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Electronic Theatre Controls Inc

My New Source Four LED Series 2 Fixtures Don't Exactly Match My Existing Fixtures in Direct Mode


A newly manufactured batch of Source 4 LED fixtures doesn't fully match existing fixtures

Description/Explanation of Issue

Note from Jim Uphoff, our Marketing Product Manager.

ETC has always put a priority on the quality and consistency of the light our fixtures emit.  For this reason, we include a number of methods for maintaining fixture consistency over time including tight binning of LEDs, optical fixture calibration and advanced thermal management systems.  Despite all of these steps, there are certain realities of LED technologies that will cause shifts in our products’ capabilities over time.  One change that we have seen is the continual increase in output by the LEDs themselves.  This has led to lumen gains of over 25% since the release of the Source Four LED Series 2 Lustr, for example.  Because of these gains, and because they are not consistent gains for all LED colors, this can have noticeable effects on the output in non-calibrated (Direct) mode. While these changes are beyond our control, we take the issues that this can cause very seriously.  We are continuing to work on ways to alleviate these issues, but using calibrated modes is still the best way to mitigate differences.

 It should be noted that there has only been one active change to the hardware of a Source Four LED Series 2 Lustr since its release in 2014 and that was a change of the primary optic from polycarbonate to glass.  This change also required a different layout of the LED array although the LEDs themselves did not change.  These changes had no visible effect on the output of the fixtures.  The change to a glass optic was done to avoid yellowing of the plastic over the indigo LEDs that could occur in very rare instances in which the fixture is used for prolonged periods of time.  (ie architectural installations) If a customer believes that they might have yellowing of the primary optic, they should contact technical support for a warranty repair.  Other instances of inconsistency in Direct mode are related to the issues above.  



ETC released v1.8.1 which introduced a calibrated direct mode. This will allow Source Four LED series 2 fixtures to color match each other while in direct mode. This software can be loaded onto any Source Four LED or Desire fixture, but the calibrated direct mode only applies to Source Four LED Series 2 fixtures. This only matches for color, there still may be intensity variations which will need to be adjusted manually.  


  1. Update your fixtures to v1.8.1
  2. Use your fixtures in one of the calibrated modes
  3. If using Direct in v1.8.0 or lower, set levels for each fixture individually and create color palettes 


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