ETC Smart Module 2 Dimmer Buzz

[molybdenum1]

We have just installed 6 ETC Smart Module 2 dimmer packs in a small renovated theatre space. We're using the 6 circuit packs, running off of 20A 3 phase power. All of our lights are ETC - S4 Juniors and S4 Pars. We are using the extended life 575w bulbs for the lamps, I believe.

The dimmers buzz badly, especially at 50%. It does not sound like the buzzing is coming from the lights themselves, but from the dimmer packs. When we raise the level to 100% the buzz goes away. In the limited space we have, this buzzing is very distracting.

We've called ETC, who say that the problem may be with the power running to the dimmers. I have looked up threads about filament buzz, which sounds like what this might be, but haven't found anything that can fix that. Right now we're using neutral density filters and trying to run everything at full or zero, which isn't a great long-term solution. Any thoughts or suggestions for things to try? Thanks!

 

[JChenault]

We use smart modules and smart bars in our theatre. I do notice a slight buzz when moving all fixtures at once to a level of around 50%, but it quickly stops and is not loud enough to be a problem.

Shooting in the dark here, I would first try to isolate the problem. Is it every dimmer or just some of them? Is it every pack or just some of them. If it is not every pack, try moving packs around to see if the noise follows the pack or the power supply.

Is it the fixture or the dimmer ( ie plug in an extension cord to the pack, and put a fixture far away from the pack. Where is the noise coming from)

Who did you purchase these from. If a local dealer talk to them. They should be able to help.

 

[molybdenum1]

Thank you for your reply. We have noticed the buzz from every pack, so we haven't been able to isolate the problem to particular packs/power supplies. The buzz stays loud when we bring the packs up to 50%, unfortunately, and since our ceiling is fairly low (14'), it's very noticeable.

We notice the sound coming from the packs, not from the lights.

We purchased them from Norcostco in Minneapolis. That's about 5 hours from us. We will call them and see what they say, although I'm worried they'll just send us to ETC or our local electricians again.

 

[dbaxter]

It could be as simple as something being loose inside your packs. I know in older style dimmers (like the ones I have), there is a large torroidal choke used to 'clean' up the output at levels like 50%. That will vibrate and cause a buzz if loose.

 

[molybdenum1]

That's an interesting idea, and I will try and check that, although these are all completely new packs and they're all doing it.

 

[JChenault]

Did ETC explain what they meant by "the problem may be with the power"? Do they mean the voltage is low, the wave form is distorted, or what. If they are specific you could check it out. ( and let us know what power problems can cause this ).

 

[molybdenum1]

They seemed to be talking about looking at the sine wave of the power to see if something in the building was interacting with it or distorting it. We don't have the tools to do that on hand, and the local electrician hasn't been immediately helpful. I'm going to try and look into that in the future.

 

[JD]

The buzz is caused by the chokes. Basically, they produce a magnetic pattern around them in the process of filtering the output. The rougher the waveform, the louder the buzz. 30 to 60% would be the worst area. Many times, the buzz is caused loose windings on the choke. Potted chokes have fallen out of favor due to the expense, so sometimes you have to do your own potting! Since they are new, contact ETC. If this had been an older dimmer pack that was not under warranty, I would have doused them with some MFP agent. (Moisture Fungus Proof) Same stuff they dunk HMI magnetic ballasts in. GE silicon also works.

 

[RickR]

If all dimmers in multiple packs are buzzing the same it's pretty hard to blame the dimmers.

Sometimes the power company can help troubleshoot. It could be something on their side. Any other power oddities in the building??

 

[TJCornish]

Maybe I'm the outlier (which scares me a bit considering my relative inexperience), but your situation sounds normal to me. Every dimmer I've ever used buzzes to some degree in the middle range. You may be able to pot the choke, but I think you should prepare yourself for the answer "that's normal". Is there anywhere else they could go?

 

[Bubby4j]

Maybe I'm the outlier (which scares me a bit considering my relative inexperience), but your situation sounds normal to me. Every dimmer I've ever used buzzes to some degree in the middle range. You may be able to pot the choke, but I think you should prepare yourself for the answer "that's normal". Is there anywhere else they could go?

I know the NSI dimmer packs that our church has buzz some.

 

[David Ashton]

the only dimmers I ever used which were totally quiet was a ABD rack I had in the70's but it cost around 3 times the cost of the Strand, I was very confused when I fired it up in the control booth and nothing happened as I brought up the master, until I looked out the window and all the lights were on.It was around 3 times the size of the Strand too.

 

[dmc34]

Hi Moly,

Were you able to resolve this issue with your power supply? How loud/how many dBs would you say the buzz is/was? Just curious because I'm about to purchase a couple of these dimmer modules for one of our small event spaces on campus.

Thanks!

 

[molybdenum1]

We have not yet resolved the issue with the buzzing, but to be fair, we haven't done much about it in the past year. (The space is not really mine, and I have a day job. Hopefully this summer I will be able to get to it.) I don't know how many dbs it is, but it is noticeable, especially when the room is supposed to be quiet. Not enough to drown out people talking, but enough to be annoying, and possibly make it harder to understand them. Is that a good enough description?

 

[RickR]

I'd love to hear more as you troubleshoot. FYI there are free sound meter apps for smart phones. Not great tools, but the price is right.

I've been involved in various ways with several Smart-Bar/Module projects and have not noticed a big noise issue. If there is something other than hardware failure involved in your problem I want to avoid it in the future.