DYS lamp light


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Hey, my school is doing a production first week of december. Our ighting consists of 16 pars, all with the DYS raylight kit. Recently, four of the lamps have blown. What is their approximate life?? Should I be worried about losing more during the show?? I am wondering if it would be wise to try and replace all of them in one go.
i just posted this in the thread "beginner lighting tips needed" because i saw your message there 1st but ill copy and paste it in here too because this seems to be the appropriate place for it.

ok, why dont you rent some lights, most of our lights are pretty crappy, they work but are not great so we have tons of rented source 4s and stuff for our show. if u have the budget bring in at least a couple more lights to keep from ending up in a "mell of a hess"
no budget....small private Christian skool, we just spent $963 on costumes (I think that is the exact number) to rent them all for two weeks. At most I might could use my own money to rent another par or two, but because of the wiring in the building I would have to run my own extension cables from the truss to the booth, then use some homemade dimmers...I think I'm just gonna have to tough it out...the show will go on! :) it will work without a few lights, we will relamp those four, and I'm hoping my director picks up ATLEAST two extra lamps....I can change them out fast during intermission if we lose some in the middle of a show. And, most of the play will be unaffected, it's just Act II that' I'm worried about. If I have 4 lights and I lose two, depending on what two they are, I'm screwed. :) it's all good though!
If you guys ever find the budget, I would purchase some real PAR lamps. They should fit right in after you take out the reflector. I think it's cheaper in the long run because those lamps last much longer than the DYS because it is protected in a capsule.
not only that, they have a wider beam spread! I would LOVE to get real PAR lamps in them. :( even more, I would love to get some Fresnels and Leko's as well!! ! :( soon, like in a year or two, they will be building their own building, as it is now we rent from a local church. Then, they can build a better theatre. :)
If you can see it coming, then I would take steps to prevent it from happening. If you have the resources, then I would change the bulbs you think will be a problem.

For example, last night, during rehearsals, one of our house lights exploded. It was pretty neat, actually. So now they're changing every single one of them just in case.
I think that your concerns hinge on a couple of factors.

Firstly, as you point out, lamp life. There are a number of different lamps that you can buy to put into a ray light reflector, so unless you know the type that you are using, you can only make a rough guess.

Secondly, and more importantly (I think) is the fact that unless each lamp has done (roughly) the same amount of hours, then you will have some difficulty in estimating when a lamp is going to go. Were they all changed at the same time?

Another consideration is that lamp life is not an exact science and you can always expect some lamps to blow before their life limit is reached. Similarly, some will go past their time.

Given that you have a limited budget and a small amount of fixtures, you may want to replace the lamps in the cans that are essential. I think that you refer to needing four lights for Act II.

I would be interested in hearing about your homemade dimmers as well.
If the wad of production budget was as it would seem spent on costumes, and I take it by the way this was presented you don’t agree with this, due to your concerns about replacement lamps or having enough lights for the show; perhaps nothing will settle the problem for your distribution of the budget on future shows better than having half the stage go dark but some darned fine costumes on stage. Seems like your production crew needs most to work on getting itself people that can sew.

Granted this thought of letting it happen is not fair to the production at hand, but you using your own money to solve the problem is certainly not the solution either. Do not rent, put your own money into or make home made equipment for shows no matter how simple the solution might seem. Realize that should something go wrong there could be more problems than just the lights going out. We are talking both the production’s and possibly your parent’s liability in addition to the cash you laid out for something that is part of the production expenses. You must keep your own cash separate from that of the production, it while seemingly a simple and easy solution is not a good one for you or your program. Trust me, it’s a bad habit to get into.

Do what you can as you should already to have a backup plan ready for during a scene such as someone that knows that if the stage goes dark, they hit the house lights or something like that if your production can’t afford to re-lamp with new lamps in insuring they hopefully won’t go out. Given your production is already buying four lamps, short of a electrical problem, you will already have at least four fixtures you can depend upon working. As you say, you will make the best of it and that’s about all you can do for now.

So a question now. If you are renting from this church, I assume that the lights you are using are part of the rental package. Given the fixtures belong to the church and are being rented to you in a condition that works for the length of your rental, why are you buying lamps much less worried about buying extra ones?

In any case, I expect we all understand already about the choice in beam spreads with the more expensive PAR lamps and that they would be preferable for design purposes - just not available. While some ray light lamps are available in wider beam spreads, their use is less common because the ray light lamp has nowhere near the life of a PAR lamp. 75 hours verses 2,000 hours. What makes ray light lamps seem cheaper to initially purchase and use in fixtures by way of replacement bulbs is in reality a very expensive alternative in the long run. Unfortunately it’s not something that most sales people will advise in making the sale of more fixtures over more expensive ones on start up cost.

