LED HouseLights FAIL!!!

tdtastic

Active Member
Joined
Sep 16, 2014
Location
Alabama
Much to my chagrin, our school’s maintenance team has replaced all of my theatre’s incandescent house lights with LED floods as part of an energy-saving mandate. Of course, THEY DON’T DIM!!! Seeking advice from others who have found themselves trying to do this very thing.

I have 17-year-old ETC D20 dimmers, so a low-voltage module is not an option. The LED lamp that they chose is the “dimmable” Sylvania LED17 PAR38. When I contacted ETC seeking any advice on the matter I was told that, basically with my equipment, there is no great way to accomplish a fully dimmable look with nearly ANY LED lamp option.

ETC has tested and compiled a database of hundreds of LED options (by request even too) and their compatibility with the ETC product line. I was told that the LED lamp that we installed is literally on the BOTTOM of this list – the ETC rep would NOT however divulge which LED make/type had the best results when controlled with older high-voltage dimming systems. I guess I understand why they can’t legally endorse one product line over another. SOOOooo… Have YOU run into a similar problem? What LED option, if any, have you found to successfully dim in a way that is at all similar to an incandescent? Is this even possible? Any advice on the matter would be greatly appreciated!
 

KLM

Member
Joined
Apr 14, 2012
Location
Southern UT
About 5 years ago they installed LED houselights in our theatre and didn't consult anybody theatrical. It was incredibly expensive and the houselights are very difficult to get access to. At about 5-15% (The exact percent migrates) the LEDs flash back up to 100 and then finally go out. It's the worst thing ever and I hate it. No one will fix it because it was so expensive to do in the first place.

So when a show comes in and says, "At this part we want to bring the house lights up just to a glow." I have to say, "Okay, let me show you what happens when we do that..."

It's pretty embarrassing. They did another venue on our campus a couple years ago, but luckily all the fixtures dim acceptably. They're ugly as sin, but at least there's no flash...

I don't know the makes/models, so I'm not helpful... Just wanted to complain! Sorry!
 

Amiers

Renting to Corporate One Fixture at a Time.
Joined
May 28, 2009
Location
Phoenix, Az

AudJ

Well-Known Member
Joined
Jun 26, 2012
Location
Upstate NY
We installed TCP dimable led lamps last year, only in one under-balcony section, and there is a very slight "off" sudden drop when dimming, but otherwise function perfectly. I can even get them to glow as dim as the other lamps in the room. I would say I am quite impressed. They look better than the incandescent that was there. The trade-off being that little drop at the end of the dim, which I suspect might bother me more if all the lamps were led.
 

tjrobb

Well-Known Member
Joined
May 14, 2009
Location
Cedar Rapids, Iowa
We did a full Philips retrofit of our A-lines, R30's, and PAR38's. There is a certain "minimum level", but generally they work really well. In our use (community theatre) having a minimum on isn't horrible. And they are able to "glow". The only issue we've found is too - slow fades cause odd flickering (ETC Sensor rack D20's).
 

SteveB

Well-Known Member
Joined
Mar 20, 2004
Location
Brooklyn, NY
I watched some tests last year of assorted screw base LED's on both a legacy Sensor rack with D20's, as well as the same dimmers in a CEM 3 rack. The CEM3 electronics are more fine tunable and allowed a much better dim down curve as well as up from zero response.

So step one for us if/when we get the funding to upgrade our system to LED is to update the 5 CEM Plus racks to version 3.
 

MNicolai

Well-Known Member
Fight Leukemia
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Mar 30, 2008
Location
Sarasota, FL
I recommend pressing further before assuming the system is defunct. There are a few ideas of things to try that come to mind.

D20's are built for higher loads than LED's. If you put a string of Christmas lights alone on a D20 circuit, it may seem "switchy". Adding a ghost load somewhere with a few 75W light bulbs could be the difference between the dimming circuit acting like a relay or behaving like a dimmer.

My preferred option for you if not done so already would be to have your electrician add a junction box next to your dimmer rack. Buss your house light circuits together appropriately within, and then tie the grouped-together circuits into the dimming circuits you had previously used for your house lights. So if you had 30 circuits of incandescent dimming for your house lights before, you could probably consolidate those down to 5-10 circuits with the more energy efficient LED's. This consolidation of house lights on each circuit increases the loads on your dimmers, reducing your need for ghost loads. It has the added benefit of opening up more dimming circuits for production use.

