Hanging powered monitors

[Rip Van Winkle]

I’ll apologize in advance for the following mess. I’m new to CB; I’ve been letting this problem for too long, and am afraid that I’ve overcomplicated the question. Please bear with me!

I am looking to hang a couple of powered stage monitors (JBL EON612’s) on a semipermanent basis, meaning that I expect the rigging & wiring to stay put even if the speakers need to be temporarily removed for scenics or whatever. I am realizing that this project hits some critical gaps in my knowledge: most theaters I’ve worked in have had fly systems; I’ve never really requested this kind of “permanent” rigging; and, most importantly, I have a 20 year gap in experience (backstory in my profile if you’re interested), which means I missed the rise of the powered speaker.

I have been having trouble finding what feel like basic best practices for powered speakers, particularly when used as monitors in a larger system (searching mostly turns up rigging fails on reddit). I want to be very clear that I am not asking for “how to” advice on rigging or electrical. A qualified rigger & electrician are precious commodities for this (school) theater — we have none on staff or even regular crew — and I want to make sure that I’m asking for the right things when I get the opportunity.

Rigging: The speakers have 3 suspension points. Attaching a picture of the proposed location. (The battens are dead hung a few feet below the grid on the ceiling; if a line came straight down from the grid, it would not interfere with the curtain rail or the acoustic reflectors.)

— What is best as a permanent installation: bringing wire rope all the way from the grid, or just rigging it (properly) to the batten? (It seems un-neighborly to permanently clog the ends of one of a very few battens; am I missing something obvious?)


Power: This is the big mystery to me. Not sure if I’ll have access to an electrician, but if I do, I want to make sure I ask the right questions:

— I’m imagining a million variables in connecting the speakers to power. I guess the most important is, where should the extensions attach to the wall? Is it okay to swag them down to deck level along the wall (again, for a long-term installation), or should I ask for a junction box up at the level of the battens? If the former, do I have one plug for both speakers, or a separate plug for each? If the latter, do I ask for some power control (a switch) at the deck level?

— Is it advisable to leave them on always? They obviously won’t see as much use as other stage systems, and would be subjected to the regular nasty pops of connecting and disconnecting of sources if they can’t be switched off.

— I’m also confused about grounding and circuits: in my day, on a small job all your powered stuff — your amps, your processors, your mixer — tended to be in one place. It was easy to plug everything into the same leg, keep it all on the same ground, and every potential bridge to any other circuit was assumed to be a hum risk (behold, the mighty direct box — or in your sketchier situations, that little grey “grounding adapter”). Has this been magically fixed in the 21st century, and I can just connect stuff to the nearest outlet? Is sound now also responsible for distributing power (or making sure power is distributed) to this degree?

As a point of information, this building was built (brand new) in 2015, so maybe my concerns are entirely historical. (Furthermore, I plan on patching through the installed “MONITOR” lines on the stage boxes. Is it possible these are wired to isolate ground by default? There’s a maddening dearth of documentation here…)



Thanks for reading this far. I appreciate all your input and advice!

 

[Crisp image]

Hi Rip,
You could run both of the speakers off one circuit. I would think you want a way to turn them off at the end of the day to preserve their power supply and prevent the thumps when connections are made. This could be a remote switch to turn off the outlet (we have this in one venue). Remember this Amps on last and off first.
As for suspension above the manufacturer has been kind enough to include factory M10 suspension points. I have used such points to hang speakers over head (short term) and depending on where the points are I did a bridle between 2 points then used the third to angle the speaker just right.
As for positioning I will leave that to more experienced people than me.
Regards
Geoff

 

[jkowtko]

When I hung my SRM450s from the grid, I used a C-clamp on the pipe with the post pointing up, then cut a thick (2 3/4" pieces glued together) plywood "yoke", with a hole in the center to fit it on top of the clamp post, from which I could mount three eyebolts and link chain to hang the speakers. This worked pretty well and between the chain link and the eyebolts in the plywood (with long shafts for adjustment) I was able to adjust the speakers into good positions. The hole in the plywood allows you to rotate the "yoke" pretty easily too.

For speakers mounted on the side walls I used a standard upright speaker pole mount (see attached pic) with the same plywood/chain hanging system.

For power I just ran extension cords all the way back to a switched outlet box on the wall next to the breaker. This box was on the same circuit as the sound booth to avoid potential hum, and the switch provided last-on first-off capability.

Unfortunately I did not take any photos of this, but if you are interested in trying out this design I would be happy to provide more details)

Thanks. John

 

[microstar]

Hi Rip,
JBL makes a hardware kit with M10 eyebolts so you can simply use appropriate chain and shackles to attach the speakers to your batten or other suspension point.