Given about an approximate price of $25.00 for a PAR 64 lamp lasting 2,000 hours at 120v, and a DYS at say $6.50 each but only for 75 hours at 120v, the Cheaper in start up cost DYS lamp will cost $173.00 in gaining the same amount of lamp life as one $25.00 PAR lamp. Might present this figure to the church.

As an alternative to just replacing the lamps in the fixtures with the same lamps, given your production is buying them, I would recommend your production either buy PAR lamps, than perhaps keep them for use on your productions, or start buying some DYS/5 lamps which should be about the same cost as a normal DYS lamp. The only change to the in theory 500 hour lamp is that instead of 120v, it’s rated for 125 or 126 volts in further extending lamp life at the cost of intensity and output. I don’t have pricing on these lamps but normally if it’s only a change in the voltage rating the price stays the same. Perhaps for next production, the lighting budget can be given say $100.00 to purchase four lamps for use in your productions. Might be a reasonable enough thing to ask for.

Note, this is given the PAR 64 fixtures have lamp bases that will hold a PAR 64 lamp base. The newer styles of ray light lamps have the same base on them, the older ones only had wire leads on the rear of the ray light reflector and such cans would not have the lamp base in place for you to install a PAR lamp into.


Mayhem has a important point about the unpredictability of estimating lamp life when under the control of a dimmer or even line voltage when it’s different than the rated voltage of the lamp.

For every 1% difference change below the rated voltage of a lamp, it’s life is extended by 13%, it’s output is decreased by 3.6% and it’s color temperature is decreased by 0.4%. These factors are inverted with over voltaging instead of dimming.

In other words, if you take a standard DYS lamp, given each individual lamp will have it’s own individual closeness to the specification, it will last on average 75 hours, have a color temperature of 3,200°K and output of 17,000 Lumens. Especially dependant upon brand to brand comparisons, black sheep of lot numbers, and one lot number to another will also alter these average figures.

Given four lamps, dim lamp one by 50%, lamp two by 25% and lamp three not at all from it’s rated voltage of 120v and you already have lamp one expected to last 487.5 hours, lamp two to last 243.75 hours as opposed to lamp three still equaling 75 hours. In the same respect however, lamp four the 500w PAR 64 lamp would last 13,000 hours at 50%.

These rates the lamp is dimmed at is however during shows constantly changing along with other factors onto them such as dimmer trim levels, voltage spikes and even cold start turning them on than off. Once you change that dimmer ratio, you completely throw off the expected life again into something almost approaching random but at least say six times the expected lamp life. - My guess.
Also since it’s on a dimmer, the voltage at the fixture will only rarely be at the 120v given this is the power feeding the dimmer. Factors like voltage losses due to the dimmer and voltage drop will in most cases drop the voltage from two to ten volts. This lamp is rated for thus 75 hours at 120v, but given a at full power to the lamp being 118 volts, it’s already at about 125 hours in life even if left on full.

Get confusing??? There is other factors still including bad lamp bases, dirty lamps etc that will also effect lamp life.
I thought that the voltage output from a triac or SCR dimmer was constant and it was the frequency in which the lamp is turned on and off that produced the dimming effect. Or are you referring here to the use of a rheostat dimmer?
The SCR dimmer eats up voltage in electronically chopping the dimmer curve or in the case of at full voltage, still controling it. A rheostat will when at full be an open switch almost and have much less resistance to current flow thus be almost the same as the line voltage.

In other words, or at least from my understanding - given dimmers are not my specialty, the voltage at full will be constant (without chopping - depending upon the trim setting) but still less than line current feeding the dimmer. No doubt this is very much dependant upon the dimmer type also.

No matter the case, it's fairly rare you will see a full 120v at the fixture after it travels down a mile of cable. Our voltage drop losses are much larger than yours are on the same size wire don't forget.

