More LED dimming woes

[BillConnerFASTC]

I am fortunate that I mostly work on the design of new builds. It makes it much easier to use and control LED. That is until someone insists on a decorative fixture that won't dim well and is against replacing the driver with a non-standard one. If the data say it dims to 1%, not good enough IMHO. If it says >0.1%, might not seem to pop on. They, who never go to the theatre, can't imagine that 1% looks like its popping on.

And the users - the folks running the theatre - are the ones that suffer. Just happened - architect and electrical engineer would not accept my warning, and house lights pop on to the dismay of the users.

How do I convince people that first, manufacturers' data sheets and reps lie about dimming, and good dimming to and from full off is essential. And "lets go look at it" is always greeted with "we don't have time."

 

[Amiers]

It’s like heard a pack of cats sometimes.

The EE should know that 1% is different from .01% though. I chalk that up to being lazy or just plain stubborn cause they went with the cheaper driver.

Give them recommendations on good hardware and hope for the best. Some people just don’t listen. Which sucks because that is the main reason you are there.

 

[RonHebbard]

It’s like heard a pack of cats sometimes.

The EE should know that 1% is different from .01% though. I chalk that up to being lazy or just plain stubborn cause they went with the cheaper driver.

Give them recommendations on good hardware and hope for the best. Some people just don’t listen. Which sucks because that is the main reason you are there.

@Amiers Personally, I dealt with it by no longer working for "those" people. Granted, I worked less but I was DEFINITELY happier. To me, happiness was important and still is. Sure, getting rich has its pluses but being happy's not so bad. How's your personal happiness level since you've quit lighting ponies?
Toodleoo!
Ron Hebbard.

 

[Amiers]

Less work, more money, less stress.

However I have 0 responsibilities not being in charge of the work flow anymore.

Is it bad that I miss 60ish hour weeks?

 

[JJBerman]

I would say go to the end user, and the people paying for the project.
I know that as the client paying for the new building/upgrade it will be my teams decision on what gets done or not.

Granted, in college the theatre I worked at had recently replaced some sconce lights with very dimmable compact florescent lamps.(dimming curve, pop on at 6%)
As we couldn't swap back to the incandescent lamps what we did was put the florescent lamps on a different channel and when house goes to half, that channel goes out. This worked very well as many of the audience saw the pop out as I need to quiet down for the preshow speech.

 

[microstar]

I am fortunate that I mostly work on the design of new builds. It makes it much easier to use and control LED. That is until someone insists on a decorative fixture that won't dim well and is against replacing the driver with a non-standard one. If the data say it dims to 1%, not good enough IMHO. If it says >0.1%, might not seem to pop on. They, who never go to the theatre, can't imagine that 1% looks like its popping on.

And the users - the folks running the theatre - are the ones that suffer. Just happened - architect and electrical engineer would not accept my warning, and house lights pop on to the dismay of the users.

How do I convince people that first, manufacturers' data sheets and reps lie about dimming, and good dimming to and from full off is essential. And "lets go look at it" is always greeted with "we don't have time."

I went thru this last year with a new community theatre building. Fortunately I was working for the owner and not the architect and absolutely insisted the owner's representative have a "shoot out" between the dimmable LED houselight offered up by the electrical contractor and the one I specified. The difference was immediately apparent. I won. Yes, 1% is not good enough.

 

[kicknargel]

Could you make a little one-fixture demo unit, turn off the lights in the conference room and demonstrate what 1% pop-on feels like?

 

[porkchop]

Could you make a little one-fixture demo unit, turn off the lights in the conference room and demonstrate what 1% pop-on feels like?

This. Real life examples are how I convince many customers to avoid bad ideas. At least in this case the bad units the need demoing are the cheap ones.

 

[RonHebbard]

Is it bad that I miss 60-ish hour weeks?

@Amiers No one's claiming it'll be easy but I suspect you'll rise to it with a little more effort. I have faith in you, you can do it.
Toodleoo!
Ron Hebbard.

 

[Smayniac]

I work in a couple of proudly "green" houses with LED house lighting. I have gotten around some of this by staggering the upper limit of the house light channels, one row at 100, the next at fifty, the next at 90 and so forth. It's not ideal and doesn't eliminate the pop on effect but the overall house level is not unpleasant.

 

[RickR]

Lutron used to site research that said there is a large difference between low light levels by % and the apparent brightness to the human eye. Basically 1% is like 5% and 5% is like 15% if memory serves. That at least forces them to know that numbers can mislead.

 

[Malabaristo]

Lutron used to site research that said there is a large difference between low light levels by % and the apparent brightness to the human eye. Basically 1% is like 5% and 5% is like 15% if memory serves. That at least forces them to know that numbers can mislead.

I believe this is what you're referring to: http://www.lutron.com/TechnicalDocumentLibrary/Measured_vs_Perceived.pdf

It even has a handy formula for calculating the difference between the two.

 

[BillConnerFASTC]

All supporting my original premise - dim to 1% is not very dim, and thus looks like it's popping on or off, not fading. The chat may be accurate but most manufacturer's claims of dimming are suspect. That's what I suggest looking for a claim of at least 0.1% and then testing those. Don't waste time if they say just 1%.

 

[Gobokat]

All supporting my original premise - dim to 1% is not very dim, and thus looks like it's popping on or off, not fading. The chat may be accurate but most manufacturer's claims of dimming are suspect. That's what I suggest looking for a claim of at least 0.1% and then testing those. Don't waste time if they say just 1%.

Bill,
I've also found that people still haven't wrapped their heads around the fact that LED sources aren't just fancy light bulbs, they're a whole new technology for producing light. So that "dimming to 1%" is a great spec when you're assuming that thermal inertia will keep a hot filament ghosting as it cools and completes a smooth dim out to nothing, but an LED (even with phosphor 'inertia') will drop lumen output a whole lot faster and as you have said, if the driver isn't going to maintain control to percentage of a percent then the luminaire will still pop to zero.

Side-by-sides and shootouts are something that I regularly require now that each manufacturer seems to have their own description of how great their fixtures are.

 

[PeaceTech]

There is something to be said for brightness. It looks so good and is so cool! But the real trick to showing and explaining your perspective is darkness. When an eye sits in a dark room for an hour it will understand the point you are trying to make. So, maybe a dim projector explaining this concept, and then using two fixtures (dim first) to explain this is the proper approach. This has helped me figure out the argument for the etc cyc lens....

 

[Jay Ashworth]

And remind them, explicitly, that what you're getting paid for *is to make sure that the users of the facility aren't going to have to deal with that sort of crap FOREVER*... and the people who cut the check won't be happy if you get ignored.