PA system hum. LED vs incandescent

Well, I can't say for sure, but LED Pars would probably reduce your hum problem. Running 8 Par64s is pulling several thousand watts of power through the circuit (dependent on how many you have on at a time). 8 LED models will pull significantly less power, so you hum should go away. Obviously having not seen your specific system, I can't say 'yes, this will fix your problem', but there's a good chance it will at least help. Keep in mind, however, that LED Pars (especially the cheap ones) put out next to no light. Coming off a system of industry-standard halogen 64s, cheap LED ones will most likely disappoint you. Check out the LED shootout thread on this forum for some pictures. Not to mention that some LED units, again the cheap ones, can be glitchy and problematic. I guess I'm just making sure you know what you'd be getting in to.

Hope this helps

Well, the power draw has nothing to do with hum in the PA, otherwise we would get hum when not using the dimmer pack, but we don't. The hum is definitely caused by the electronic dimmer. And it's hotter than hell without the dimmers.
Theoretically, there should be no hum caused by the dimmers, because there wouldn't be any, just the DMX controller, a Elation DMX Operator. Thanks for the shootout info, that's nice to know!

Hmm, well in that case I wouldn't be able to say much either way as to whether or not LED Pars would fix your problem. The only times that I've encountered a hum is when I'm using several thousand watts of power that somehow interferes with the sound gear. Maybe it has something to do with the way the dimmer works? I don't know, I'm just guessing now!

Does this hum only happen when the dimmer is powering lights, or when idle too? If it doesn't seem to be a wattage problem (which come to think of it, I don't see why it would be because amps draw a ton of power too), then I don't know what your problem is, except I've had it once or twice, and I really couldn't tell you if LEDs will fix the problem!

Sorry I can't help you more!

The hum is present when we fade the pars any at all when used with a dimmer pack. Without, there is no hum. But of course they're too bright. The hum interference is an inherent property in solid state dimmers, but not so with variacs, the ss predecessor. The dimmer wiki explains it all pretty well.

So really the question should be if using a DMX controller with LED PARs could there be hum interference with the PA system caused by the controller?

Could there be a problem? Absolutely, anything is possible! As before, I can't say for sure, but I don't see why there would be a problem. I've used countless DMX boards in venues ranging from theaters to clubs to my own mobile systems, and not once have I had a problem with the board itself causing a hum. On my mobile systems, the light board is almost always on the same circuit at the sound gear and there isn't any hum. Based on that, I think you will most likely be fine.

Edit: Sorry, didn't see your edit above. I've never used a DMX operator. Like I said, I've only rarely had this problem, and my mobile system is fine with the light board on the same circuit as the sound. I guess it really depends on what you're using. My mobile sound gear consists of a Mackie mixer, QSC powered tops, and Yorkville subs driven with QSC amps, so decent gear, never had a hum problem. Spilling Coke in your mixer will cause a hum problem though! (no, I've never done it, but I've seen the aftermath!)

We've got good gear too. Mackie, Crown, JBL, Cerwin Vega, White, etc. Now the dimmer packs are probably cheapo's. I'll have to check.

Are you using LED or std pars?

I use the standard 500w Par 64s. Time after time, no hum from them, but they also go on separate circuits. The light board is usually on the same circuit as the mixer.

A:
Don't use lights and audio on the same circuits. If you can do it, different transformers if at all possible a different ground.

I suspect there is a ground potential issue that needs to be checked out.

I don't have any issue if the sound console and lighting consoles are on the same circuit(they usually are), but as far as powering the lights, they should NEVER be on the same circuit as audio.

Test outlets, test your rig. Try an EbTech Hum Eliminator somewhere in your system. Isolate and find out what is causing it.

Start with audio console out to mains only. You gotta start somewhere. Add 1 component at a time until you hear hum.

It sounds like typical dimmer hum to me if it only happens while the dimmers are dimming something. I highly doubt it is the lighting console since I think the PS for a DMX Operator has no ground on it. I have also had my Hog tied in on FoH power for large scale sound systems and its never an issue.

