Saturday, February 20, 2016

Topology and Gender

Opened a show Thursday. Started ten minutes late due to an electrical problem -- a problem I had seen coming but wasn't in a position to do more than try to correct after the fact. And that's made me think about the problem-solving toolkit. And further; it is possible this is a chicken-and-egg problem? Does the toolkit come out of domain knowledge, or can the toolkit be learned and applied by someone without that domain knowledge?

Right. Definitions first. When I have a microphone fail on stage, I have several problem-solving steps I can go through. I also have several prophylactic problem-solving steps that I try to do when setting up that microphone in the first place.

Simple example. This last show I strung cables for a house speaker and a foldback speaker across the front of the stage. Taped them down, then went to the stage snake. Potential problem here; which cable is which? They are under scenery and tape and can't be easily traced. Solution? A long time ago, I started putting ID bands on all my microphone cable. The cable to the foldback had "114" labeled on both ends. Problem solved.

A similar situation arises when I ran the cables from another speaker and a microphone (now, really, a smart tech labels all the cables with tape flags before running them, but even that is no panacea.) This was never a problem, however; the gender on each cable end is different, making it obvious which is which.

And this opens up into two of the most basic tools for keeping cabling from getting confused; gender and topology. In a sound system, particularly, most of your cabling has gender. Sound sources are male. Places where sound goes are female. With some exceptions, you can follow the arrow of male cable ends from the microphones on stage through all the snakes and mixers and processors and finally end up at a speaker.

Which means you know the purpose of any cable on the floor by the gender you see.

Topology is a similar and related problem-solving method (both prophylactic and after-the-fact.) MIDI cables, for instance, are a daisy-chain topology. You can string MIDI from one item to another, but they must go from an OUT (or THRU) to an IN. Follow the MIDI signal chain from the master (a keyboard, say), all the way out to the last slave (usually a sound module). Anything else is a mistake.

USB is a hub topology. You can never take USB out of a slave. It always starts with a host and goes to either a peripheral or a hub. And, yes; I've had musicians come up to me asking for a "USB A to USB A" cable. Nope. There can be only one (host). Everything else is in USB B, Micro, etc., etc.

Most people, I have found, run power to an orchestra pit by taking every object that needs to be plugged in and stretching it to whatever outlet is nearest. This means you have cords running every which way, and when the guitarist needs to move his amp over a foot to make room for the bass player the cord doesn't stretch and the only other outlet nearby is already filled up with music stand lights. And when someone trips on a cord in the dark things across the pit go mysteriously dead with no-one able to figure out where they need to plug in to get power back.

My method is to first determine the likely needs, then to provision outlet spaces; start from the smallest number of clearly defined sources of power, tape those cords down well, then break out in a star topology to power hubs placed in strategic parts of the pit. The thing is; you can always expand the star; plug an additional power strip into an existing power strip. And this means you always know where to look when the power fails to a trumpet player's stand light.

So what started this train of thought?

In this show, we have a blacklight effect. Several UV fluorescent strips are arrayed across the front edge of the stage. Their power cords are all gathered together into a power strip, which gets power from an extension cord which runs all the way back to the lighting table in the back of the auditorium. There, it is plugged into another power strip so that the switch on the strip can be used to toggle the effect on and off. The power for this strip comes from a nearby wall outlet.

I describe it this way because this was not in the minds of the people who were responsible for quickly loading in the show to make the morning performance. They weren't using a systemic understanding of the system, which meant they had no diagnostic toolkit to know when they were putting it together wrong -- or how to fix it with the audience already filing in and the show about to begin.

I've mentioned a previous workplace a couple of times. This was a place where magic spells were paramount. Instructions didn't just substitute for understanding; they trumped it. A case in point was when the institutional philosophy crashed into a simple light switch and was stumped by it.

There was a set of back-stage work lights, dim and blue so they didn't shine out and distract the audience during the show. One of the pre-show checks was to make sure these were turned on.

How did this institution train to achieve this goal? By substituting the goal of making sure the switch was turned on. They carefully labeled the switch (which sits, incidentally, right under one of the blue lights so that blue light clearly shines down on it when it is on), as to which direction it needed to be in.

Yes; the instruction had filtered itself to be not to turn on the lights, not even to turn on the switch, but to set the switch in the correct direction as per instruction.

And this actually worked okay (well, except for the frequent times someone read the checklist too fast and forgot to flip the switch, and the crew literally sat in the dark all show without thinking of mentioning it to anyone). But this just happened to be a two-way switch, with the other end of the switch down a rarely-used hallway.

