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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Lighting Forum => Topic started by: Bob Rhead on February 09, 2021, 01:37:12 pm

Title: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 09, 2021, 01:37:12 pm
With the advances in moving lights and controls I was wondering if one could set up a small stage lighting system without employing any dimmers, just by DMX control and some fixtures.. moving or fixed (scanners?).  I understand in many new fixtures dimming is internal as part of the DMX control system.  Since the lights are full on all the time I realize that power consumption is still a major consideration.  I am just thinking about simplifying the system design.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Jeff Lelko on February 09, 2021, 02:16:48 pm
Hi Bob, yes, every modern LED light fixture (PAR, Fresnel, Ellipsoidal, etc.) is designed to run without a dimmer.  Non-LED moving lights substitute a mechanical shutter for dimming since discharge lamps can't dim 0-100%.  The only time dimmers need to be used is for conventional (incandescent) stage lights which are becoming fewer and fewer.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Paul G. OBrien on February 09, 2021, 02:32:32 pm
Short answer is YES... where have you been hiding? ;D

I mean no disrespect with that statement just trying to keep it light... too much seriousness these days. If you are new to this business or have not shopped for lighting any time recently you may not have realized that the widespread use of DMX control and LEDs have changed lighting for the better in many ways, LED sources have drastically cut electrical demands, made internal dimming and EFX easy to build-into a fixture, and reduced weight and the amount of heat generated.
Moving fixtures have long had most of this built-in. Movers with discharge lamps are still available though they are usually reserved for the larger more Pro models, but at the entry level end of the market most everything has moved to LED. LED pars have been a thing for about a decade now give or take but they are only now starting to get up to a performance level where they could replace halogen fixtures on a 1-1 basis at the large scale Professional level, there it's not just about light output color temperature also matters and being flicker free for film or TV production.
Down at the bar band or wedding DJ level there are a wealth of choices now so it is quite easy to put together an all LED package that is light, doesn't require much power and requires nothing but the fixtures and a controller although you might want to look into making at least some of the DMX link wireless to simplify setup and teardown. There are an increasing number of fixtures with built-in wireless DMX capability too.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 09, 2021, 05:49:46 pm
Yes I've been out of the lighting business for quite some time, although have tried to keep up more or less on what is out there...it just hadn't ocurred to me before that you could actually do without dimmers completely !  I confess I thought the LED fixtures still ran off dimmers so am glad to hear otherwise.  Is DMX still pretty much the control system of choice?  I thought I had heard somewhere that there was a newer IP based system that circumvents the 512 addresses / devices.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: John L Nobile on February 09, 2021, 06:04:10 pm
Yes I've been out of the lighting business for quite some time, although have tried to keep up more or less on what is out there...it just hadn't ocurred to me before that you could actually do without dimmers completely !  I confess I thought the LED fixtures still ran off dimmers so am glad to hear otherwise.  Is DMX still pretty much the control system of choice?  I thought I had heard somewhere that there was a newer IP based system that circumvents the 512 addresses / devices.

The 512 addresses is now 1 Universe and lighting is a multi-universe protocol. You should read up on it. Myself, I have a hybrid. 1 K Lekos, Pars and Fresnels and LED lights. I pretty much only use the dimmers for my front Leko lights. LED's are miles above Par cans.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Jeff Lelko on February 09, 2021, 07:10:48 pm
Is DMX still pretty much the control system of choice?  I thought I had heard somewhere that there was a newer IP based system that circumvents the 512 addresses / devices.

There are several, Art-Net and sACN being two of the most prevalent.  A DMX universe is still 512 channels, but with ethernet protocols you can send multiple universes through a single network.  This becomes handy when working with large distributed systems and/or fixtures that use large numbers of DMX channels such as pixel grids.  The benefits become fewer when working with smaller systems to the point that regular DMX outweighs any need to use networked protocols.

