Rhyme or reason to dimmer assignments?

TJCornish

Well-Known Member
Joined
Mar 27, 2012
Location
St. Paul, MN
My background is more R&R than theater, so maybe I'm missing something dumb here that you can fill me in on.

We joined a church a few months ago and I'm replacing an Express 250 with a Martin M-PC/M-Touch//M-Play, which will allow us to use LEDs and movers in the near future. Last night I spent some time on the new board trying to find all the dimmer channels, and the only things that are sequential are the house lights. Everything else is scattered everywhere.

The room has 2 Sensor+ racks and ~192 dimmers. There are 3 above-stage electrics, plus a square cat walk system. In all of these places, it seems like there are 2 or 3 dimmers next to each other, then it jumps an arbitrary number of channels to numbers quite far away. For example, one section is something like 21, 22, 37, 41, 130. The whole room is like this. The dimmer racks themselves are similarly random - one module says 81 82, the next is 129 130.

I understand the theory of balancing load on the electrical phases and I suppose I understand balancing load between the two dimmer racks, but this seems unnecessarily complicated to me. I forgot to take a picture of the lighting plot - I will grab that when I'm there on Sunday and post it.

This isn't going to be a particularly significant problem as we will work with groups of fixtures 99% of the time and will hardly ever have to go to the fixture patch directly, but I'm curios as to what the thought process may have been. Am I missing something here?
 

dbaxter

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Premium Member
Joined
Mar 10, 2007
Location
Rochester, NY
I wish my background was Rest & Relaxation. I suspect the original plugging was influenced by the load considerations you mention. But once you set up your soft patching of the groups, it really shouldn't matter. You can put 21, 22, 37, and 41 into channels 1-4.
 

Jacob Brooks

Member
Joined
Mar 6, 2017
Location
Texas
Normally the electrician lands things wherever he wants when the system is installed. After that it's up to the turn on tech and the end user to make it work. As for as the numerical spacing on the rack, you are correct; loads are spread between 3 phases but you can change the patch of the fixtures in your console to make more sense to you or the programer.
 

SteveB

Well-Known Member
Joined
Mar 20, 2004
Location
Brooklyn, NY
I layed out our dimming system with dimmer/address 1 being the first circuit on SL of 1 Elec. It goes sequentially thru the numbered electrics and all on-stage, then goes to FOH. My "theory" was if we found ourselves re-hanging, most likely it would be the overheads, thus I started with low numbers and stayed with a scheme that's easy to remember. In practice we only re-hang a rep. plot twice per year.

Most consultants seem to start with 1 out in an FOH catwalk and in truth that's OK as well.

In practice it matters not and could be completely random in our house as I typically just assign Channel, Color, Purpose to stuff in Lightwright, that puts it into Vectorworks and it also goes as a patch file to Nomad and into the console, so I really never pay much attention to dimmer numbers.
 

icewolf08

CBMod
CB Mods
Joined
Jan 11, 2007
Location
Lititz, PA
My background is more R&R than theater, so maybe I'm missing something dumb here that you can fill me in on.

We joined a church a few months ago and I'm replacing an Express 250 with a Martin M-PC/M-Touch//M-Play, which will allow us to use LEDs and movers in the near future. Last night I spent some time on the new board trying to find all the dimmer channels, and the only things that are sequential are the house lights. Everything else is scattered everywhere.

The room has 2 Sensor+ racks and ~192 dimmers. There are 3 above-stage electrics, plus a square cat walk system. In all of these places, it seems like there are 2 or 3 dimmers next to each other, then it jumps an arbitrary number of channels to numbers quite far away. For example, one section is something like 21, 22, 37, 41, 130. The whole room is like this. The dimmer racks themselves are similarly random - one module says 81 82, the next is 129 130.

I understand the theory of balancing load on the electrical phases and I suppose I understand balancing load between the two dimmer racks, but this seems unnecessarily complicated to me. I forgot to take a picture of the lighting plot - I will grab that when I'm there on Sunday and post it.

This isn't going to be a particularly significant problem as we will work with groups of fixtures 99% of the time and will hardly ever have to go to the fixture patch directly, but I'm curios as to what the thought process may have been. Am I missing something here?
For installed dimmer racks, the racks are divided by phase such that the top 1/3 of the rack is phase A, the middle is B, and the bottom is C. The dimmers are assigned alternating phases for each pair (single module). As such, module 1 would be dimmers 1 & 2, Module 2 would be dimmer 7&8, etc. Module 32 would be dimmers 3&4, and module 64 would be dimmers 5&6. This "arbitrary" numbering helps to balance loads on installed systems. This is typically different than touring racks which are usually laid out linearly with the phases. This is because the load on a touring rack is usually planned out and doesn't change over the course of a tour. Whereas in a PI (permanent install) the loads are not planned and always change.

As to physical location of dimmed circuits in the room, if the raceways are not laid out in order, that is either poor design, or it was designed with a specific system in mind that has since been altered. There are some venues where raceways were laid out in a McCandless style, where the raceway would have circuits that are ganged together across the center line. So it may go something like this: 1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6. The idea being that you wouldn't have to run jumpers and 2-fers to achieve your 45 degree lighting pairs. This doesn't quite sound like how your venue is laid out.

