[QLab] Help With Lighting?

[Christopher Ashworth]

On Apr 24, 2007, at 7:30 AM, BareStage Theatre wrote:

> Hi Chris--
> Yes, sorry, Control Change -- long, weary day.
> I know, the Behringer manual is crap and very cryptic. That has  
> been part of
> the problem. It finally took a call to their support dept. to find  
> out that
> it does work to use Control Change. The darned chart would indeed  
> seem to
> indicate it is impossible.
> We are attempting to get Qlab to send commands to fade over a range of
> values (checking the "Fade to Control Value" box and entering a  
> value).
> Basically up from 0 to 127, and down from 127 to 0, in two  
> different cues.
> We've also tried 0 to lower values like 50 and 100 -- of course the  
> flickers
> seem a little less pronounced there, but still there.
> The flicker seems very random and is not based on how long the fade  
> cue is,
> that I can tell. There seems to be 3-8 flickers whether it's a five  
> second
> or 20 second fade. They also seem to be of different random  
> brightnesses.
> And they flicker whether the lights are rising or fading.
> The activity lights on our dimmer packs flash in sync with the  
> flickering
> lights. Again, though, they work fine with just the board alone.  
> Very odd.
> Even though our DMX cables are on 5 feet or less, would lack of signal
> termination cause all this?
> Should I uninstall the M-Audio MidiSport 2x2 Midi Support software  
> and try
> it without? I think it's just some kind of plugin.
> We are running all this on one of the old iMac gumdrop machines,  
> but it runs
> OSX 10.4.9 just fine. It is USB 1 not 2. Is any of this possibly
> problematic?
> Trying to give you everything I can think of... Hope you can help.  
> Thank for
> trying.
> --Bryon

Thanks Bryon,

This is all quite helpful information, at least from the QLab side of  
things.

The fact that the flickers are random indicates to me that it is not  
directly related to the way QLab is sending the messages.  When QLab  
fades a MIDI value, it sends the messages in a regular and repeatable  
way--you can test this by downloading MIDI Monitor and having QLab  
send your MIDI fade to MIDI Monitor:

http://www.snoize.com/MIDIMonitor/

So at the very least not all of QLab's messages are causing the  
flicker, and it may even be that the flicker is not even coinciding  
with the times that QLab sends the message.

Thus, it appears that wherever the errant signal is coming from, it's  
outside of QLab.  The bad news is that my knowledge of lighting  
hardware is slim to none, so I am unable to answer questions about  
those components.  I don't think that removing the MidiSport support  
software should affect this, and the USB type shouldn't matter,  
because MIDI messages are so small....

-C