Another thing to look at is the dimming curves for those circuits. Using the standard curve as configured in your Sensor CEM module looks fine on incandescent loads but look like a very sudden dimming curve on LED's. One of the other dimming curve options may have smoother fades.

Last thing that comes to mind, particularly if your LED's have been consolidated down onto one or a few circuits, I seem to recall (though I could be mistaken) that a D20 can fail in a way that makes it appear to behave like a relay. To test for this, you could power the dimmer rack down, swap a known-working D20 with a D20 feeding your LED's and see if that improves your LED dimming or not. That this is your problem is a long-shot, but not outside of the realm of possibility.
 
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JD

Well-Known Member
Joined
Jan 1, 2005
Location
North Wales PA
We installed TCP dimable led lamps last year, only in one under-balcony section, and there is a very slight "off" sudden drop when dimming, but otherwise function perfectly. I can even get them to glow as dim as the other lamps in the room. I would say I am quite impressed. They look better than the incandescent that was there. The trade-off being that little drop at the end of the dim, which I suspect might bother me more if all the lamps were led.
I have had very good results wit TCP and our houselights are on HUB dimmers from the 1980s! That being said, we have a mix of other LEDs on some of the circuits such as Philips and Sylvania. Those results are less that optimal. The good news is there are some workarounds!
As mentioned above, put at least one conventional load that is greater than 100 watts on each circuit. What happens is that some of the LED designs use a 1/2 wave rectifier (single diode) to change AC to DC inside the lamp assembly. When operated on a theater style dimmer, a DC bias develops which disturbs the trigger circuit in the dimmer resulting in misfiring the SSR. This doesn't damage anything, but produces a disastrous dimmer curve which tends to be different when you are dimming down then when you are dimming up. The ghost load brings things back to normal for the SSR and triggering circuit and cleans up it's behavior.
 

lwinters630

Well-Known Member
Joined
May 12, 2011
Location
west of Chicago
Much to my chagrin, our school’s maintenance team has replaced all of my theatre’s incandescent house lights with LED floods as part of an energy-saving mandate. Of course, THEY DON’T DIM!!! Seeking advice from others who have found themselves trying to do this very thing.

I have 17-year-old ETC D20 dimmers, so a low-voltage module is not an option. The LED lamp that they chose is the “dimmable” Sylvania LED17 PAR38. When I contacted ETC seeking any advice on the matter I was told that, basically with my equipment, there is no great way to accomplish a fully dimmable look with nearly ANY LED lamp option.

ETC has tested and compiled a database of hundreds of LED options (by request even too) and their compatibility with the ETC product line. I was told that the LED lamp that we installed is literally on the BOTTOM of this list – the ETC rep would NOT however divulge which LED make/type had the best results when controlled with older high-voltage dimming systems. I guess I understand why they can’t legally endorse one product line over another. SOOOooo… Have YOU run into a similar problem? What LED option, if any, have you found to successfully dim in a way that is at all similar to an incandescent? Is this even possible? Any advice on the matter would be greatly appreciated!
I put in 4 bulbs last year to test. They dim down to 11%. Then out. Not too bad. We are now replacing the rest. http://gc-lighting.com/wp-content/uploads/17PAR38G4DIM-PAR38-17W.pdf
 

Amiers

Renting to Corporate One Fixture at a Time.
Joined
May 28, 2009
Location
Phoenix, Az
Rant alert.

I can't find it in me to recommend house lighting that doesn't dim smoothly to full out, which leaves most LED lamp only retrofit solutions out. Bad precedent IMHO. Does the football team have to make do with such obvious imperfections in their facilities?

End of today's rant.

89% of a helmet is safe for high school, they got plenty of time to recover...
 

DavidNorth

ETC Rigging General Manager
Premium Member
Fight Leukemia
Departed Member
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Jan 21, 2009
Location
Madison, WI
It is a bit unfair to compare smooth dimming of house lights to safety equipment. House lights not dimming would be more like only chalking 89% of the lines on the field.
Agreed. Then does the football team not ever need to worry about the last yard on the first down markers. Maybe these are bad analogies, but there is value here.