A good way to provide switched AC power to the speakers is to use a "remote power relay" which is mounted next to the speaker, as shown below. A low-voltage cable can go from the relay to your sound booth to conveniently switch the power on or off. In many sound systems, power is supplied to the components by means of a "sequencer" which powers them up or down in proper order automatically by the push of a button or turn of a key switch.

 

[TimMc]

Hi Rip.

One of the things that has not changed in 20 years is the Universal Audio Answer: "it depends..."

Is that a tab curtain on the left of your pic? I presume the loudspeakes will go on-stage of the tabs? I'm guessing the Eons were picked because they are already in inventory? I ask/speculate because without moveable battens, using the installation points in the Eons, from a fixed suspension, will make taking them down and putting them back up more labor intensive, and I'd not want to do that work from a ladder. My choice would be that whatever I hang there, will not be taken down for pep rallies, etc.

Considerations regarding powering tend to hinge on how permanent or temporary the installation is and how you access the loudspeakers when the are at height. Power sequencing, running conduit and outlets... price out that work. It will be the most expensive part of this. If you could use suitable, Listed extension cords and run power only when the monitors are needed, the cost drops considerably.

We'll talk about signal flow and mono or 2 channel in the next installment.

 

[Rip Van Winkle]

Thanks for all your replies. One thing I think I’m hearing is is that ground loop problems have not gone away, and that it’s up to sound to take that into consideration, now that the connections to power — and ground — are now distributed widely through a facility.

Is that correct? Is there a better/easier/safer way of doing this than lots of extension cords or iso transformers?

On a related note (but really a different topic), are ground loops less of a factor in digital connections? Do I have to worry about hum when I connect, say, our digital board via dSnake? If I find productive ways to connect sound & lights, is that DMX/MIDI connection a potential sound headache?

 

[Rip Van Winkle]

Is that a tab curtain on the left of your pic? I presume the loudspeakes will go on-stage of the tabs? I'm guessing the Eons were picked because they are already in inventory? I ask/speculate because without moveable battens, using the installation points in the Eons, from a fixed suspension, will make taking them down and putting them back up more labor intensive, and I'd not want to do that work from a ladder. My choice would be that whatever I hang there, will not be taken down for pep rallies, etc.

Yes, eons are inventory. (They actually own 4, but 2 have been literally collecting dust in a corner. If I’ve ever seen more than 2 in use, it was not a good use of resources.) I have proposed this as a win-win: it’s a square one monitor position that’s off the deck, and it’s out-of-the-way “storage” for speakers which were purchased as monitors.

I don’t have the level of influence to say that they’ll never come down, so I figured that the least I could do is make sure that the rigging & wiring stays put, so that how to put them back is largely prescribed.

 

[TimMc]

Thanks for all your replies. One thing I think I’m hearing is is that ground loop problems have not gone away, and that it’s up to sound to take that into consideration, now that the connections to power — and ground — are now distributed widely through a facility.

Is that correct? Is there a better/easier/safer way of doing this than lots of extension cords or iso transformers?

On a related note (but really a different topic), are ground loops less of a factor in digital connections? Do I have to worry about hum when I connect, say, our digital board via dSnake? If I find productive ways to connect sound & lights, is that DMX/MIDI connection a potential sound headache?

Ground loops are much less of a "thing" than they were 20 or more years ago. The AES finally produced a standard for equipment chassis ground and signal grounding. Gear built to that standard is much, much less susceptible to ground loops.

"Digital" is not inherently free of grounding issues as there is still analog circuity at the front and back end of the console. See paragraph 1.

The relative cost and convenience of your proposed set up depends on what your institution's physical plant dept requires for powering. If you can just throw a couple of extension cords over the batten, it's cheap. If you need outlets on the wall or grid, those will have to be in conduit, and the bill to run 2 outlets and meet Code will exceed the price of 2 Eons. That cost may cause a reassessment of relative value of the proposal.

If you install a winch system to raise/lower the Eons, see paragraph 3, sentence 4.

I'm not saying this is a bad idea, on the face it makes sense to use the Eons currently seldom-used elsewhere. My personal take is that any value derived from using existing inventory evaporates the moment you have to take them down and put them back up again unless there is a dedicated-to-task system for lowering and raising, and working at height is not a problem to reconnect them. The first time anything is damaged or a person is injured enough to see a doctor, all potential savings vanish. In the event of an injury I can see a Principal or Head Master saying "take that stuff down and never put it back." You'd be back to Eons on stands in the wings.

