Issues with Stairvill par 64’s

[Zachary O'Neill]

Hi, I’ve recently been asked to assist with a community theatre group, they have a set of 8 Stairvill Par 64 CX-3’s and are controlling them with an ETC nomad. The issue I’m having is I’m struggling to achieve a smooth fade, they always seam to stutter when fading up or down, and will often flash red before completely dimming. Is this an issue in the programming of simply an issue regarding lower quality pars, and is there anything I can do to fix this.

Thanks

[timsabre]

Do you know what control mode the lights are set to, and how are they patched on the console?

 

Those lights do have a control mode where one channel can select preset colours. It sounds like the console might be fading that channel.

[Zachary O'Neill]

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Do you know what control mode the lights are set to, and how are they patched on the console?

 

Those lights do have a control mode where one channel can select preset colours. It sounds like the console might be fading that channel.

 

They’re on 8 Channel DMX, they have a smooth fade to an extent, but whenever the dim almost complete they start to stutter

[alistermorton]

Could just be usual 8 bit fade steppiness?

 

Does it behave the same in other modes?

 

Might be a silly question but the fixtures are definitely in the patch as 8 channel? You should be able to go to into the ML controls when a fixture is selected and see if any of the other channels are in some unexpected setting.

Edited January 6, 2020 by alistermorton

[DrV]

I had a similar problem on a show using Chauvet SlimPAR Pros. They were RGBA. I had created an amberish wash with them which had a fair amount of red in it. They only have 8 bit control so the bottom end is very steppy. As they were slowly faded to black the red stayed on slightly longer than the other colours (even though they were in 5 channel mode) so there was a flash of red at the end. I ended up using just the amber on its own to get around the problem.

[timsabre]

It could well be dimming steps if you only see the problem at very low levels. However once above 10% you shouldn't see any stepping or flicker.

[richardash1981]

Other comment: try dimming very slowly. If that seems to flicker less, then you may have a refresh rate issue. 10Hz refresh looks smooth on tungsten, because the thermal inertia smooths out the control jumps. On LEDs it looks horrible because there is no inertia. Getting up to 25Hz refresh rate looks a lot less flickery because the LEDs move through more intermediate brightnesses on a normal speed fade.

[John_P]

I was about to add a pack of these - I’d only heard good things about them previously in terms of being pretty bright and reliable, given the price.

Assuming your happy with everything else are you only having an issue when fading to dark or are they a bit jumpy when moving between colours as well?

[timsabre]

I've used some of the cx4 (rgbw) versions and the only time colours are steppy is when one of the channels is right at the bottom, e.g. Fading from blue to magenta, when the red first comes in it is visibly steppy, but after the first few steps you can't see the changes.

[John_P]

I've used some of the cx4 (rgbw) versions and the only time colours are steppy is when one of the channels is right at the bottom, e.g. Fading from blue to magenta, when the red first comes in it is visibly steppy, but after the first few steps you can't see the changes.

 

Thanks Tim, I’ll give them a go.

[TomHoward]

We have loads of these but we only use them in 4-ch mode and then do all the driving from the desk. We haven’t seen a colour change during the fade, though there is a definite step between 0% and 1% but after that it’s smoother.

If you were using them on a stage without any tungsten to smooth out the bottom ends of the fades you’d probably have to program around it - we keep the tungsten on for a second longer to try cover the snap at the bottom end on long slow fades