Lamp Questions

I figure that this should go here instead of starting a new thread: What are the lamps that work in the Altman 3.5Q ellipsoidals? What is the highest wattage (they say 500 watts, can you use a 575W lamp)? Which lamps are available in long life (1000 or 2000 hour) models? Thanks in advance!
Been using HX-600 lamps in Altman 3.5Q5 fixtures since Robert Altman sent me a care package including one that was Pre-market along with some other stuff due to a letter of complaint I sent Altman in while in college and needing some parts for a store front theater show’s lights I was attempting to fix at the same time as the Shakespeare was coming to market. Big rush at Altman to get the fixture out in time for that year’s LDI (or was it USITT) thus some small theater’s need for parts to fix a Leko or two fell to the wayside until LDI was over. Robert Altman personally called me in my dorm room in finally getting me between classes to apologize thanks to my snail mail letter. Needed these parts to get one more Leko up and running, they didn’t come thru. I was but a in college punk kid still in comparison to the owner of a lighting company that had won the Widget of the year for the lamp he just finished all effort in designing. Yet the guy still took the time to apologize personally, make rights the best he could and help this college kid understand the concept of such new third geneation Lekos he was in part a key in bringing to market. The theater is a small world and works both ways. Never step on toes but fully expect or try for the world at all times.

No, I never went fishing with the Altmans, and I heard later about some train wreck of Kliel gear that was bought and stamped with the Altman name so as to start the company, yet as a college kid, I was life long impressed that this person might call my dorm room and chat with me more than just a few minutes about theater tech. Speak what you want about the gear - any gear, but person to person, this industry is very small and all in it are as one when it gets down to it. This no matter if owner of multi-million dollar company or college kid between classes talking with him on the phone by way of apology call.

He sent me extra lenses and parts for the fixtures and a original Thorn HX-600 lamp to tinker with. I given this lamp was almost as cool as the guy I went to school with who had a medical grade laser of his own in his dorm room. This was in the days where ISU had put on order like 10 or the original S-4 fixtures but were on a 6 month waiting list for them. Such a HX-600 lamp was totally killer for both show and tell at school and in projecting light out of my dorm room window by way of me taking fixtures home at night from the out of school theater so as to fix and re-wire them. This was what... 1992? Been using the 575w/115v lamp in the 3.5Q5 in them since without any problems. Such lamps will tend to with time burn up your low/normal temperature lamp bases over that of a 500w/120v lamp. Easy enough to replace once it goes bad and standardized in going the more modern high temperature lamp base. Never had a instance over the last what 13 years that a reflector has reacted badly to the lamp or any other parts have problems with it.

This said, the fixture is rated for a 500w lamp. It is UL listed for a 500w lamp - normally a EHD or EHC. Your liability insurance might demand that you use only lamps rated for the fixture. Also on the FLK lamp while I have never had a problem no matter the brand, others I respect won’t buy some brands and in general have found on this lamp all it takes is a good bump and the lamp’s filament breaks. The HP-600 or HX-600/FLK isn’t a very rugged lamp, kind of just high output in being first or following (history is confusing who did what first) the HPL lamp. These are third generation halogen lamps - I would not buy the HX-600/FLK these days. Fourth generation Leko lamps are out there to use instead.

I have never had a problem with HX-600 lamps in this specific fixture now ANSI designated as a FLK lamp. Yes over the years and especially in the past year one by one given the fixtures are at least 15 years old I did replace lamp bases in going high temperature modern ones. I consider that proper maintenance and life of a fixture not overall heat damage to it.

A few years ago, Osram came out with the HPR 575/115v lamp, (it’s a sleeper of a lamp in being one not many use and might some day become discontinued.) I was sent a free play test one by way of filling out a internet survey at the time they were introduced so as to play test it. This is a lamp based off the HX-600 lamp but with a internal reflector that sort of completes the ellipse of the reflector in adding 15 to 20% more light output. Popped it into a 3.5Q5 fixture and have never gone back to any FLK lamps or other types other than when I went HX-400 and HX-401 for the fixtures in a lesser output need for fighting amber shift.

The HPR lamp in a 3.5Q5 right next to a 50 degree S-4 Leko will have a beam of light you can see inside the beam of the S-4. The HPR lamp kicks the butt over that of a HPL. Have not put a “heat sink adaptor” on a HPR and tried it in a S-4 Leko but overall it’s a much more output lamp. The HPR lamp for high output use does away with the famous “Altman dark spot” normal at times to the center of any 360Q based fixture center of the beam. (The 3.5Q series is for all intensive purposes a 360Q series fixture.) Just a totally flat field of very intense light by way of output and a much flatter field of light one can see inside the beam of a S-4 Leko. Did a show where I compared a 3.5Q6 to a 36 degree, while perhaps not correct on beam angle, the punch at 60' out of the 3.5Q6 for a wash topped that of the S-4 Leko also given the same wattage of lamp.

It also did a better job of pattern projection but that’s suspect to more study. If you have the money for a 300hr high output lamp, that’s the lamp of choice for such a fixture. Just had my local theater buy up my old 3.5Q5 fixtures. They when lamped with the HPR outclass or at very least equal the output of the more modern third generation Shakesphere with GLA lamp installed.