And one day someone flipped the other switch to get the lights on.

Shock! Horror! The label is wrong now, and there is no way in heaven or hell to get the switch set to the right direction!

So they moved the label. This lasted until the (presumably) same helpful person flipped the hallway switch again.

Electricians were called about the mysterious broken switch. This was an emergency; they could not open the show without those backstage running lights, and there was no way to achieve backstage running lights if they couldn't tell which way the switch needed to be.

Eventually some kind soul explained about the two-way switch. Ah. Light dawns. Well, no. The other switch was firmly taped over with a big threatening notice to never, ever mess with it again. The label was restored on the remaining switch and it was back to business as usual. (Which is to say, forgetting to hit the switch and never, ever, ever thinking to look if the lights themselves were on.)

So my present theater company (aka the ones with the blacklight effect) haven't quite achieved this rabbit hole of mistaking the map for the territory. Their problem is more that that can't read a map and have never seen the territory.

There's this thing called theater sense. I don't know exactly how to put it, but it is a combination of knowing theater traditions, how things are usually done, and knowing exactly where you are. Theater sense tells you who to talk to when you have a costume problem. It also teaches you when to bring up a costume problem (or more importantly, when not.)

Our lighting volunteers are wonderful people but they don't have it. They aren't tuned to the flow of problem-solving going on between Director, Stage Manager, and other departments, and thus have no idea whether we are about to re-take a scene or are going on with the rehearsal. Heck; they don't seem to be able to figure out when we are actually doing a scene and when we aren't!

More apropos to this essay, however, is lack of any appropriate tool to figure out how the lights plug in. It seems to be a collection of fragments of instruction and bits of memory; the "boxes" need to have things in "1 and 3" and "the green cord" was one of the ones that comes from the lights.

Actually, I do have to give them credit. They correctly constructed the dimmer system, which requires that the Dimmer Packs get power (from a wall) and the Lighting Instruments then cascade down from the Dimmer Packs.

But the blacklight effect. When it was tested and failed, what we found was a power strip with three orange extension cords plugged into it and plugged in itself to another, all of them vanishing into a giant pile of twisted cords.

So, this is wrong at first glance; there's only one blacklight.

I took out my Chicken Stick and verified there was no power reaching the power strip itself. So, whatever it was plugged into was extraneous to the operation. I unplugged that.

Shock and horror. "That has to be plugged in; it's the cord going to the stage!"

Um, no. Not unless someone has been blatantly violating UL code on our extension cords. Remember gender? The stage is the lights. Whatever comes from stage will be male.

So I needed power to figure out which if any of the various male ends actually ran to the blacklights. Took the obviously superfluous extension cord and wriggled it out of the pile. It was far, far, under chairs, around lighting poles, back under more chairs.....until it plugged into the very same power strip it had purported to be powering.

Yeah. A perfect Ouroboros. Took that male end out of the power strip, plugged it into the wall, and the blacklights worked again. No need to figure out which was the real cord and which was another remaining error -- we needed to open the show.

But the question I started with is, how can we prevent this from happening? My method, as I showed above, is to have firmly fixed ideas of gender and topology. When I run cables, I have a sense of what each cable does and thus I am alerted immediately if something is wrong. If I'm hooking up a mic and I end up with a female XLR in my hands, I stop because I know I messed up somewhere and I need to fix it now rather than try to problem-solve it later.  (I always work backwards from stage end for exactly this reason. Also, it means I can dress the excess a the live end so if we have to move the mic, we can do so without having to pull up a bunch of tape).

But can this method -- can these kinds of methods -- be divorced from the body of domain knowledge I constructed them out of? Can you have a rule of thumb if you lack even the ability to define when it should be used -- and when it should not?

Are simplified models, arbitrary labels, "lies told to children" acceptable alternatives? Or are we going to require every volunteer we use to spend the necessary time in study to get enough grounding in the subject to where they can apply their own rules of thumb?

Myself, I can't imagine not wanting to learn. That was the biggest disconnect I had with the theater of the two-way light switch; for many of the people there, "Tell me the absolute minimum of what I need to complete this job" was their oft-stated desire. They literally rejected learning more.

In most other theaters, learning is embraced. But to people coming to the more technical end with essentially no technical background -- without even the ability to put the cords back on their home PC after dusting around it -- this appears as a monolithic, entirely daunting task. It is like someone asking if you'd like to learn to rock climb then dumping you at the foot of Half-Dome.

And I simply don't know.

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