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Please explain to me...

Discussion in 'Lighting and Electrics' started by Techiegirly, Dec 7, 2007.

  1. Techiegirly

    Techiegirly Member

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    I feel like an idiot for even asking... I've been working in theatre for 10 years now and just recently started focusing my time on lighting. Please explain to me (and yes I've Googled it and read the Controlbooth glossary and still am left scratching my head here. Trust me the last thing I wanted to have to do is ask such a stupid question here for everyone to read) the process of choosing dimmers for circuits and channels. I know the difference between the 3 but when I plug a fixture into a circuit how do I know the dimmer number? Do I assign it? Patch it? How does the circuit get to a channel number on the board? I used to program the board sometimes in my college but it's been at least 8 years and it's one of those things I've just forgotten how to do. I'm running on a basic level here and really could use some over the top explantion.

    Thanks :oops::lol:
     
    Last edited: Dec 7, 2007
  2. icewolf08

    icewolf08 CBMod CB Mods

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    This ultimately depends on the installed system in the theatre.

    If the theatre has a "dimmer-per-circuit" (DPS) system then the number printed at the connector where you plug in your lights corresponds directly to the dimmer number.

    In a hard patch type system all the circuits throughout the theatre come back to a central patch system. This could be a slider patch or a place where you have a bunch of male ends that you can connect to receptacles that correspond to each dimmer. So you can take any circuit and connect it to the dimmer of your choice. In this type of system it is important to keep track of what circuit a light is on and what dimmer that circuit is connected to.

    Given either of the above systems once a light is connected to a dimmer you can assign the dimmer to channels in the lighting console. This is called the softpatch since it is not a physical connection. The simplest way to do this is called a "1-to-1" patch where each channel corresponds to the same numbered dimmer (i.e. Chan1=Dimmer1).

    Many people use the softpatch to group ideas together. So you might want all your front light in channels 1-15, in which case you tell the console which dimmers you want in channels 1-15. This is so that the board op and designer don't have to remember random numbers, so there can be a logical order to how to get lights on.

    So the general overview is that a fixture plugs into a circuit, the circuit gets connected to a dimmer and then the dimmer is assigned to a channel.

    Important things to remember are that you can have more than one dimmer on a channel, but not the reverse. You can have multiple lights on one circuit, but not the reverse. You can have multiple circuits in one dimmer (unless you have a DPS system) but not the reverse.

    Clear as mud? Good ;)
     
  3. JD

    JD Well-Known Member

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    Quick breakdown of the three:

    Channel:
    There are two parts to this answer. Usually the position on the board. So, you may have a 24 channel board, the first control would be called Channel 1. (In conventional dimmer systems.) Most boards and systems these days are DMX, so there is a twist: Most boards allow output soft patching, so board channel #1 could actually be patched to any DMX channel(s). Lets assume it is patched to DMX channel 1.
    Dimmer:
    The workhorse. Most DMX dimmers can also be soft patched at the stage. If you have a 12 channel dimmer pack, you set a starting address and for example if that is number 1, than dimmer #1 is running off DMX #1, which is running off board channel #1. if you soft-patched as a block, then 2 to 12 would also be DMX/board channels 2 to 12. Now, here is the beauty of DMX, if your dimmer is 2.4k per channel, and you need six 1000 watt lights on that channel, you can program multiple dimmer channels onto one board channel. In this case, three dimmers could be programmed on DMX #1 with two of the lights on each dimmer. Most packs will allow all 12 channels to be soft-patched to any DMX channel, so your 12 x 2 pack can also be a 6 x 4, or for that matter a 1 x 24k pack.
    Circuit:
    Usually refers to the limited power branch that comes off of the dimmer pack. So, we might call dimmer #1 circuit #1. In the above example where we are running 3 dimmers off of one DMX channel, the outputs of those dimmers would still be 3 circuits each with a 2.4k limit, even thought we have a total of 6k of lights running off of it.
    All of these terms are left over from the days when the dimmer system was a big cage full of autotransformer dimmers (or resistance plates if you are really really old!) and running lights required one to work out with weights first! Back then, the big handle to the top and left was dimmer #1, and the four circuit breakers that broke it down to 20 amp circuits (not always) were known as circuits 1A, 1B, 1C, & 1D. (At least until you got to the hot-patch bay, otherwise known as the death board!) The introduction of modern systems with multiple levels of soft patch have made things a little more confusing!
     