So my final thoughts: doing this "right" could cost between $1000 and $4000 in most places, done by contractors to Code. The $1000 worth of used Eons are "free" but cost $1k-$4k to use the way you anticipate. If a parent walked up with a $4000 cheque and said "spend this on stage stuff" would you use that fly used speakers, or look at microphones or intercom, maybe new makeup lights for the dressing rooms, build some flats or wagons? I can think of many ways to spend that would benefit more than an occasional use model built on a false economy.

Edit PS: I'd use the above as justification to dedicate a pair of speakers to the stage, and then when they go up, they stay there.

 

[Rip Van Winkle]

This is some of the best advice on just about any subject I’ve received in years. Thank you. (Good to know about the grounding improvements: as pretty much everything in the building is less than 10 years old, so I will proceed with cautious optimism.)

As if you’ve read my mind, there is in fact a parent prepared to write a big check (mostly to remedy issues with the frustratingly failing install). As generous as I understand that donation to be, you are correct: there are a million things (including, yes, dressing room lighting) which merit that money above this.

I’m slowly realizing that the most important gap in my knowledge may not be the time that’s passed between my professional experience and today, so much as the difference between working in professional theater and volunteering in a grade-school gymnatorium…

 

[Jay Ashworth]

And as someone whose dressing room mirrors are lit by transparent tungsten... find a way to use (high-end) LED lamps for that; ours have *much* more horsepower than our (nuclear-powered) HVAC does. I know people will fight you; fight back.

(Our college theatre aircon is powered by a *5300 ton* Trane chiller plant across the street that also cools the rest of the campus, and some commercial customers. Got written up in some trade mags at the time.)

 

[Rip Van Winkle]

For what it’s worth: because I’m coming into all of this now as a parent, and there’s no TD, and I see a lot of needs, I find myself digging into a bunch of stuff that should be none of my business.

This means I recently found myself reading the ESTA standard for makeup mirror illumination (ANSI E1.55 – 2016 (R2021) is the latest revision as of this post), which has been approved by Actors’ Equity. Unfortunately for you, they still like halogen, and their maximum luminance
(30,000 cd/m2) seems pretty high to me. I’m guessing this document would give you (Jay) no leverage in a negotiation, but if somebody stumbles upon this tangent in the future, I hope this helps!

(For what it’s worth, LED’s will be a pretty easy sell for us — if we can get them makeup mirrors, they will need to be moved and stored by teenagers, so the less fragile, the better.)

 

[Jay Ashworth]

For what it’s worth: because I’m coming into all of this now as a parent, and there’s no TD, and I see a lot of needs, I find myself digging into a bunch of stuff that should be none of my business.

This means I recently found myself reading the ESTA standard for makeup mirror illumination (ANSI E1.55 – 2016 (R2021) is the latest revision as of this post), which has been approved by Actors’ Equity. Unfortunately for you, they still like halogen, and their maximum luminance
(30,000 cd/m2) seems pretty high to me. I’m guessing this document would give you (Jay) no leverage in a negotiation, but if somebody stumbles upon this tangent in the future, I hope this helps!

(For what it’s worth, LED’s will be a pretty easy sell for us — if we can get them makeup mirrors, they will need to be moved and stored by teenagers, so the less fragile, the better.)

Luckily, none of my houses are Equity.

 

[MNicolai]

(Our college theatre aircon is powered by a *5300 ton* Trane chiller plant across the street that also cools the rest of the campus, and some commercial customers. Got written up in some trade mags at the time.)

That's a hefty CEP. We just finished a project for a downtown chiller plant that has about half of that capacity which feeds something like a dozen municipal buildings and the ability to sell to commercial costumers. It's a pretty big trend in Florida for campuses to use large chilled water solutions. They'll often do a lot of their generation at night time during off-peak hours to make ice and then burn through that ice during daytime/on-peak hours, generating chilled water at the times of day with the lowest electricity rates. But lo, an extremely robust chiller plant doesn't mean much if the AHU's are getting old, the HVAC loads were misunderstood during design, or the systems aren't balanced properly.

This does make for some interesting design considerations when it comes to theaters. For example, if a high school is going to shut their chillers down after-hours, we have to think about how that impacts use of the theater on a day where the rest of the building may be dark but the theater has 800 people in it. Also means certain rooms like data closets, rack rooms, etc, need to have split systems so they can be cooled 24/7 and so we can put them on a generator for standby power much easier than it is to do with an entire 300 ton chiller.