Since you have sensor racks, you could re-assign the DMX addresses to the physical dimmers and thus make the outputs make sense. You would just need to label the crap out of everything so that you know what you are actually connecting fixtures to.

Of course the reality is, this is why we have the ability to soft-patch in every modern lighting desk. You can just assign the dimmers to the channels you want them to be and lay everything out logically.
 

TJCornish

Well-Known Member
Joined
Mar 27, 2012
Location
St. Paul, MN
For installed dimmer racks, the racks are divided by phase such that the top 1/3 of the rack is phase A, the middle is B, and the bottom is C. The dimmers are assigned alternating phases for each pair (single module). As such, module 1 would be dimmers 1 & 2, Module 2 would be dimmer 7&8, etc. Module 32 would be dimmers 3&4, and module 64 would be dimmers 5&6. This "arbitrary" numbering helps to balance loads on installed systems.
- Thanks - other than owning a SmartPack about 15 years ago I don't know much about ETC's dimming equipment. I assumed the racks would be like a circuit breaker panel with the modules alternating A, B, C, A, B, C, etc. This is probably part of the mystery, but it's not the whole story as the dimmer racks aren't as simple as your layout above, and the circuit labeling in the air doesn't follow the same spacing either. At least the electric labeling matches the dimmer number, so I'm grateful for that.

The person who designed this system (no longer with the organization and gone before my time) has an interesting reputation. It would not surprise me if ETC suggested something more intuitive, only to be overruled for esoteric reasons.
 

BillConnerFASTC

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Joined
Jan 30, 2010
Location
Clayton NY 13624
I spend a great deal of time on circuit layout and numbering, trying to come up with a system whose logic will be understood if not appreciated. For stage circuits, I rarely worry about balancing phases because there is no predicting what portable unit will be plugged into what and what will be on at any given moment. Having metered rack feeds, its almost astounding how little out of balance they are during a typical show.

This sounds like a budget electrical contractor with no good direction from the system designer who did not understand that unlike an ordinary circuit breaker panel and circuits with receptacles, it matters with individually dimmed circuits.
 

Mac Hosehead

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Joined
Sep 10, 2014
Location
Shark Tank
I spend a great deal of time on circuit layout and numbering, trying to come up with a system whose logic will be understood if not appreciated. For stage circuits, I rarely worry about balancing phases because there is no predicting what portable unit will be plugged into what and what will be on at any given moment. Having metered rack feeds, its almost astounding how little out of balance they are during a typical show.

This sounds like a budget electrical contractor with no good direction from the system designer who did not understand that unlike an ordinary circuit breaker panel and circuits with receptacles, it matters with individually dimmed circuits.
To that end, I usually see creative circuit numbering in buildings that have retrofitted their original lighting system. New buildings with new lighting systems will normally have a hookup chart for the electrician to follow. Retrofitted systems won't always have detailed hookups. I did run across a new system where the contractor made some wiring errors and then never showed up to fix them. The easiest solution was to reprogram the rack to fix the numbering.
 

JD

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Joined
Jan 1, 2005
Location
North Wales PA
In a properly designed system, there is no real need to balance phases. However, are you sure all the equipment was installed at the same time, or somebody didn't change things around after the install?
None-the-less, the actual lay of the circuits is not really relevant on a modern system as you can change the patch to end up with the board channels in whatever logical arrangement makes you happy.
Since movers and LEDs like numerical blocks of channels, I would put all of those on a separate universe on the board, even if it requires running some new DMX. At that point, you could patch all the dimmers on U1 and if you wanted, patch them so that the entire rig runs House Left to House Right chn's 1 to 192. (or whatever arrangement you like.) With the help of a brother P-touch, you could then label your connectors B1 to B192 (board.) No need to get into rewiring anything.
 
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BillConnerFASTC

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Joined
Jan 30, 2010
Location
Clayton NY 13624
To that end, I usually see creative circuit numbering in buildings that have retrofitted their original lighting system. New buildings with new lighting systems will normally have a hookup chart for the electrician to follow. Retrofitted systems won't always have detailed hookups. I did run across a new system where the contractor made some wiring errors and then never showed up to fix them. The easiest solution was to reprogram the rack to fix the numbering.
Easiest up front but a royal pita for future folk if the cem ever crashes. I would never leave that to the building.
 

BobHealey

Active Member
Joined
Aug 6, 2011
Location
Troy, NY
A venue started life with a rather "creative" system, but has since re-wired to something saner. It opened with 192 circuits of K96 dimming with the intent of using 1.2KW quad modules. As they didn't have enough money to fully populate the rack in 1982, they laid out the circuits in the rack so that if a module was in a given slot, odds are good all for circuits would be used, to maximize usable dimmers and minimize module moves until they could come up with enough funds to fully populate the rack. When they swapped it out for a Sensor+ system, the wiring was corrected so each pipe was linear. There are 1-2 places where the legacy numbering persisted, but they were odd 1-2 circuit drops anyways.
 