  4. Techiegirly

    Techiegirly Member

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    I think the reason I have so much trouble understanding 1-to-1 now is that the house I learned theatre in for the first 3 years of my career we had a patch bay and had to spend the time patching stuff in. It was a mess!:evil:
     
  5. Van

    Van CBMod CB Mods Premium Member

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    Ah I miss the days of the Spaghetti patch bay. Flayling around in- between scenes, or at intermission, trying to re-patch since you only had 48 6k dimmers and 196 different channels. Or the slide patch bay backstage. The one where you had to wiggle every slider to make sure it actually seated and made a connection. Or when sliding up to a channel, having sparks shoot a couple of feet out of the bay, just to keep things interesting. :rolleyes:
     
  6. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Not a dumb question at all techiegirly because the answer is so variable. This is the general approach I use to teach my beginning students.

    A circuit is series of cables that carry power to an outlet.
    A dimmer is a power supply.
    A channel is a slider on the board that tells the dimmer when to activate.

    If your theater is a dimmer per circuit system. Circuit #1 and Dimmer #1 are wired together permanently.

    If your theater is a hard patch system then any circuit can receive power from any dimmer.

    Most medium quality or better light consoles have the ability to program which dimmer is controlled by which slider on the board. This is called soft patching. If you program dimmer one to be controlled by slider 1 it is known as a 1-to-1 patch. Depending on the board however you can program channel 1 to control dimmer 87, and channel 2 to control dimmers 47 and 96... or possibly even all dimmers on one channel.

    To conclude, always keep the concepts of dimmers, circuits, and channels separate in your mind. Because while in some theaters Circuit #1 may receive power form dimmer #1 and be controlled by channel #1 on the console. In other theaters, Circuit #1 and #47 may receive power from Dimer #23 and be controlled by channel #98 on the console (which also brings up dimmer 57).

    Yeah it's a little confusing.
     
  7. Techiegirly

    Techiegirly Member

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    It's very confusing! I work in @ least 8 different houses which makes this problem a bit harder for me. :(
     
  8. Footer

    Footer Senior Team Senior Team Premium Member

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    Add on top of that importing/exporting from electrics and you can have circuits in dimmer per circ houses.
     
  9. JD

    JD Well-Known Member

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    That's where the old paper and clipboard come in handy! (in pensile !) Column 1 is your board channels,
    Column 2 is your dimmer channels,
    Column 3 is your circuits, and
    Column 4 is what lights you have on it.
    Sometimes "old tech" still works the best! ;)
     
  10. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    JD, you forgot: User Number, Rack#/Dim#, Univ#/DMX addr, Mult#/PP#... need more columns and a sharper pencil!
     
  11. Lightingguy32

    Lightingguy32 Active Member

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    ahh yes, the old Dimmer/channel/circuit cheat sheet, it works marvels when you have a great big inventory and a system that is not Dimmer per circuit. Believe me, those cheat sheets can save your life if you have to go open dimmer hunting (I have had to do that before, and believe me if you have the paper work you are at a big advantage)
     
  12. cutlunch

    cutlunch Active Member

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    Those cheat sheets are a good idea.
    A variation on them you may already be doing is having a notebok with different venue info in.
    For each venue have a model cheat sheet with just the first and last channel numbers etc.
    If it's a circuit per dimmer setup then you probably only need board channel, dimmer channel.
    A patch panel setup might have board channel, dimmer channel, circuit number etc

    You probably know you the venues so well that you won't need to make notes about other stuff. But if you work in some only once or twice a year you might jot things like load per dimmer channel down. This way if one theatre is different from the other you land up putting more lights one circuit then it can handle for this theatre. It's all little stuff but it can save time.

    Techiegirl I know you probably do this already but I thought I would mention it for our new members to give them something to think about.
     
    Last edited: Dec 9, 2007
  13. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Another thing for your "binder." Every theatre should have a chart or plan with all circuits listed. Could be an 8 1/2" x11" groundplan or a list of positions and their respective circuits. I came to a theatre seven years after it opened that had never had one. Once I drew one up and posted it several places, (Booth, dimmer room, etc.) it was used for every hang thereafter. Good to know that circuit (dimmer) #106 is on the second electric, etc. Notice the bizarre, repeating circuits on the electrics, probably for striplights, even though this theatre was designed in the 1990s and never had striplights.
    [​IMG]
     
    Last edited: Dec 9, 2007
  14. JD

    JD Well-Known Member

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    Striplights! Wow, that brings back memories! I remember every theater having striplights back in the 60's. Then, they fell out of favor as designers moved to discreet fixtures. You would go into a theater and there was always a room in the back or an area under/near the stage with a huge pile of striplights stacked up. Thanks for the quick trip down memory lane Derek!