This is the blessing and the curse of working for a large MEP engineering firm. I have projects where I'm the theater consultant and often spend more time talking about chillers and air handlers. One current project -- we're doing an air handler, chiller replacement, and seating system replacement with possibility of a larger scale interior gut-and-redo. The ability to do one AHU at a time and bring in a temporary chiller to keep the building cool is actually quite important in being able to do an intense overhaul in 6 weeks and otherwise keep the building operating and generating revenue while the contractors leapfrog around the building to replace a system at a time without interruption of the venue's ability to sustain itself financially.

For what it’s worth: because I’m coming into all of this now as a parent, and there’s no TD, and I see a lot of needs, I find myself digging into a bunch of stuff that should be none of my business.

This means I recently found myself reading the ESTA standard for makeup mirror illumination (ANSI E1.55 – 2016 (R2021) is the latest revision as of this post), which has been approved by Actors’ Equity. Unfortunately for you, they still like halogen, and their maximum luminance
(30,000 cd/m2) seems pretty high to me. I’m guessing this document would give you (Jay) no leverage in a negotiation, but if somebody stumbles upon this tangent in the future, I hope this helps!

(For what it’s worth, LED’s will be a pretty easy sell for us — if we can get them makeup mirrors, they will need to be moved and stored by teenagers, so the less fragile, the better.)

That's pretty silly given that performers will ultimately be illuminated by LED's.

Though I will say that I went down this rabbit hole recently and it wasn't remotely worth the amount of time a dozen different people ended up investing in it. The simple task was getting TM-30 data for proposed dressing room lighting. I gave the criteria, and in the period of 2 weeks, received about 2-dozen inaccurate sets of SPD's to calculate the TM-30 results from. Architectural lighting fixtures will have several configurations each -- different luminosities, CRI's, color temperatures. The lighting rep, time and time again, gave the wrong info. Wrong color temperatures and often the CRI 80 version of a fixture instead of the CRI 90+. If manufacturers simply posted all the SPD's, this would've still been an arduous task but at least I could've largely done it on my own. After two weeks of RFI's, email chains between 6-7 people (myself, architect, electrical engineers, lighting rep, etc.), I quite simply had to tap out and give up. Told them 3200K and CRI 90+. At which point the EE (who works for a competitor of ours) was still determined to meet my criteria but I had to repeatedly tell them to stand down and stop wasting their time because in another two weeks, we still wouldn't have valid data and would still be struggling to close this RFI. After that ordeal, I have no exception to someone like ETC getting into the makeup mirror lighting market because it's downright exhausting to navigate the color quality gauntlet otherwise. Many projects, especially at the K12 level, don't care, but if the question gets asked, it's an Alice in Wonderland rabbit hole to close it out.

Aside from all that, along the way I had to explain TM-30 criteria 6-7 times. Even for the few who were at least vaguely aware of it, they were not aware of the nuances between TM-30-15, TM-30-18, and TM-30-20. Like many other standards in the entertainment industry, technical superiority means very little if you have to drag the rest of the industry along with you kicking and screaming. Try finding TM-30 data as-is on the average architectural fixture. 97% chance you fail. In the 3% chance you find it, odds are it's -15 or -18 and you have to manually translate to -20.

On the AV side, Dante has been disparaged compared to AVB/Milan/AES67/etc, but the simple fact is that Dante smothered every other standard because it was downright idiot proof in spite of many people's attempts to overcomplicate their implementation of it. TM-30, on the other hand, has missed the mark on being idiot-proof and has missed the target goal of gaining widespread adoption by a couple thousand miles because it overlooks how manufacturers actually post data and requires too much of people simply interested in making money on commission of fixture sales to implement. There will never be widespread adoption of TM-30 in its current implementation. So the fallback of demanding tungsten fixtures for dressing rooms will stand because it's easy. And for those who aren't familiar with how this works, typically a project bids out between 2-3 lighting reps. One lighting rep will used as the basis of design, and they will select almost every fixture in the building. Then when other lighting reps bid against it, they'll bid based on the fixtures available in their own portfolios and try to undercut the primary lighting rep -- and all of these reps work on commission so even though they are extremely helpful, they are very self-interested. When everything is said and done, color quality isn't even an asterisk because a couple dozen fixtures in a dressing room are negligible compared to the total cost of lighting a building.

/end rant

 

[Rip Van Winkle]

That's pretty silly given that performers will ultimately be illuminated by LED's.

Good point — you’d think language more like “makeup lighting will be consistent with stage lighting” would be a better baseline from the actor/designer perspective (though I imagine the facilities/bean counters pushed for a broader standard).

Thinking about matching the color and quality of light between the dressing room and stage, I can’t help but be reminded of this famous shot from 1937’s otherwise forgotten “Sh! The Octopus”, reportedly achieved by shifting a graduated red-blue (probably) filter across the lens — lighting makes all the difference!