur when I turn the fluorescent light off, and I mentioned DVD movie because no dropout occurs when audio source is non-digital, e.g., DBS via RCA audio cables.
I haven't had a chance to narrow it down further but I suspect the actual culprit is the cheap video cable I substituted because I didn't have a coax digital cable on hand at the time I set up my H/T equipment, and never got around to getting a "real" coax digital audio cable since it seemed that the audio was working for me all this time, other than the dropouts, which I assumed was perhaps a bad receiver or perhaps DVD player (both of which I'm not ruling out entirely).
I plan on swapping out the video cable for a dedicated coax digital audio one to see if it does the trick but I curious as to whether or not it's possible that a cheap video cable (essentially the cheapo patch cables that come with so many audio/video equipment) can pick up some sort of interference from fluorescent lighting (or at least when it initially turns on) due to the video cable possibly not rated at 75 ohms and/or being poorly shielded?
Thanks!

 

[John Garcia]

100% guarantee it is the flourescent lighting, but I don't think it will have anything to do with the type of cable used for coax digital (it's possible, but I doubt it).

Fluorescent ballasts are well known to be a potential cause of interference, most notably when they are turned on, when they are on the same circuit as your HT gear.

 

[Kevin T]

i don't have a flourescent fixture per se but i do have 4 flourescent mini-spiral bulbs in my living room fixture where my home theater is and i have had 0 problems with audio dropouts at any time.

kevin t

 

[John Garcia]

I have flourescent "bulbs" in basically every light in my house and I have no problem either. I am going to just guess that they use a different type of ballast, that is unlike the type used in a fixture type fluorescent, especially an older one.

 

[Seth_L]

Get a better cable. We had this problem at college when connecting our SB Live! cards to recievers. Both the fridge and the lights would cause drop-outs. We were running video cables for the signal. We replaced the cable with a 75 ohm video coax cables with screw on F connectors. And then use RCA to F connector adapters. The problem went away.

Seth

 

[TonyTone]

Some details, which may or may not be moot:
--The fluorescents in my bathroom are bulbs similar in size to the ones used to replace standard incandescent bulbs used in lamps, etc., but are of a different socket type (bulb has two small prongs on the end). I assume that there is a ballast since it takes a moment for the bulb to light up, plus I can hear the usual "ballast" noise befor the bulb lights up, unlike those "energy-saving" replacement fluorescent bulbs used in lamp fixtures, which don't have a ballast (AFAIK) in the usual sense--sorry, I'm not an electrician so I don't know the exact terms. As to what kind/type of ballast--like I said, I'm no electrician...
--My house is barely a year old so if it's an electrical issue, then I reckon it's either shoddy wiring or cheap electrical parts.
--As mentioned before, dropout occurs almost exclusively only when the ballast fires up (i.e., when I flick the wall switch to turn the fluorescent bulb on)--no dropout while (once) the bulb itself is lit. I say "almost" because every once in a blue moon I get a dropout when I flick the wall switch for the fluorescent bulb off, so there may be a possibility that the switch itself may be defective, although in what way I don't know since the bulb does turn on and off when I flick the switch.
Regardless, replacing the video cable substitute with a dedicated coax digital audio cable (RatShack gold series, if you must know) didn't resolve the problem. I'll replace the wall switch although my gut feeling is doing so won't eliminate the problem either.
Maybe it's the ballast, maybe not--I'm getting conflicting issues as to whether or not the fluorescents are the culprit since others have said that they haven't noticed any dropouts, although they haven't explicitly mentioned as to whether or not they had checked for dropout right when they flicked the switch, and that it appears that the bulbs in their case were the "drop-ins", not the ones that light up with the help of a separate ballast like typical fluorescent fixtures.
Anyone know for certain what could be causing my dropouts?
Thanks!

 

[AaronBatiuk]

replacing the video cable substitute with a dedicated coax digital audio cable (RatShack gold series, if you must know) didn't resolve the problem

Better yet, replace the Coax with a Toslink (fibre-optic) cable, if both the DVD and receiver have the capability. Toslink is immune to any kind of RFI/EMI interference, such as the stuff possibly being caused by your lighting. People blast toslink for many reasons (most of which are unjustified), but this immunity to noise is one of it's great strengths.

If you system is picking up interference from the power line rather than from the digital audio connection, then you will have to tackle it differently. If your systems is not plugged into a good power bar with EMI/RFI filtering, try doing that. Or try power line EMI chokes from radio shack for the DVD and receiver power cords.

Perhaps you could try a power line conditioner (not cheap).

 

[Seth_L]

Tony,

Try the "home made" digital coax cable method. Something like item 15-1547 (Radio Shack) and item 278-290 (Radio Shack). This worked when even expensive monster video cables did not.

Seth

 

[Jeff Kohn]

I used to have this problem with one of my HDTV cards in my HTPC. Whenever I turned the (fluorescent) kitchen light on, which was apparently on the same circuit, I'd get an audio drop-out. It only happened with the HDTV coax connection, the DVD audio used toslink and was not affected. I agree with the poster who said that toslink would solve the problem. I don't think it's shoddy wiring or the light switch, it's just the nature of fluorescent lighting; you were just unlucky enough to have it on the same circuit as you HT gear.

The strange thing is, I later upgraded to a different HDTV card, and even though it still had a coax connection, it didn't suffer from the drop-outs. This tells me that not all coax connectors are equally susceptible to the problem.

I eventually ended up installing a new dedicated circuit for the HT gear anyway; if changing to toslink isn't an option that's probably what you'll have to do, unless you want to replace the lighting with something non-fluorescent.

 

[TonyTone]

To those of you who recommended that I use optical--great idea but unfortunately my Toshiba DVD player is a slightly older model which only has coax digital audio out.:frowning:
I will try a different surge suppressor--I must admit the one I'm using is an el-cheapo one...please, no flames! In all fairness, the HT setup in my family room isn't connected to a cheap one. As a matter of fact, I'm getting a Monster HTS5100 to replace the HTS1000 currently in use, which will then be transplanted to my bedroom HT.
Seth_L--I'll take a stab at those RatShack part numbers, although I find it hard to believe that the RatShack coax digital audio cable wasn't good enough; packaging said it was "double shielded" although I can see where even that can be taken with a grain of salt...
If after doing any and all of the above I still get dropouts...well, I'll just have to remember not to turn on the bathroom fluorescents when I'm watching a movie.

 

[Seth_L]

We had our stuff on filtered UPS's at college and still had the problems, so I'm not sure how much power filtering is going to help you. I think the actual co-ax cable and adapter ends should do the trick. Either way you can't beat 'em for price and quality. It would be cheaper to get 'em from parts express than rat shack though.

Seth