    That's the second time in the two weeks I took that trip! George Carlin just Played the Tower Theater here last week (Phl), and someone had hung a striplight!
     
    Last edited: Dec 9, 2007
  15. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    JD, you must have missed this thread, whereby we lovingly extolled the virtues of "Xrays." After all, what is a DHA Digital Light Curtain except a fancy striplight? Gotta love 'em.
     
  16. Footer

    Footer Senior Team Senior Team Premium Member

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    Especially if you were lucky enough to be in one of those houses were the dimmers offstage had a locking handle "master" for each color so you you easily fade out entire colors....



    and for the paperwork thing.... besides having a circuit plot, which I have made a pretty good deal of for various venues,.... everyone involved in lighting a show should own a copy of lightwright.

    http://www.mckernon.com/
     
  17. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    I teach students to make a circuit chart as listed above then to take it a step further and make a channel cheat sheet. A sheet that organizes what is on every channel in logical groups. You may choose to repatch the console accordingly or not as the next step. This can be REALLY helpful to be able to find an instrument in a hurry. If you do the circuit chart in a spread sheet this is VERY easy to do... but mine usually end up on a couple sheets of paper because I'm an old fart. Basically you just want to break up what the instruments do into logical groups that make sense to YOU for the show. I suggest organizing them by gel color and what area of the stage they light. But you might also want to organize by lighting position, just areas of the stage... again whatever makes the most sense for you and the show. The goal is to have a cheat sheet to help you quickly find a channel to use an instrument.

    For example:
    R03
    Channel Area
    12 DL
    22 DC
    15 DR
    30 LC
    35 C
    39 RC
    72 UL
    75 UC
    79 UR

    Or
    Area 1
    Channel Color/purpose
    12 33 warm front
    15 51 neutral front
    17 62 cool front
    18 54 Down
    25 339 warm backlight
    37 65 cool backlight

    Again whatever works to help you quickly know a channel number... and as you can see if you set up a spreadsheet from the start that lists:
    Channel, Circuit, Dimmer, Instrument type, Gel color, Purpose, and Target Area
    It's really easy to sort them how you want.

    Not something every old pro needs, but something that will help you develop your skills. So you can focus on the design and not hunting for the right channel.
     
  18. icewolf08

    icewolf08 CBMod CB Mods

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    That seems like a start, but I tend to think of this slightly differently. Now you have to bear in mind that this only works if you are using a patchable system, whether it be hard or soft patch it doesn't matter. Think of it like this:
    The lighting designer is starting to come up with ideas for the show. He knows he needs certain systems like warm front light, cool front light, downlight template wash, warm high sides, cool high sides, etc. Then the designer looks at the groundplan and decides that he needs 15 areas to evenly cover the stage. So, his first idea, the warm front light, becomes channels 1-15 on the designers rough hookup, then the cool fronts might become 16-30 and so on.

    The designer gives all his ideas numbers and he puts those numbers on the light plot. The plot is then turned over the the theatre where the electricians start to hang it. Generally the electricians will hang the lights and then plug them into the most convenient circuit. They will then take note of the circuit number next to each channel the designer has given the lights.

    Next the electricians will patch. This ay either be a hard patch where they connect each circuit to a dimmer, or if the system is dimmer-per-circuit they will just go to the board and assign each dimmer to the channel that the LD wants. This is usually all entered into paperwork which can be as simple as an Excel spreadsheet or as complex as LightWright.

    Then, back at his office, the LD will probably create Magic sheets. Magic sheet (sometimes called cheat sheets) usually have a small copy of the groundplan for each system of lights. On the groundplan the LD places the channel numbers of each idea so that he knows where it hits on stage, and thus, the LD does not have to flip through the entire hookup and read all the descriptions to find a light.​

    After that, unless the LD is the electrician for the theatre, they are not going to care about what dimmer or circuit a light is in. All they want to know is that if they call channel 1 on, the right light should come on.
     
  19. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Definitely agree with you Alex. Like I said in that post, this organizing process may just be a step taken to decide how to repatch the console. In a high school they might not be an allowed to repatch. For a pro, organizing things like this is something they do in their sleep. With this cheat sheet, I'm trying to teach the process of how you figure out how you want to organize the information. Also with a small non-softpatchable board or on a short notice quick and dirty design, a simple cheat sheet as described can be a great solution.
     

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