What kind of system are you trying to build?
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Scott Hofmann on February 09, 2021, 07:12:14 pm
About 4 years ago I spec'd the lighting for a new community theatre where everything in the auditorium was LED: ETC ellipsoidals and PARs, Altman cyc lights, RVE followspots, and Light Source house lights. Did an ETC Sensor rack with more relay modules than dimmers. They still had an inventory of conventionals from the old space.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 09, 2021, 08:49:49 pm
We have a small church here in Red Deer Alberta and looking to put in some controllable stage lighting.  I would guess we would be looking at maybe 8 or so fixtures, and a controller board.. I know I'm still thinking in 1970's mindset as that was when I worked in theatre... trying to expand my point of view!
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Dave Garoutte on February 09, 2021, 09:16:58 pm
We have a small church here in Red Deer Alberta and looking to put in some controllable stage lighting.  I would guess we would be looking at maybe 8 or so fixtures, and a controller board.. I know I'm still thinking in 1970's mindset as that was when I worked in theatre... trying to expand my point of view!
It sounds like one universe will easily do for your needs.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Brian Jojade on February 09, 2021, 11:37:21 pm
As others have said, yes, Traditional dimmers are pretty much a thing of the past.  Fixtures get sent a signal and they output what they are told.

Upside is no dimmers. Downside is you have to supply both power and a signal cable to each fixture, unless you go with a wireless system.  Wireless always has its risks though, so people still wire.  As long as you properly maintain your wires, it's not a big deal. However, an intermittent break in a cable, or a rogue fixture spitting out random DMX can become quite the nightmare if you're not ready for it!

All of my dimmers have been relegated to the annual Christmas light show.  But that too will eventually change as LEDs are becoming individually addressable at somewhat reasonable prices.  Times they keep changing.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Scott Holtzman on February 11, 2021, 01:37:47 am
As others have said, yes, Traditional dimmers are pretty much a thing of the past.  Fixtures get sent a signal and they output what they are told.

Upside is no dimmers. Downside is you have to supply both power and a signal cable to each fixture, unless you go with a wireless system.  Wireless always has its risks though, so people still wire.  As long as you properly maintain your wires, it's not a big deal. However, an intermittent break in a cable, or a rogue fixture spitting out random DMX can become quite the nightmare if you're not ready for it!

All of my dimmers have been relegated to the annual Christmas light show.  But that too will eventually change as LEDs are becoming individually addressable at somewhat reasonable prices.  Times they keep changing.


I bet some of the kids today never even seen a 100kw of dimmers. 
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Jeff Lelko on February 11, 2021, 01:33:38 pm
I bet some of the kids today never even seen a 100kw of dimmers.

Or heard 100kw of dimmers!

Bob, there's lots of great information out there on how to design a modern lighting system, but your resources might be best spent by hiring a vendor to handle your install.  Not only will they be well-versed in modern system design but can also address issues such as electrical and rigging which both need to be done by a licensed/qualified contractor.  Good luck!
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: John L Nobile on February 11, 2021, 02:02:01 pm

I bet some of the kids today never even seen a 100kw of dimmers.

Don't see them much anymore but I have no intention of retiring my CD80's. I have a 96 channel in one room and a 24 channel in another. Still haven't found an affordable LED that can replace a 1K Leko out front. But the last lights we bought were LED's and so will the next. I don't think you can give away incandescent PAR/Fresnel/Leko fixtures these days.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Brian Jojade on February 11, 2021, 06:22:15 pm

I bet some of the kids today never even seen a 100kw of dimmers.

Well, I've still got this nice dimmer rack that's filled with 7K and a few 12K dimmers. It was from at TV studio installed around 1982.

Crazy to have control of 12KW on a SINGLE dimmer.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: John L Nobile on February 12, 2021, 10:29:44 am
Well, I've still got this nice dimmer rack that's filled with 7K and a few 12K dimmers. It was from at TV studio installed around 1982.

Crazy to have control of 12KW on a SINGLE dimmer.

