Auditorium House Light Lamp Replacement Advice

Stan Longhofer

Active Member
We are getting ready to replace the lamps in the house lights of our high school auditorium. We considered replacing the fixtures with an LED system, but that seems to be out of our budget right now. So for now we are planning on replacing the existing (mostly dead) halogen lamps with new halogen lamps.

Before we pull the trigger, should we consider replacing them with LED lamps instead? Details of the current install are below, but my concerns would be (1) will we have a good dimming with LED lamps in conventional fixtures, and (2) can we even get LEDs that would have the same specs (lumens, color temperature, etc.).

Details on current install:
  • 30 Pendant fixtures (Rambusch PD-60-250Q) with 250w USHIO frosted mini-can screw base lamps (E11 base, T4 shape)
  • 18 pendant fixtures (Rambusch PD-60-500Q) with 500w USHIO frosted mini-can screw base lamps (E11 base, T4 shape)
  • 26 track mounted fixtures (Rambusch BL-SA-300/500-Par56-IY) with Par 56Q 500w 30 degree WFL lamps (G16d base)
These fixtures are wired to 18 different 20-amp dimmers. If we found the right LED lamp replacements, I've been told we could re-seat these circuits to use only a few dimmers, and that this would help with the dimming curve on the LEDs.

Labor is the biggest cost of replacing the lamps because of the difficulty getting to the fixtures (there is no way to bring in a large boom lift.)

My questions may be moot, because I've not been able to find LED lamps that would fit these fixtures with anywhere near the same lumens. But perhaps all of you will have better suggestions for me, and I wanted to ask before we spent the money on halogen replacements.
 
LEDs lamps that would fit and put out a similar amount of light are just not available. If you want to extend the life of the halogens, don't run them up to full brightness. Keeping them dimmed 10% will imultiply their lifespan by several times.
 
These would come close to meeting your requirements: http://www.cantousa.com/retro/ I have seen them with the typical mini-candelabra base. I believe if gave them the above details, they could quickly give you a quote and explain modifications. These should make rewiring necessary. Near very good dimming - IIRC they pop on a little after a long time out; and they may not bump black out - like the last 10% is a quick fade. Or they may have overcome those shortcomings. And they were pricey when they first came out.

Not sure they can do the PAR in the track, but that rambusch fixture was nearly the standard in theatres and churches. I laid out and specified hundreds, before the ETCS4PAR, and I know they do those. You will have to access to install of course.

If you contact them, please report what you find out. I know my research is a couple of years old.

PS: Possibly some thought required if some of these are used for emergency.

PSS: Simplest replacement would be ETC GDS cylinders and their wireless mesh system. Great performance. Pricey still. Any other replacement I know of requires wired data - not awful but another impediment.
 
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Thanks for the suggestion. I will investigate.



By this I assume you mean that we would need to re-seat the circuits at the dimmer rack, not that we would need to re-run cabling to the fixtures themselves, correct?
You could just relamp. I am inclined to believe these would work as well 2 or 3 to a dimmer as they would loaded onto fewer dimmers, but worse case, yes, intercept the circuits and combine now many separate circuits to fewer. These are not your ordinary LED retrofit.
 
On a different thought process, keep your existing houselights as halogen, and get a couple big LED worklights and use those when there's no show going on.

In a large theatre I used to work in, there were almost 1000 Tivolite bulbs (before they were LED) so they were very strict about when the houselights were used. They had 8 scoops that were used as work lights and rehearsal houselights and the real houselights could only be used when there was an audience.
 
On a different thought process, keep your existing houselights as halogen, and get a couple big LED worklights and use those when there's no show going on.

In a large theatre I used to work in, there were almost 1000 Tivolite bulbs (before they were LED) so they were very strict about when the houselights were used. They had 8 scoops that were used as work lights and rehearsal houselights and the real houselights could only be used when there was an audience.
That's a great idea, but in this case the auditorium is in fairly constant "audience" use with nearly daily school activities.
 
"There's never enough money to do it right, but usually enough to do it over."

For a heavily used space I recommend waiting til the funds are available. Schools have enormous budgets but many demands on those $. It all a matter of priorities.
 
I am also in the process of attempting to go to LED and it is a long slow process. Changing to LED bulbs I think will create a problem with dimming in and out I have found that most of the LED bulbs that I have tried drop to about 30% then flicker to 0. And the problem coming up has been nothing until about 40% then have a tendency to pop on. Attempting to find the right profile on the dimmers has been very problematic because of the age of the dimmers and the system.
 
