Control/Dimming House lights fades in steps

D

dhock194

New Member
All - scenario is as follows:
- Elation Show Designer 2 (SD2) controller
- Elation DP-415 dimmer packs
- SD2 is controlling DP-415s for various elements -- ellipsoidal and pars (generic 1 ch dimmer each), LED fixtures by ADJ and Blizzard
- House lighting (conventional incandescent fixtures) are wired to a DP-415, but fading up or off using a preprogrammed scene shows a noticeable step function, as though the voltage to the bulbs is changing in increments of 10volts, etc (ie non-linear fade). Fading these manually does not show the same step function.
- Fade to full and fade to black works fine (very linear) on all ellipsoidal and par elements, so would not seem to be the SD2, DP-415s or the combination of the two.

Essentially, the house lights are sets of 9ea 75watt incandescent bulbs wired in parallel back to one of the DP-415 channels. If my high school electronics is right (been a long time), this would present about 5.8A at 20ohms to the DP-415 channel consuming about 675 watts...but this is not that different (A/Ohms) from a single 750w ellipsoidal on a DP-415.... the 75w bulbs are stepping through their fade, but the ellips fade fine, very linear.

Any ideas on what is happening here? We have been living with it for now, but really want to address this.

Thanks in advance!
 
What do you mean by pre-programmed scene? Where is the scene stored, and how is it triggered? What happens if you switch the house lights and one of the 750W ellipsoidals? Does the stepping issue stay on that particular DP-415 output, or does it follow the house light bulbs around? I looked up the pack, Elation claims its only good for 5A/600W per channel here, http://www.elationlighting.com/dp-415#specifications I wonder what would happen if you tried fading with 8 bulbs on the house string instead of 9.
 
dhock194 said:
All - scenario is as follows:
- Elation Show Designer 2 (SD2) controller
- Elation DP-415 dimmer packs
- SD2 is controlling DP-415s for various elements -- ellipsoidal and pars (generic 1 ch dimmer each), LED fixtures by ADJ and Blizzard
- House lighting (conventional incandescent fixtures) are wired to a DP-415, but fading up or off using a preprogrammed scene shows a noticeable step function, as though the voltage to the bulbs is changing in increments of 10volts, etc (ie non-linear fade). Fading these manually does not show the same step function.
- Fade to full and fade to black works fine (very linear) on all ellipsoidal and par elements, so would not seem to be the SD2, DP-415s or the combination of the two.

Essentially, the house lights are sets of 9ea 75watt incandescent bulbs wired in parallel back to one of the DP-415 channels. If my high school electronics is right (been a long time), this would present about 5.8A at 20ohms to the DP-415 channel consuming about 675 watts...but this is not that different (A/Ohms) from a single 750w ellipsoidal on a DP-415.... the 75w bulbs are stepping through their fade, but the ellips fade fine, very linear.

Any ideas on what is happening here? We have been living with it for now, but really want to address this.

Thanks in advance!
Click to expand...
How slow or fast is your fade time? Is this a case of the thermal inertia of your 750 Watt lamps hiding / smoothing the steps in your fades whereas the multiple smaller filaments are able to respond faster? Not that you'd want to, but if you slowed the fades on your 750 Watt lamps down to 5 minutes, would the steps in the fades begin to show themselves?
Toodleoo!
Ron Hebbard.
 
Good points made by all -- thanks!

On Bob's points:
I will try swapping, both the dimmer and the dmx cabling. Re: 8 vs 9 bulbs, the actual wiring is 9 bulbs per channel using 2 channels of the 4 channel dimmer.

Also to Bob's question, the SD2 allows programmable scenes, setting DMX values across a setup of fixtures with a selectable fade time *to* the scene. So, for example, I have a scene for house lights all up and stage lights all down, as well as one for stage lights all up and house all down. Fade time on both is currently 2 seconds,

On Ron's points:
I did try slowing the fade, and it helps visually a bit, so faster is worse, and slower face is better.
 
dhock194 said:
Good points made by all -- thanks!

On Bob's points:
I will try swapping, both the dimmer and the dmx cabling. Re: 8 vs 9 bulbs, the actual wiring is 9 bulbs per channel using 2 channels of the 4 channel dimmer.

Also to Bob's question, the SD2 allows programmable scenes, setting DMX values across a setup of fixtures with a selectable fade time *to* the scene. So, for example, I have a scene for house lights all up and stage lights all down, as well as one for stage lights all up and house all down. Fade time on both is currently 2 seconds,

On Ron's points:
I did try slowing the fade, and it helps visually a bit, so faster is worse, and slower face is better.
Click to expand...
I, Ron, was suggesting slower fade times may look worse by revealing the steps in dimming that the larger / hotter / slower to react, filaments may not be able to keep up with / react to.
Toodleoo!
Ron Hebbard.
 
With an incandescent house light system and 8 bit resolution, you still have 256 increments. I would not think that would result in any noticeable stepping. I've run small loads on DMX and never noticed it. So, how many steps are you seeing? Here is why I ask- When you are controlling colors or gobos on a mover, the profile will only allow specific DMX values to pass, for example, if you had 8 gobos, the DMX output would have 8 distinct steps.
Is there any chance a stray "profile" got loaded into the channel(s) you are using for your house lights?
 
Another odd thing might be DMX refresh rate. If it's rea-l-l-y slow then you'd see steppy fast fades.
 
sk8rsdad said:
Another odd thing might be DMX refresh rate. If it's rea-l-l-y slow then you'd see steppy fast fades.
Click to expand...
I contacted Elation about the SD2 specs being the issue -- they indicated that the fader updates 10x per second, so 255->0 fade range over the 2 second fade might see 20 steps @ 5% of fade each. I have not counted (yet) but I think I am seeing only maybe 5 visible steps or so.
 
JD said:
With an incandescent house light system and 8 bit resolution, you still have 256 increments. I would not think that would result in any noticeable stepping. I've run small loads on DMX and never noticed it. So, how many steps are you seeing? Here is why I ask- When you are controlling colors or gobos on a mover, the profile will only allow specific DMX values to pass, for example, if you had 8 gobos, the DMX output would have 8 distinct steps.
Is there any chance a stray "profile" got loaded into the channel(s) you are using for your house lights?
Click to expand...

I will check, but the fixture profile on the board is generic dimmer (1 ch), and is the same as we use on the ellips/pars without issue.
 
100ms input delay? Yeesh... That's a long time when you're trying to have keep in time with something!

When you add in the warm-up delay of a conventional, that can be quite a large discrepancy.
 
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