I didn't think it was possible but that is a gorgeous looking rack.

Dimmer Porn
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Mac Kerr on February 12, 2021, 11:23:54 am
Well, I've still got this nice dimmer rack that's filled with 7K and a few 12K dimmers. It was from at TV studio installed around 1982.

Crazy to have control of 12KW on a SINGLE dimmer.

In TV, 12k could have been a single light.

Mac
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 12, 2021, 03:32:16 pm
Thanks for all the input and suggestions.. we are all very preliminary here... !
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Brian Jojade on February 12, 2021, 07:38:46 pm
In TV, 12k could have been a single light.

Mac

Well, in this particular studio, the largest lights were 2K. However, the dimmer was attached to a patch panel where you could connect multiple lights to single dimmer channels.  You could patch up to 6 circuits to each dimmer, which would get you to that 12K level.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: John Fruits on February 13, 2021, 06:22:21 am
Well, in this particular studio, the largest lights were 2K. However, the dimmer was attached to a patch panel where you could connect multiple lights to single dimmer channels.  You could patch up to 6 circuits to each dimmer, which would get you to that 12K level.
I worked with one of those Kliegl dimmer racks for a while.  Had the 2 scene with split crossfader console.  It was a smaller 12 X 3.6KW rack with the plug patchbay.  On the smaller systems there was a countertop high flat panel with the plugs pointing up, the cable was below the counter with a weighted pully to help retract the cable.  The sockets for the dimmers were interesting since there was a circuit breaker by each socket.  When you pulled out a plug it flipped the breaker off.  When you plugged in a cable you had to flip the breaker on and the end of it covered the flange of the plug.  I have seen photos of larger systems with an angled housing over the plug bay with the cords hanging down. 
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Brian Jojade on February 13, 2021, 03:08:44 pm
I worked with one of those Kliegl dimmer racks for a while.  Had the 2 scene with split crossfader console.  It was a smaller 12 X 3.6KW rack with the plug patchbay.  On the smaller systems there was a countertop high flat panel with the plugs pointing up, the cable was below the counter with a weighted pully to help retract the cable.  The sockets for the dimmers were interesting since there was a circuit breaker by each socket.  When you pulled out a plug it flipped the breaker off.  When you plugged in a cable you had to flip the breaker on and the end of it covered the flange of the plug.  I have seen photos of larger systems with an angled housing over the plug bay with the cords hanging down.