Speaking as someone who opened his big mouth and requested that my school district replace the existing PAR floodlights with LED...don't do it. Unless you have done the research (which I did) into which dimmable LED you want them to use. My problem is that they either didn't get that message or chose to ignore it in favor of something cheaper (more likely the case). So now, if I try to dim my house lights, we get seizure inducing flickers as the lights dim. Since I can't ask them to change it back for quite a while, my workaround was to build a light cue that shuts off each row in sequence front to back and then fade the side sconces (which are still incandescent). It works, but lesson learned.

The reason I opened my big mouth is because our auditorium is a high-use facility and people constantly leave the houselights on well after they are done which resulted in constant burn outs. The district could only come out 2x per year to replace lights and it was a labor intensive task that involved scaffolding being moved around through the stadium type seating. That was two years ago and haven't had to call the electricians since, oh well.
 
Welcome to Control Booth to both of you @Nigel Romeril & @James K

As you can see from this thread, (and several others if you search a bit) you are not alone and there are no perfect solutions. There are a few bits of advice that are repeated on all the threads:
  • Demo, Demo, Demo
  • Do your research - here and elsewhere
  • Dimmers matter as much as the lamps
  • Avoid line voltage dimming if at all possible
If you post further I hope you can be specific in your issues and equipment. We have a vast depth of knowledge here and if anything we are too eager to share. ;)
 
These would come close to meeting your requirements: http://www.cantousa.com/retro/ I have seen them with the typical mini-candelabra base. I believe if gave them the above details, they could quickly give you a quote and explain modifications. These should make rewiring necessary. Near very good dimming - IIRC they pop on a little after a long time out; and they may not bump black out - like the last 10% is a quick fade. Or they may have overcome those shortcomings. And they were pricey when they first came out.
I did contact CantoUSA and this does sound promising. Here is a link to a playlist of some retrofits they have done: https://www.youtube.com/channel/UC3IcSoY3PYPgZlOaeTKQoSg. When I asked about the dimming curve of the lamps, their rep said that it is extremely good on the down fade, but a slight pop on when fading up. This is exactly what I see in the demos in the video. We are getting measurements for them to send us a demo lamp and see how it works in our space. I will post an update as I have more to share.
Speaking as someone who opened his big mouth and requested that my school district replace the existing PAR floodlights with LED...don't do it. Unless you have done the research (which I did) into which dimmable LED you want them to use. My problem is that they either didn't get that message or chose to ignore it in favor of something cheaper (more likely the case).
Fortunately this is a private school and the decision makers are unlikely to go with something other than what I recommend without thoroughly discussing it with me. They fully agree it's better to wait than to make a poor decision.
  • Dimmers matter as much as the lamps
@RickR, I'd appreciate any additional guidance you could provide on these two points relating to our situation. This proposed solution from CantoUSA would use our existing line voltage dimming system (a Capio Plus IGBT Dimmer Rack). As I mentioned in my original post, we would expect to re-seat several of the existing circuits to common dimmers because of the reduced load from the LEDs (probably drop from 18 dimmers to 5). Is there anything about my overall setup that might make my results differ from those in the demo videos? Just trying to learn as much as I can. Thanks.
 
@Stan Longhofer my points are intended summarize the other threads to get the new folks on their way. You sound well on your way, but here are my thoughts.

IGBT dimmers are a big part of 'dimmer matter.' They are radically different than traditional SCR dimmers. Double check if you actually have IGBT dimmers, or SCR dimmers in a rack that can take IGBT modules. If you don't have IGBT modules you might want to look into finding some. In general, every technology and even every manufacturer does a few things differently that can impact the results. Look into the Capio manual carefully to see what settings you have available. And talk to your lamp manufacturer about the best settings.

Typical line voltage dimming generates issues at low levels when the AC sine wave has been chopped into tiny blips, well spaced apart. LEDs need DC, so some form of electronics is required. LED driver electronics generally react poorly to limited power and time without power. Since LEDs respond instantly to power changes you can see these changes. This erratic waveform can also generate bizarre conditions on the line. Enough so that some lamps will fire and suck the power down for others. I've seen some very pretty strobe/flashing patterns from high quality lamps on a high quality theatrical dimmer. Additionally every lamp manufacturer uses different components and sometime changes them within a product run. The lamp that works today might not be replaceable in 5 years. In short it all gets rather complicated and unpredictable.

I've only seen the predecessor to the Canto product but it was the best retrofit 'lamp' I've seen. It used huge induction coils and probably some other tricks to smooth out the wave form mentioned above. It took several seconds to 'charge up' and so didn't turn on quickly or respond quickly to changes. It also took a while to fade completely out. For house lights these aren't horrible side effects. Last I knew they were also nearly as expensive as new architectural fixtures, that can take DMX or other signals and dim flawlessly. Get a quote on some Gotham Incito or Prescolite Megalum or similar fixtures.
 
