LED Dimming problems

[dwdavedw]

I've had problems in the past with LED units not dimming out smoothly- one show with spectra cycs, another with rush pars - in two different spaces, one with an express, one with an ion. could not find a profile or dimming curve
where there wasn't a clean fade up from 0, or fade out - units would stutter at the end or beginning of curve and flash. I've used other, no-name pars that worked flawlessly in a 3rd space. Now one of my regular venues is purchasing some LED gear and I'm wondering what causes this, or how to prevent - any suggestions? Don't want to be fighting this problem for the next 10 years.

 

[Les]

Can you give us a little more info on how your fixtures are being powered, as well as the mode you're running them in (namely, the Spectra Cyc's)?

 

[danTt]

Make sure you demo whatever it is you end up purchasing, and test the curves. 16bit dimming really helps with LEDs-- I wonder if the spectra cycs you were using were set in an 8 bit mode. Most modern mid-to-high end LED fixtures can do a nice smooth fade, but it's certainly worth getting a demo and ensuring it works in your venue with your needs before committing to something.

 

[dwdavedw]

Can you give us a little more info on how your fixtures are being powered, as well as the mode you're running them in (namely, the Spectra Cyc's)?

I can't tell you, it was a year ago or so when I had the problem in that space. Didn't know if there's some kind of dirty power issue or what that could induce the problem. It was 4 units daisy chained, and
we tried every onboard setting on the units, and went thru all the dimming curves on the express. The best we could do, a bit of a flicker when it went to 0, or coming up from zero, one cue in particular we got
significant strobing as they faded out, no matter how slow I set the fade out, which was the strangest thing.

 

[dwdavedw]

Make sure you demo whatever it is you end up purchasing, and test the curves. 16bit dimming really helps with LEDs-- I wonder if the spectra cycs you were using were set in an 8 bit mode. Most modern mid-to-high end LED fixtures can do a nice smooth fade, but it's certainly worth getting a demo and ensuring it works in your venue with your needs before committing to something.

Yes - great point, will do. We did have the spectra cycle in 16 bit mode and tried every conceivable configuration and dimmer curve, could not get them completely smooth.

 

[Les]

This certainly isn't typical. I recently installed Spectra Cyc's in a space and they dim very well, as do the Elation Sixpar 200's we also installed.

Were you trying to dim these via mains?


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[dwdavedw]

This certainly isn't typical. I recently installed Spectra Cyc's in a space and they dim very well, as do the Elation Sixpar 200's we also installed.

Were you trying to dim these via mains?


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"via mains" ? not sure what you mean.

 

[SteveB]

Are you powering the LED's off dimmed circuits and/or attempting to dim them using the dimmer providing power ?.

All the above is a bad thing. The fixtures want dedicated power - Relay, Constant, wall outlet not from a dimmer, etc...

They also typically want to be controlled via DMX.

Your comment "went thru all the dimming curves on the express" lends itself to some questions as to how you are powering and controlling, thus the DMX comment.

 

[dwdavedw]

yeah, wrong choice of words - all units were run off a/c not thru dimmers of course. All running thru DMX thru the board.

 

[BillConnerFASTC]

Don't be insulted but RGBA? set for 16 bit resolution? Is "smoothing" on? I've seen good results with these with good dimming but also know we've often had some initial problems on a lot of LED fixtures based on "default" settings from the factory or by good intentions gone awry (especially Strand PL fan speeds - which can't be set by RDM). Check one and see what it's programmed for.

 

[dwdavedw]

yes, tried 16 bit, and all other options on board the units.

 

[AsherSB]

That sounds like an issue with those units, unless something's up with the console. Just to be sure I'd check all other devices in the universe with the LEDs, sometimes a loose connection or faulty cable can mess with the whole system. I've never had an issue with LEDs dimming, aside from some cheap older ones getting a bit choppy below 5%.