Yup. Good description.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Mark Morley on February 15, 2021, 10:21:39 am
With the advances in moving lights and controls I was wondering if one could set up a small stage lighting system without employing any dimmers, just by DMX control and some fixtures.. moving or fixed (scanners?).  I understand in many new fixtures dimming is internal as part of the DMX control system.  Since the lights are full on all the time I realize that power consumption is still a major consideration.  I am just thinking about simplifying the system design.
Although I am commercially linked to an audio distributor, I have no commercial links to lighting manufacturers - but have spent nearly 40 years designing and installing stage lighting systems. LED lights are pretty ubiquitous now - and you can theoretically run a large number from a 13A socket. A good quality 100W LED stage light outputs approx the same amount of light (or more) as an old-fashioned 1kW incandescent (lamped) stage light. Good-quality LEDs utilise RGBA (Red/Green/Bue/Amber) LED elements, which enables the user to get any colour they like by judicious mixing of each colour's intensity. Even better are those models which include additional colours, such as Lime and additional White LEDs - these enrich the palette and enable really pleasant Whites (RGB Luminaires rarely produce a clean white light, RGBA are much better at it). Some LED lights have seven or more different coloured LED elements.
Four issues to beware of:
1): don't buy cheap! Cheap LED lights are usually unreliable and won't deliver bright enough light. They can also be VERY noisy (cheap cooling fans). You should be prepared to spend at least 500 or 600 per unit for basic wash-lights, depending upon your intended usage (basic disco lighting much cheaper). Good-quality lensed stage lights start at 800 (plus VAT) or so for Fresnels, moving up to 1,500+ for profiles. Professional-use lights cost from 1,500 upwards. LED stage lights are also available with electronic focus and, of course, moving lights offer electronically-operated pan, tilt, gobos, prisms and more.
2): Beware RCD (Residual Current Device - or Earth-Leakage Trip) issues. Each LED light bleeds power back to EARTH ("Earth-Leakage") through its electronics. Good quality manufacturers quote earth-leakage data in their literature. Any RCD protecting stage or disco lighting should be rated 30mA. According to the HSE, a 30mA electric shock is "rarely fatal" - whereas a 100mA shock is usually fatal. An old fashioned 500W stage light is rated at 2.17A (@230V) - a shock at that rating is pretty much guaranteed electrocution (ie: DEATH by electric shock)! So - if your system is protected by a 30mA RCD and you connect lots of LED lights to it - it may trip-out, if the lights' combined earth-leakage gets near to or exceeds 30mA. Make sure you spread the lights between different RCDs.
3): INRUSH. All LED lights draw INRUSH currents when they are initially switched on. This is a momentarily very high surge of power (20A-50A or so). It only occurs for milliseconds - but if the MCB (Magnetic Circuit-Breaker) or RCBO (a combination of RCD and MCB) protecting that mains circuit is the wrong type and cannot cope with such surges, it will trip-out. Good practice is to switch each LED fixture on one-at-a-time, to minimise the Inrush power-draw. Once again - don't have too many LED lights on a single power-circuit.
4): WEIGHT. LED lights are MUCH heavier than the old-fashioned lamped stage lights they replace. An LED PARcan will typically weigh 5kg or more. Be careful, therefore, if hanging your kit from lightweight lighting tripod stands, or overhead lighting bars, that were designed for use with lamped lighting. Check the SWL (Safe Working Load) that a stand or lighting bar is rated at. Simply replacing ten old lights with ten new LEDs could put your equipment under too much strain.

DIMMERS HAVE DISAPPEARED? Yes (well, they're disappearing). No manufacturer is putting any more R&D into traditional dimmer development. Many new entertainment venues are being designed without any dimmers at all. HOWEVER, in large venues, dimmers are being replaced by banks of electronically triggered relays (an electronic power switch). The system remotely switches these relays on (or off) in a cascaded manner, so that inrush problems are avoided.

ALWAYS SWITCH OFF YOUR LEDS WHEN NOT IN-USE: I have visited venues (on maintenance duties), where LED stage lights have been left on for several months non-stop. Although there is very little heat in the light beam produced by LED lights, the fixtures themselves get quite hot - and most have an integral cooling-fan or two. If left on for weeks and weeks, these cooling fans suck in dust, which settles onto the electronic cards (a dust duvet). This prevents the unit from cooling-down, leading to component failure.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 28, 2021, 10:23:34 am
Thanks Mark, great advice appreciated...I am of the same mind on quality gear and never buy based on price only. I was unaware of the RC issues... is this unique to LED fixtures.. I don't recall the term from when I worked in theatre.  Where would an RCD device go.. between the wall outlet and the fixture device chain?
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Bob Rhead on February 28, 2021, 10:38:32 am
OK I understand RCD.. just hadn't heard it referred to in those terms.. basically like Ground Fault Interupters.  I didn't know that LED fixtures bleed some voltage into the grounds.. Great to know this is an issue to consider.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Jeff Lelko on February 28, 2021, 06:38:58 pm
I didn't know that LED fixtures bleed some voltage into the grounds.. Great to know this is an issue to consider.

