Dimmer Doubling Control

[mstaylor]

[A spin-off of this thread: http://www.controlbooth.com/forums/lighting-electrics/26922-dimmer-doublers-mpe.html ]

I have never used dimmer doublers so I went and read about them. On the DMX side my understanding is the A side is low addresses and the B side is on the high end of 512. My question is there a limit to the number of dimmers you double, besides the obvious restriction of addresses. I also wasn't aware you couldn't use an Express to run DDs, at least not the B side.

 

[farmerjo1111]

To use dimmer doubling you need a ETC Unison or Sensor rack, dimmer double box, and a S4 fixture with a 77v lamp. You can use any DMX console with dimmer double. the B side address is the circuit number plus 256. You can use 256 circuits worth of DD. If you have an ETC console you can put it in DD mode and it will do the math for you on the B side but you don't have to. I hope this helps a little.

 

[JD]

You can use any DMX console with dimmer double.

ALMOST any DMX console. The requirement is that the console must be able to address all the way to 512 to take advantage of all 256 "second" channels.

There are some conventional consoles that will not address to 512. So, if you had a console that only addressed the first 256 channels, you would have no control over the second channel.

For example: The dimmer that was on DMX 1 is now on two channels, DMX 1 and DMX 257.

 

[rochem]

As far as I'm aware, the only limiting factor on quantity of doubled dimmers is the rating of your transformer. I've never had to use the math, but it's something to do with the KVa rating of your transformer versus the number of 77V lamps you can put on each side of each phase - I'm sure it's documented in the manual or spec sheet or something. It's important to remember that you can only fit two full racks of doubled dimmers onto a single universe, because you're essentially using 192 channels of control per rack instead of 96. Dimmer doubling also makes your circuiting more time-consuming - instead of being able to assign R1D-4 to any dimmer in the rack, you now have to remember that 1D-4 will go to the same A and B dimmer and can't be pin-patched somewhere else.. Sounds simple, but I messed it up pretty royally the first time I use DDs, and it's a different way of thinking about things.

Related question, and I hope I'm not hijacking the thread too much - could you use dimmer doubling on R20 modules? If I for some reason wanted to run two source fours as non-dims, could I drop in an R20 module and split that into an A and B as well?

 

[sk8rsdad]

Related question, and I hope I'm not hijacking the thread too much - could you use dimmer doubling on R20 modules? If I for some reason wanted to run two source fours as non-dims, could I drop in an R20 module and split that into an A and B as well?

No. R20s are mechanical relays so they do not have the necessary circuitry to allow independent control of the positive and negative half of the AC waveform. You could drop in a shoebox dimmer or other relays downstream of the R20 if you need independent control of multiple fixtures.

 

[xander]

Dimmer doubling also makes your circuiting more time-consuming - instead of being able to assign R1D-4 to any dimmer in the rack, you now have to remember that 1D-4 will go to the same A and B dimmer and can't be pin-patched somewhere else.. Sounds simple, but I messed it up pretty royally the first time I use DDs, and it's a different way of thinking about things.

What? Care to elaborate?

 

[starksk]

I also wasn't aware you couldn't use an Express to run DDs, at least not the B side.

I am not sure where you obtained that information, but it is incorrect. As of the last version of software (3.1.1), Express consoles allow you to dimmer double and patch both A and B sides referencing as A or B or as their DMX address.

 

[rochem]

What? Care to elaborate?

Sorry, I wasn't very clear. If I'm assigning non-doubled dimmers, I usually don't have dimmer 1 next to dimmer 2, and so on. I generally sort by channel within each position and assign numerically that way to start, then fudge things as needed for balancing phases and whatnot. However, the first time I did a doubled show, I did the same thing - then when it came time to put in the circuit names, I realized I couldn't have R1D-4a into dimmer 127 and R1D-4b into dimmer 166.

 

[xander]

Sorry, I wasn't very clear. If I'm assigning non-doubled dimmers, I usually don't have dimmer 1 next to dimmer 2, and so on. I generally sort by channel within each position and assign numerically that way to start, then fudge things as needed for balancing phases and whatnot. However, the first time I did a doubled show, I did the same thing - then when it came time to put in the circuit names, I realized I couldn't have R1D-4a into dimmer 127 and R1D-4b into dimmer 166.

I'm still confused. What do you mean you "don't have dimmer 1 next to dimmer 2"? I guess I just don't get your "assigning non-doubled dimmers" method and so I don't follow why you had problems with DDs...

 

[sk8rsdad]

My guess is xander typically uses a 1-to-1 patch. Setting up a custom patch would take a little longer. Not setting up a custom patch would lead to more hunting around for channels.

 

[derekleffew]

...My question is there a limit to the number of dimmers you double, besides the obvious restriction of addresses. ...

If using DMX512, one is limited to 256 dimmers doubled per universe, as the n+256 for the B side would call invalid addresses when n>256; for example, 513 thru 768.

If using a CEM+ or CEM3 or better, and DMX over Enternet protocol (Net3, Art-Net, sACN, eDMX, et al), there is no such limitation.

The A side can be referenced as:

1 (absolute address)
1A (absolute address with doubling)
1/1 (universe notation)
1/1A (universe notation with doubling)

The B side can be referenced as:

20001 (absolute address with dimmer double offset manually added)
40/33 (universe notation with dimmer double offset manually added [20,000 addresses = 39 universes and 32 addresses])
1B (absolute address with doubling)
1/1B (universe notation with doubling)

See the thread Seemingly rock solid understanding of dimmer doubling shaken by current show - Electronic Theatre Controls on the ETC forums for more.

 

[mstaylor]

I am not sure where you obtained that information, but it is incorrect. As of the last version of software (3.1.1), Express consoles allow you to dimmer double and patch both A and B sides referencing as A or B or as their DMX address.

In searching for DD info today, trying to teach myself an obvious hole in my knowledge, I thought I read that in your knowledge section somewhere that the Express wouldn't read the B side of a DD system. I will see if I can find it again. This is clearing up the hole some but not completely.

 

[starksk]

In searching for DD info today, trying to teach myself an obvious hole in my knowledge, I thought I read that in your knowledge section somewhere that the Express wouldn't read the B side of a DD system. I will see if I can find it again. This is clearing up the hole some but not completely.

If you find it again, I would love to fix it.

 

[mstaylor]

If you find it again, I would love to fix it.

It was in a comment from 2010. Here is the link:When Using Dimmer Doubling, I Can Only Control the A Dimmers, not the B Dimmers - Electronic Theatre Controls
Again I may have read something into that it said but didn't qualify.