If you change to LED houselights to save money, please tell me the space is in use a majority of everyday, otherwise you will not see energy savings.

If you change to LED houselights to avoid constant replacement of blown lamps and the labor caused by such, then by all means do so.

If you choose lamps that do not dim well, that is your choice, but it certainly does cheapen the feel of the space, and the art and time people put into the performance, IMHO.

Here are some things to be aware of:

- The lamps you buy today may not exist in a year. Buy spares and keep them on the shelf to deal with infant mortality. Yes, LEDs are supposed to last thousands of hours, but that doesn't mean the whole lamp will and in some cases they don't. In some cases a majority will fail in a year. Rare, but happens. Besides, you want the replacements to match in color and intensity.
- Buy a name brand. Oh, and buy a name brand - see previous point.
- Verify that the existing houselight fixture has an appropriate amount of cooling available for the LED. LEDs are different lamps and can fill the housing differently changing airflow and shortening life, especially in IC rated fixtures.
- If you test lamps in your facility, make sure all the non-LED lamps are removed from the circuit you are testing on. Incandescent and tungsten lamps can provide a great ghost load and help cancel out severe effects of current shift on capacitive lamps. Without doing this test correctly, you can end up with bottom end flicker, full range flicker or a non-dim curve once all the lamps are in the circuit. I've had people test one lamp, buy a thousand and then complain because they didn't work correctly. True story.
- Get help in testing, or buy a name brand recommended by Bill Conner. ETC tests for peak inrush, repetitive peak current, affects of multiple lamps, capacitive value and calculation of max lamps on a circuit, performance on Sensor and Unison dimmers, including older control modules, curve testing, and then provides a report. We don't publish a lot of this because we've found that lamps of certain model names made this year do not match the ones made the previous year. It's constant work and we have a full time person doing only this testing.
- Verify that your lamp is designed for forward phase dimming or reverse phase dimming [or both] and use the right dimmer.

So why would any of us want to not care about the bottom end? When fading out, this is not that big a deal, but fading up from zero, a bump to a minimum level is startling. And guess what, the audience will remember the last dramatic moment of the performance - don't let it be the houselight bump up from dark. The actor will feel cheated.

Thanks for listening, ;)

David
 

robartsd

Active Member
Joined
Apr 18, 2011
Location
Sacramento, CA
Agreed. Then does the football team not ever need to worry about the last yard on the first down markers. Maybe these are bad analogies, but there is value here.
I was thinking more along the lines of questionable calls that might be even harder to judge with the field not properly marked.
 

BillConnerFASTC

Well-Known Member
Joined
Jan 30, 2010
Location
Clayton NY 13624
And I was thinking maybe if there was a new press box that of the good-better-best choices, better might be OK. Or new blocking sled thingy - would very good be OK or must they have best? BTW, had one project where they got such a nice press box it had an elevator - probably $150,000. And you're accepting $25 LED retrofit lamps instead of a $1000 LED fixture that fims well. Save the helmet analogy for making you use a rickety A-frame instead of a genie.
 
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JD

Well-Known Member
Joined
Jan 1, 2005
Location
North Wales PA
I did an odd workaround in a room that had LED house lights to get around the smooth fade:
I set up a series of par cans aimed at the ceiling. About 5 minutes before the show, I brought the pars on and dimmed out the house lights to 0. Still a good deal of light in the room from the pars and it served as the pre-show audience cue.
Showtime- I dimmed out the pars which gave me that nice smooth low end.
 

RickR

Well-Known Member
Joined
Sep 18, 2009
Location
Spokane, WA the great "Inland Northwest"
Lots of good band-aid suggestions here. I recommend trying adding back some incandescents because it's cheap and easy. Then going to a top of the line TCP lamp. Others work well too but extensive testing is hard and often pointless. Changes in the counts per circuit can change the dimming quality. That said TCP does show up at the top of several lists for dimming quality.

One key thought is to make sure to make enough fuss to spend the money get it fixed. I would view this as a teaching moment for the school. Skipping discussing facilities issues with the primary users is just a bad idea for any administrator and you need to rub their noses in the mess. Who knows what other ideas might surface. (I have a story about clipping the tails off all the lights.)