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One jerky fixture, not the others

Posted: Mon Jul 12, 2021 7:34 am
by ScanxTaz
'Morning all !

Hey, small question, I've a set of fixtures, and, into them, 2 scanners and 2 lyres.

When I'm using an EFX to manage position of the moving heads, the thing is going very smooth with my lyres, while with my scanners, it's very jerky and "1-FPS'ed", which gives a very bad feeling :(
Of course, I'm defining the EFS the same way, even if I use one efx for the two set (Lyres + Scans) the lyres are smooth and the scan "jerky"....


My setup :

OS : Windows 10
QLC 4.12.4
CPU : Pentium Dual Core (not charged at all)
Lyres : Miniled spot led (cheap but working well)
Scanners : JB-System DualScan (2 heads by fixture)

Thanks for your ideas.

Re: One jerky fixture, not the others

Posted: Tue Jul 13, 2021 10:01 am
by GGGss
Do you also see this 'jerkyness' in the DMX monitor?
It could be a problem with pan / tilt of your scanners being 8 bit resolution?

Re: One jerky fixture, not the others

Posted: Wed Jul 14, 2021 5:41 am
by ScanxTaz
I've the feeling that the scanners are "too quick" in going at the right position, leading to a "jerky move"...
:( and no control on speed movment

Re: One jerky fixture, not the others

Posted: Wed Jul 14, 2021 10:43 am
by GGGss
Then you have to use fade-in timing added to your positions.
But in combination with the EFX engine, this will be difficult.

Re: One jerky fixture, not the others

Posted: Wed Jul 14, 2021 11:24 am
by sandinak
So a few things here:
  • Using the same EFX on different types of heads can give different results .. that's the nature of the beast, unfortunately. Heads all handle the same config a little differently:
    • Some heads vertically depress to 110 degrees .. some go 360
    • Some heads can rotate 540 degrees .. some more or less
    • Most heads move at different speeds
    • Some heads can have a configured speed ... some can't
    • Some heads will compensate when moving fast to hit the end-setting by slowing down minutely .. some won't.
  • It's a shame you can't set the 'speed' on the scanners.. on many heads there's a speed setting for movement, and so if they're moving quickly you can slow em down a bit with a separate scene that just sets that .. and then combine the EFX and that Scene in a Collection
  • Sometimes DMX/Termination can cause jerkyness. Try moving the scanners to different positions in the chain; if you get different behavior .. start checking cables. You should also have a terminator on the end of the chain ( tho that won't help bad cables ;)
  • If you're not using true DMX cables ( 110 Ohms ) .. but (also) using XLR audio cables .. ESPECIALLY with long-length cables .. you'll get intermittent signal issues on some equipment.
  • Eliminate any empty cable on the end of the run if you can.

Re: One jerky fixture, not the others

Posted: Wed Jul 14, 2021 7:44 pm
by ScanxTaz
thanks for the advices guys :) Have a nice stage ! Euhh.. A nice day :)

Re: One jerky fixture, not the others

Posted: Wed Jul 14, 2021 7:45 pm
by ScanxTaz
btw, I'm using wireless emitter to avoid long cable and disturbance, works like a charm :)

Re: One jerky fixture, not the others

Posted: Thu Jul 15, 2021 6:47 am
by GGGss
ScanxTaz wrote: Wed Jul 14, 2021 7:45 pm btw, I'm using wireless emitter to avoid long cable and disturbance, works like a charm :)
Ow boy ... adds a new factor to the equation. You will soon know that in a controlled environment, things work perfectly. Once you get into the real world, wifi is taking all the available channels and bye-bye wireless. Jerky you said? ;)

Re: One jerky fixture, not the others

Posted: Fri Jul 16, 2021 12:10 pm
by sandinak
What @GGGs said ;) .. you might seriously grab a ladder and test with a cable ... I do quite a bit with wireless.. both the cheapy DMX dongle type and 802.11 .. learned my lessons .. and only use ArtNET+802.11 in short distances and very tightly configured. Really great write up on the dongles here. Strongly suggest reading for those considering the dongles.