This is also why most of the more modern stage and studio lamps are burning at 115v instead of 120v anymore. While still operating over voltage, it's still close enough to the rated voltage of the lamps to use the hotter burning lamps.
Didn't consider the difference in voltage drop but my comments were based more upon the mechanism of dimming ie, rapid switching of the lamp in the case of triac or SCR dimmers.
wo.....I NEVER had ANY clue about the differencee in lamp life!! I just emailed our director, she was planning on orders more lamps today, I asked her to order pars instead, I don't nkow if she will, or if she has already ordered the DYS...I do not know if he school or the church pays for the lamps....in the past, most of our costumes were made by us, this year they wanted the lead characters to be in basically tux's and the lead ladies in fine dresses, beyond our capability. No, the budget is not equal. We payed for the costumes mainly with wednesday hot dog lunches.

the church has several home made dimmers, I don't know what for, I don't use them for aything. They are likt eh kind you would find in the wall of a house for dimmming their fan light or something. And my own money in the show? I have bought several blue lights to use, but I am planning on keeping them after the show so I paid for them. I am also planning on bringing my blacklights in because I want our glowtape to glow really well in some areas--just stick a blacklight by it, it will glow like the dickens! :)

Ship, one more question: do fast chases hurt lights? Lets say I warm them up first, then launch into a really fast on-off chase. Am I reducing the lamp life??
Chases dependant upon the dimmers don’t hurt incandescent filament lights when they are on a pre-heat trimmed circuit dimmer pack. What most hurts lamps is from going from true zero to full. In the case of most - and I mean most at least stage ready gear, is that they have a trim setting for the say 0-80% or 20-100% dimmer pack range. When trimmed properly with such a range in dimmer that shows 0-100/FF, but is only within 80% of the range of the dimmer, you are assured of a lamp that’s either receiving sufficient voltage as a pilot light circuit that it will warm the filament so it’s not shocked by jumping to full. Or it’s adjusted so that by going to full, it still is not at full in preserving some form of lamp life. Normally the dimmer will be trimmed so that it is at about say 13% when showing 0% on the dimmer. This best balances dimmer pre-heat of the lamp and lamp life in not maxing out it’s voltage. It also means at such points as the end of the night yes you are better off in turning off the dimmers. Dimmers first, light board second is the rule. In any case, when the lamps are warmed by a normal dimmer pack, they are not shocked into going to full at least. Granted you will no doubt have some loss in strobing them, overtly in something you can trace as an effect given a well trimmed dimmer pack, it’s not going to be a lot you can note.

Now short of a theater style dimmer, is strobing the lamps going to effect them? Yep, going from cold to very hot will tend to destroy metal and that’s about what we are talking about here. Once the lamp starts to get warm or becomes a minimum temperature such strobing won’t much effect the already warm filament and you are free to strobe at will. A really fast chase won’t effect a lamp much than both in necessary amperage to heat the filament to the wattage required in possibly blowing a breaker or lamp life signifigantly.

Remember however that the larger the filament size - not always related to wattage, the longer it will take to heat up the lamp. In strobing lamps, you tend to want very short life lamps which often have the smallest filament wire or length of wire in making it burn very hot but not last long in life. A Photo Flash say 150w bulb will than flash with it’s small filament but short life much faster than say a basement’s 150w normal incandescent bulb. A PAR lamp with it’s huge filament will flash much slower than say a Leko Lamp, much less even say 25w incandescent normal lamp. All a question of filament length and thickness. Which is going to strobe first for instance, a 6" Leko with EHD lamp or 500wPAR64 MFL lamp? Look to the filament description to tell you about the speed that filament will strobe given this. The longer or larger the wire, the longer it takes to heat up. On the other hand, the at least wider the wire, the more resistant it is to heating up quickly or various other shocks to it’s life.
aww man.....

ok, I have mentioned before that no one knows where the dimmer packs are, right? well, one truss of the lights (4 of them) is not working. 3 of the ights were out, figured the bulbs were blown. Then, the 4th stopped. Ok, bulb blown. Nope. It came back on a little while later! Then, it went back off. Then, came back on! According to my light guys it's doing that. Great. I haev a problem in the system and I don't know where. It could be in the fixture itself (it makes me wonder if any of those 4 lamps are dead, if in fact there is just some problem with the dimmer) or in the wiring, or in the dimmer. The problem with the dimmer could be something I can fix, or not. I have to go climbing in the rafters to find the dimmer packs now. :( argh.
jahjah i had a problem that is kind of the reverse yesterday, i had a lamp that would not turn off. i dont know if we ever fixed it or if we just unplugged it and pluged it in to the next open spot on the dimmer. w/e ill check on monday.
I know we use NSI, what do you have?? We used to have many channels that would not turn off or dim. The channels were bad, we took them in and got them fixed. There are like two parts on them apparently that go bad and they replace them and boom, they work fine again! :) (oh, this was at my youth group, that we got things fixed....my school happens to have an NSI system too)
Dmx tester!

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