Rick points up the one concern I'd have with the Canto - it might be nearly as expensive as replacement with LED fixtures. In the size you are looking at, its probably a $600+ fixture, plus the work to remove and install plus the work to run data plus the need to probably intercept the circuits and provide constant power (probably 2 circuits) plus longer down time plus whatever else I forgot. Frankly, I think its hard to calculate the true final cost BUT, if its close, go with the replacement fixture. Maybe not 10 years but 15 or 20 I think it would be worth it. A new fixture will have a little better control and will be more efficient.

Like Rick, I like the Gotham Incito as a good price/value piece, but in last 6 months or so I have seen others that are as good in this price range - say $500-800. At a $100+ ETCs GDS is very good and I would not shy from Altman's Chalice or The Light Sources HL - house lights designed and built by theatre people.

Good luck.
 
Thanks for the follow up @RickR. According to the manual with our dimmer modules:
Capio Plus Modules offer solid-state performance and unsurpassed benefits. Eight unique models allow for control of almost any common architectural or theatrical lighting load. Each module utilizes patented IGBT dimmer and on-board microprocessing. This solid-state dimming technology operates more efficiently than traditional SCR dimming technologies, and allows for quieter dimming, increased lamp performance and life, reduced heat/size/weight, and lower harmonics.​
So it sounds to me like we are a step ahead in this regard.

@BillConnerFASTC, i’ll let you know what the costs are when I get them. The estimates that we’ve been getting to replace all of the house lights with new fixtures has been in the $80,000-$100,000 range.

Thanks again for all th good advice.
 
That seems like $1100 to 1300 per fixture - probably fair. But in comparison, there is a cost to install the Canto lamps; and the ne fixtures installed probably covers warranty work for a year or two. I don't know how you calculate the cost to access one or two fixtures with the Canto retrofit lamps - even if Canto offers a replacement for free.

Just trying to lay out all the lessons I've learned - including a few I caused. Just saying, even at half the price, you might second think the third or fourth time you have to pay for getting a person to a light for a loose connection.

You know, I just remembered the Rambusch PD and RD series were pole relampable. It was not bad up to 205' or so. I assume you know that. I don't know if they still sell the poles for the T4s or not. (And now you'll tell the pole relamping blows.)
 
Thanks for the follow up @RickR. According to the manual with our dimmer modules:
Capio Plus Modules offer solid-state performance and unsurpassed benefits. Eight unique models allow for control of almost any common architectural or theatrical lighting load. Each module utilizes patented IGBT dimmer and on-board microprocessing. This solid-state dimming technology operates more efficiently than traditional SCR dimming technologies, and allows for quieter dimming, increased lamp performance and life, reduced heat/size/weight, and lower harmonics.​
So it sounds to me like we are a step ahead in this regard.

Sounds good, but I'm a stickler for details. Some versions of the Capio used SCR modules, so a look at the actual modules would be prudent. At that point it would be critical to talk to Canto or whoever you pick, that's where my expertise falls off.

@BillConnerFASTC I'm imagining a Canto Retro on the end of a relamping pole. I think anything over 10' scares me! And that assumes you can pull the trim off with the pole.
 
You know, I just remembered the Rambusch PD and RD series were pole relampable. It was not bad up to 205' or so. I assume you know that. I don't know if they still sell the poles for the T4s or not. (And now you'll tell the pole relamping blows.)
Pole relamping!?! That would be a game changer. The fixtures, however, do have lenses/filters that you have to pop up to reach the lamps. Should I call Rambusch to find out more? They don't show much of anything as far as technical support documentation on their website.
 
That seems like $1100 to 1300 per fixture - probably fair. But in comparison, there is a cost to install the Canto lamps; and the ne fixtures installed probably covers warranty work for a year or two. I don't know how you calculate the cost to access one or two fixtures with the Canto retrofit lamps - even if Canto offers a replacement for free.

Just trying to lay out all the lessons I've learned - including a few I caused. Just saying, even at half the price, you might second think the third or fourth time you have to pay for getting a person to a light for a loose connection.

You know, I just remembered the Rambusch PD and RD series were pole relampable. It was not bad up to 205' or so. I assume you know that. I don't know if they still sell the poles for the T4s or not. (And now you'll tell the pole relamping blows.)
@BillConnerFASTC Pole re-lampable "not bad up to 205' or so". Two hundred and five feet of pole length?? My God, toting and paddling your canoes must've given you the arms of 'Pop-eye'. Two hundred and five feet! I am truly impressed.
Toodleoo!
Ron Hebbard
 
20-25'. Sorry.

That lens or glass disc was designed to tile or rotate and allow pole relamping. I was very familiar with it when tungsten halogen was the new thing. If you can get close to one see if it won't tilt on a kind of center axis but stay captive.

And if you call Rambusch, ask for someone that's been there a long time.
 

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