You are correct it is the nature of dimmers that causes the hum. LEDs will not cause this hum. They don't have the SSRs in them to cause it. Once again, I have had LEDs on the same leg/circuit as audio numerous times before with no issues.

So, find another power source or go LED. Those seem to be your options.

Dimmer hums will come if you use came circuits , different circuits , heck you can run a power line from the next town and still get that hum.. It always comes usually when you dim the light usually from the 25%-75% range the hum is the worst. If using the same ground this can be the issue. Option use a de grounder. This will also get rid of HALF the buzz on any AMP.. This way alot of thought goes into theatrical installs and in many cases you will notice that the dimmers are put in a totally other room away from the stage.. Dimmers like all electronics give off frequncies..

It can also be your bulbs believe it or not.. Occasionally, lamps may generate noise when dimmed. This noise is caused by vibration of the lamp filament as the dimmer rapidly switches the lamp on. Lamp buzz, if it occurs,, is generally noisiest at the mid-range (50%) dimming level. try changing bulb manufactures of going to a less watt lamp...

I use LED par 64's and have had not one problem with any hum. i HIGHLY suggest trying them. Plus the heat is ZERO..

Only other option is invest in alot of VERY VERY expensive shielding cables for EVERYTHING and even then it still might not help... ELECTRONICS ARE A WITCH

Lamp sing only occurs with cheaper dimmers. Cheaper dimmers means cheaper SSRs and Chokes, which mean more inference or buzz. Lamps themselves don't have much to do with it. Also, going from a higher wattage lamp to a lower wattage lamp will not make lamp sing any more or less. It has to do with the amount of filament that determines amount of sing.

As for shielded cables, power and speaker/mic line are fine side by side so long as you don't have them intertwined. The must be ran parallel to each other and only cross each other perpendicularly. Likewise, when coiling power, don't make a loop, instead make a figure 8. Loops generate a magnetic field which causes problems and interference. The figure 8 cancels this out. I could explain the physics behind it, but I don't want to bore you guys with the details .

ive had some of my lamps sing on everything from leprocon dimmers to etc to edi to elation...

Ive had it happen so bad you could hear oerfectly loud and clear in the back of a theare.

Put all new lamps in my stage lights for an STYX concert a few years ago.. I had to return all of them to the manufacture which i wont name. Over 70% of the bulbs when dimmed had this issue.. Was like a damn chorus of hums.. So i was stuck walking into a local lighting store asking for 160 1000 watt par 64 lamps hehe should have seen his face...

I had to run my 64 LED Pros off the same circuit as my mains. QUIET!!

Still, my thoughts are "lights and sound should not touch".

I've also used my ADJ dimmer packs on my mains wiht Par38's: no problem. Still, breaks my recommendation. But then again, I have to do these fun things when the promoter doesn't seem to think my tech rider is of anything important.

Ah, figure 8 for power. The opposite coils phase cancel out each other. Aways best not to become an inline eletromagnent, because then it becomes a power transformer too with the coilings. Not good!

i think everyone can agree the haardest thing about all of this is trying to explain this to club owners , bar owners , theatrical management as to WHY Lighting should have its own power source away from sound...

Well, I think we'd have to speak at a volume and frequency that can penetrate a skull as well as via gluteus maximus tissue that said skull is wedged within.

Most places, as I've found is typical, sound and lights re a distant after-thought. The only places I find that have a clue are those places that are designed to be a true entertainment venue. And that's just the way it is.

With lacking power, us small timers really should invest in LED technology to make those circuits stretch further. Each year speakers become more efficient, as well as amps, but they still draw big power. Club and restaurant owners aren't going to change.

Last night, at an event, a band was using commercial grade flood lights(hardware store/construction grade stuff) and they ended up popping the circuit. I was worried about it, and sure enough, it happened. I didn't run lights, not my issue or concern. My circuit with backline and monitors kept running strong! Mains went untouched as well. In this case, it's an internet cafe that does youth-oriented shows because in all honesty, where I live, it's practically a police state. Really sucks most of the time.