While I can't speak as an electrician and have never tried to measure something like this, I've never once had any sort of issue with a properly-operating fixture bleeding power into the ground.  Mark, can you provide us some literature on this to substantiate your claim?
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Scott Hofmann on March 02, 2021, 02:38:50 pm
While I can't speak as an electrician and have never tried to measure something like this, I've never once had any sort of issue with a properly-operating fixture bleeding power into the ground.  Mark, can you provide us some literature on this to substantiate your claim?
Seven or eight years ago I installed a dozen Elation IP65 fixtures outdoors at a city park; four metal poles with 3 fixtures per pole and all 12 were fed from one 20A GFCI breaker. Once we got past adding a certain number of fixtures, the GFCI would trip. The electricians removed the GFCI, installed a regular breaker, and did something to ground each metal pole as I recall, although the details are hazy. I do know they did agree that the GFCI was the problem. So I do think it had something to do with leakage current.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Paul G. OBrien on March 02, 2021, 07:30:46 pm
4): WEIGHT. LED lights are MUCH heavier than the old-fashioned lamped stage lights they replace.

This is debatable, IP65 led fixtures can be weighty but IP20 no so much, and once the weight of the power cables needed to feed a string of halogens is factored in I think the LED option comes out lighter.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Brian Jojade on March 02, 2021, 07:49:35 pm
Seven or eight years ago I installed a dozen Elation IP65 fixtures outdoors at a city park; four metal poles with 3 fixtures per pole and all 12 were fed from one 20A GFCI breaker. Once we got past adding a certain number of fixtures, the GFCI would trip. The electricians removed the GFCI, installed a regular breaker, and did something to ground each metal pole as I recall, although the details are hazy. I do know they did agree that the GFCI was the problem. So I do think it had something to do with leakage current.
Any device leaks some current, but a properly working one should not trip a breaker.  However, as you multiply devices, the amount of leakage can add up to the point that it trips the GFCI. Even things like long extension cords build up capacitance that results in current leakage.  A 200' extension cord on a GFCI circuit will often trip.

Removing GFCI breakers is not a good idea, especially in an outdoor environment.  Grounding the pole does very little to help against the type of faults that a GFCI breaker would be protecting against.  Yeah, if the chassis became completely hot, it could draw enough current to trip a breaker, but it's the partial failures that will sneak up on you.

Eg, if a fixture gets wet, current leakage can exist. If the water then finds a path to ground through someone's body, that's when bad things happen.  For example, if you go to work on that fixture and have to remove it from the pole, the leakage current now would go through you right into that wonderfully grounded pole.  Not a good situation at all!

A better solution would be to split the lights up into multiple separate circuits with a GFCI closer to where protection needs to be.  Yes, the main wire from the circuit breaker won't be on GFCI, but all of the devices downstream would be, and would then be able to provide protection.
Title: Re: Stage Lighting WITHOUT Dimmers
Post by: Jeff Lelko on March 02, 2021, 09:10:25 pm
Any device leaks some current, but a properly working one should not trip a breaker. 

I agree, and I also agree that in real world use cases there are many reasons why some current may leak out the ground (hence why it exists).  My argument is that I've never seen this spec'd as a design feature as opposed to an incidental occurrence.  Even ETC - arguably one of the most reputable manufacturers of LED stage lighting - does not include any such statement in their literature.

This is debatable, IP65 led fixtures can be weighty but IP20 no so much, and once the weight of the power cables needed to feed a string of halogens is factored in I think the LED option comes out lighter.

I agree with this too - especially if the dimmers end up in the rigging!  Mr. Morley might not yet be familiar with the ProSoundWeb trademark "it depends", along with the fact that sweeping generalizations are difficult to defend.

Good-quality LEDs utilise RGBA (Red/Green/Bue/Amber) LED elements, which enables the user to get any colour they like by judicious mixing of each colour's intensity.

I'll throw another "it depends" in here too.  ETC has had excellent success with the RGBL mixture in many of their product lines.  While adding discrete color elements to an array never hurts, it's only one factor contributing to how "good" a fixture's output will be.  Other factors such as CRI, refresh rate, and low-level performance play just as big a part as how the manufacturer chooses to mix colors.