John Palmer

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Apr 28, 2014
Location
Cerritos, CA
ETC SR48 racks come in two main flavors; straight 1-96 or phase balanced 1-2,7-8,13-14,3-4,9-10,15-16...
I prefer the straight racks.
It is possible that if it was an installation replacing other dimmers, that the EC landed the wires where they reached.
For the most part, we soft patch around conventionals anyway, so its not to big a deal. But, I do feel your pain of not having the dimmers laid out logically. I can work out which dimmer something is plugged into FOH at my theatre based on where it is.
Take care,
John
 

RonHebbard

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Premium Member
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Jun 12, 2004
Location
Waterdown, ON, CA
A venue started life with a rather "creative" system, but has since re-wired to something saner. It opened with 192 circuits of K96 dimming with the intent of using 1.2KW quad modules. As they didn't have enough money to fully populate the rack in 1982, they laid out the circuits in the rack so that if a module was in a given slot, odds are good all for circuits would be used, to maximize usable dimmers and minimize module moves until they could come up with enough funds to fully populate the rack. When they swapped it out for a Sensor+ system, the wiring was corrected so each pipe was linear. There are 1-2 places where the legacy numbering persisted, but they were odd 1-2 circuit drops anyways.
If "they" didn't fully populate the rack initially, I hope "they" at least dealt with closing openings and facilitating proper ventilation.
Toodleoo!
Ron Hebbard
 

BobHealey

Active Member
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Aug 6, 2011
Location
Troy, NY
If "they" didn't fully populate the rack initially, I hope "they" at least dealt with closing openings and facilitating proper ventilation.
Toodleoo!
Ron Hebbard
I don't know. When I got there in 2000, the K96 was fully populated. I'm just going from the historical information about why the numbers were so weird. And it had to have been fully populated by the time Kliegl closed up shop.
 

TJCornish

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Joined
Mar 27, 2012
Location
St. Paul, MN
In a properly designed system, there is no real need to balance phases. However, are you sure all the equipment was installed at the same time, or somebody didn't change things around after the install?
None-the-less, the actual lay of the circuits is not really relevant on a modern system as you can change the patch to end up with the board channels in whatever logical arrangement makes you happy.
Since movers and LEDs like numerical blocks of channels, I would put all of those on a separate universe on the board, even if it requires running some new DMX. At that point, you could patch all the dimmers on U1 and if you wanted, patch them so that the entire rig runs House Left to House Right chn's 1 to 192. (or whatever arrangement you like.) With the help of a brother P-touch, you could then label your connectors B1 to B192 (board.) No need to get into rewiring anything.
The building was built in 2007 and was supervised by the person who designed the system until that person left several years ago. I'm confident there have been no changes to the system since the original designer left, but it's possible things were changed around shortly after the initial Install.

I can certainly patch around the mess and abstract it with groups so it's certainly not a terminal problem. My question was more for curiosity sake. I try to avoid presuming my predecessor was an idiot, and asking questions as to why the present situation is the way it is has enlightened me several times in my life. If I get bored enough, I may try to go a bit deeper in understanding this, but I'll probably just live with it.

Thanks for the thoughts.
 

BillConnerFASTC

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Joined
Jan 30, 2010
Location
Clayton NY 13624
Well, they could be labeled PR, PB, PG, OPR, OPB, OPG, and so on. I'm not sure how that gets patched......

And I'm reminded of a prominent new building with lots of press and I think a USITT tour when it was very new. A complicated 4 digit circuit numbering system - 1.2, 2.4. 6.0. and maybe 12.0 k dimmers and many positions - and by opening I believe every receptacle label had gaffers tape and a magic marker numeral - beginning at 1 and going to the end.
 

JD

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Joined
Jan 1, 2005
Location
North Wales PA
The building was built in 2007 and was supervised by the person who designed the system until that person left several years ago. I'm confident there have been no changes to the system since the original designer left, but it's possible things were changed around shortly after the initial Install.

I can certainly patch around the mess and abstract it with groups so it's certainly not a terminal problem. My question was more for curiosity sake. I try to avoid presuming my predecessor was an idiot, and asking questions as to why the present situation is the way it is has enlightened me several times in my life. If I get bored enough, I may try to go a bit deeper in understanding this, but I'll probably just live with it.

Thanks for the thoughts.
Oh, I am sure they had their reason! I have learned over the years that the mental pain caused by trying to figure out that reason is often not worth the effort ;) It is what it is now.
 

Ric

Active Member
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Sep 15, 2008
Location
Werribee, Victoria, Australia
It may have been whoever designed your standard lighting plot, set it that way.
Our original plot had lamps number 1-17 blues (FOH, then Overhead, then cyc), 18-35 reds (FOH, then Overhead, then cyc), 36-53 Ambers (FOH, then Overhead, then cyc).
And then FOH specials were after that, then overhead specials, then the PAR bar.... then side light was added, and a mirror ball.... and then blinders.

My point is that, someone had a system at some stage that made sense to them. It has probably evolved well past the initial design and just kept getting added to.

I have wanted to renumber our system for ever, but that will be my logic, and whoever comes after me will scratch their heads about it "but why is it like this?"
 

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