ETC Dimmer Doublers

[spiffit]

Hello group! I have a question, but of course there is a backstory...

Let's say that once I had set up a dozen ETC Dimmer Doublers for a specific application, which was generally intended to not change. That is, I was overcoming a hardwiring issue in my space. Everything got set up and worked. And then I went to another space...

Let's say that I came back, to find that those dimmer doublers were now being used as straight twofers. Which, apparently, they work great as.., but i digress. I want to fix the original problem, which is now a problem again, since all the doublers have been removed.

So, here is the question: are the doublers going to work properly, after being used as straight twofers, instead of the way they were intended?

Thanks!

Josh

 

[jglodeklights]

In what way are they being used as "straight two-fers"? Did someone just patch them at the console as the same channel, did they turn off doubling at the rack? Either way it is very unlikely that someone opened the doublers up to wire around the circuitry. They should be fine. Just make sure 77v lamps are installed, the dimmers are set to double and the soft patch is good to go.

 

[spiffit]

They replaced the twist-locks with stage-pins, moved the doublers to circuits controlled by dimmers not set to doubling, and they also used 125v lamps. They were using them as a splitter, instead of to independently control two instruments.

 

[Footer]

Ya, they will work just fine. You will still have to go into the console or rack and tell it what circuits are doubled and all that fun stuff. Not the first place I have seen do this... my college's road house had twist to stagepin on all of its doublers.

 

[Floobydust]

But you will not get full brightness from them as two fers; half of the sine wave goes to one leg and the other of the sine wave goes to the other.
Filament latency will cover the 30 Hz waveform, but not completely.

Best use a real two fer unless doubling is really needed; then back to the 77v lamps.

 

[JD]

Are you sure they changed the lamps? If you take two fixtures with 77 volt lamps, plug them into a dimmer doubler adapter, and plug them into a 120 volt wall socket (or a standard dimmer) they will work fine and come up to full brightness. If you put 125 volt lamps in those fixtures, they would only come on at a pretty dim level. Here's a quick review of how the doubling system works:
Regular dimmers "dim" (or chop) the whole waveform and feed it to the light. When a channel is set to double, the top half and bottom half of the waveform are controlled separately on two channels. The "doubler" adapter contains two diodes. One passes the top of the waveform to one fixture, the other feeds the bottom half of the waveform to the other fixture. So, lets say channels 1 and 2 go to a dimmer, then a cable goes to the adapter and the adapter feeds fixtures A and B. What happens if you just plug a conventional fixture (120 volt) into that dimmer without the adapter? Channel 1 or 2 will bring the fixture to about half intensity, but bringing 1 and 2 up together will bring the fixture to full intensity. Likewise, plugging the adapter into a non-dimmed outlet will cause the diodes to rout half the power into one fixture and the other half into the other. The great part is, neither of these goofs will do any damage! The only time things start getting destroyed is if the connector on the fixture is changed and someone plugs a fixture with a 77 volt lamp into a 120 volt outlet.

 

[rochem]

Hi all,

I'm finishing up a shop order and I have a quick question for anyone who might know. I know I can twofer off of the end of a dimmer doubler (L5 connectors), but I have a few booms in my show where it would be way simpler to twofer out of the circuit (Stage Pin), then put a dimmer doubler on each leg. If I did this, would both units I plug into each side still be twofered properly? I'm like 99% sure it will be fine, but I can't recall ever doing this before, and I'm not sure if there's any weird multiplexer voodoo magic that would cause problems here.

Thanks!

 

[JD]

Quick answer: Yes. (Would work fine)

 

[danTt]

I've put a dimmer doubler on ends of a stagepin twofer and used the a side from one and the b side from the other without issues, which is similar... can't remember an occasion where I've used the a side on both, but like you, I can't think of a reason why it wouldn't work.

 

[rochem]

Thanks!

 

[xander]

Theoretically it'll work. ETC's literature on the matter conflicts itself. In one piece it says you can have up to four lamps on a single dimmer, in another it says only two (one per side). In reality we avoid putting four units on a circuit. Our general practice is you can dumb two-fer one half but don't do it to both halves of a dimmer doubler. There have been issues. Four 77v/550w lamps draw 20.2A, which is fine in theory, but may not be in reality.

You might ask Doug. He's the one that taught me.

-Tim

 

[Malabaristo]

Four 77v/550w lamps draw 20.2A, which is fine in theory, but may not be in reality.

This is it exactly. With four fixtures you're operating in the range where the breaker could trip depending on tolerances of the breaker and how far off the lamps are from their nominal power draw. Some of the documentation on the ETC website related to dimmer doubling is ridiculously old, and it's mostly the old stuff that suggests four fixtures might be okay.

It doesn't really matter how the two-fers and dimmer doublers are arranged--just the total number of fixtures per circuit. A total of 2-3 should work under any circumstances, while 4 would be a gamble.

 

[zparadox]

Ok, I am not one to post in forums but here it goes.

I am interested in using ETC dimmer doubles on my Sensor racks. My question is around the futures. Can I just change the plugs on my existing source fours, put in a 77 volt bulb and attach to the doubler or is there some special fixture that I have to use?

Thanks,
Jeff

 

[rsmentele]

It is about that simple. You do have to go into your sensor rack and change some settings as well, but the manual walks you through it. Here are two useful .pdf's from ETC, the data sheet and the manual.

 

[zparadox]

It is about that simple. You do have to go into your sensor rack and change some settings as well, but the manual walks you through it. Here are two useful .pdf's from ETC, the data sheet and the manual.

Thank you. Got the whole idea of changing the setting on the dimmer, I just wondered if I had to have some special fixture for the 77V bulb or could I just change the plug. Thanks again!

 

[hobbsies]

I've seen some caps here that doesn't have the 3rd pin available for dimmer doublers. Similar to 750 lamps, the 77v lamps have a pin on the left side if you're looking at the cap with the tail facing you. 750 lamps have the pin on the right. Most new caps should have the 3rd pin available or at least a screw you can remove to use it.