The GLA series of lamp is the once HX-602 and HX-603 or was that HP-601, HP-600, HX-604 or HX-605? Depends upon what source you buy such lamps from in what they converted once HX or HP series to the new GLA and GLC standard of upgraded HX-600 lamp. Some of this HX series was once the 230/240v lamps - just hard to lock down which they were. Granted also that Phillips (possibly the best of this lamp type) say they invented the GLA/GLC and are a unique design and not based of any experimental GE/Thorn HX/HP lamp code. (Even once bought some 120v HX-603 lamps which are no longer on the market. Good lamp about equal to that of a Phillips GLA.)

Note. Any lamp starting with a “H” no matter if HX, HP, HPR (reflector), HPL or what ever is not a ANSI recognized lamp. ANSI standards dictate that for any one lamp that’s industry standardized and compliant while there is a range of compliance will have certain common features. This especially wattage/voltage. A HPL lamp can never be a ANSI lamp proper given the variations in wattage, lamp life, and voltage under the same letter code. The ANSI system to the best of my knowledge also stops at the letter “G” at this point and will probably skip over “H,” “I”, and “J” (J given the “Japan Code” a separate topic. Expect future ANSI lamps no doubt to start with “K” in the three letter nomenclature.

The GLC lamp is the high output lamp that’s got a much smaller filament size than that of the HX-600. It’s also a more rugged filament. This is the lamp dejure of the non ETC based light fixture. Small compact lamp filament somewhat similar to that of the HPL and will do pattern projection well due to it’s small size. For pattern projection, one is probably best using a GLC over a HPR due to the more point sized filament. Otherwise I would stick with the HPR for more basic high output work at 575w/115v.

The GLA lamp (especially from Phillips by way of at least a few years ago published lamp specs on the output as being the best - all no doubt similar by now, but GE/Osram/Ushio also make it) is the king of the 575w/115v long life lamps for any modern G-9.5 medium bi-pin lamps these days for long life cost effective use. Let me say this again, the GLA lamp is the best use for all uses by way of balancing output and lamp life. All schools should be using it for the base of light where not special or pattern in a Leko or modern non-ETC based fixture from L&E “Runt” to even HES Color Command can work with this lamp. This no matter if 360Q, 3.5Q, S-6 Shakespeare, SL from Strand, or even most color mixing type PAR fixtures. Very universal lamp type when not paying ETC for use of the HPL series lamp. Had a request the other day for some HX-401 lamps or by way of American DJ S-4 clone PAR speak, what once was listed as a HPL 375/115 lamp by way of them is now more accurately not able by way of patient infringement - not using any HPL lamps. The HX-400/HX-401 (Thorn/GE and Ushio) is also a very good lamp type and just as efficient.

Good and rugged stable high output lamp. Years ago I tested one Phillips GLA with a (discontinued) Thorn HX-603 575w/120v against some EHG lamps. No difference perceivable in testing. (This given those doing the play test for me were not as observant as I will have hoped.) They did start converting their HX-600 based 360Q inventory to GLA lamp on the other hand and have never gone back even with Wiko/Eiko HX-600 lamps being dirt cheap on the market. Wiko as I still call it, now Eiko should have no dogma associated with the brand name, they are quickly joining the club of Premium brand in lamp supplier. For now, often lower prices in lamp is something to consider in say going FLK/HX-600 if much cheaper as opposed to say FLK proper or perhaps GLC proper, or even HPR for high output. FLK/LL as not a proper ANSI designation but advertised as such or more proper HX-601 which would be a long life 575w/115v 1500 hour at 115v version of this lamp could work fine as opposed to a GLA proper HX-603 lamp. It’s a second generation 360Q based light fixture in the case of a 3.5Q type, it’s very possible in going long life third or fourth generation lamp that you won’t notice the difference in type in all being more efficient than that of a EHD.


For the 3.5Q series of fixture, even with more modern high temperature lamp bases and if it’s using the same lamp cap as that of a 750w rated 360Q fixture, I would not go over 575w/115v on a lamp for it. Sure, I know of some 1.2Kw lamps that one could pop in the fixture and there still might be the internal reflector based 1Kw FEL on the market from Osram still, but it’s a small light fixture and will no doubt not have the cooling cubic space sufficient to work with over a 575w lamp. Never tried it, never no doubt will unless in a situation where the light only needs to be on say under a minute in duration. At that point, the amount of heat generated by the lamp in going up to full and really warming up will be of question in what works could work.


In the end, the Osram HPR 575/115v internal reflector lamp should be considered the best high output base of light lamp available on the market for such fixtures. The GLC lamp than after that should be considered in play testing with the above for pattern projection as potentially better for this due to it’s smaller filament. In long life 1500 hour lamps (by way of specification rated for 1500 hours at 115v) the GLA lamp is the best lamp to go for. I’m prone to the Phillips version but have not updated my notes on other brands becoming as efficient recently. AT some point also efficiency in better output is price based. If you can get a lamp for say $12.00 and it dies before it’s time, as opposed to say a $18.00 lamp that might or might not live as long or much longer, perhaps the cheaper lamp could be more cost effective.

Overall, you have a choice in going 300hr verses 1500 hour at 115v for a long life verses high output lamp. Will you note the difference in lamp life given it’s a lamp that normally will live under the control of a dimmer and at best only spend minutes of it’s life at full output?

That’s the balance in high output verses long life most stages have to consider. Many designers raised in the high output world will desire or demand high output lamps and for such shows they design will be sufficient in profit to eat the cost of were one to track the lamps, such lamps taking a spill before that of a long life lamp which loses some in color temperature and output in exchange for lamp life.

Many designers when not offered both in one lighting rig will never notice the difference. Come in from the bright sunny sky and the stage is dark. Sit in a theater with a bunch of incandescent lights when not compared to that of halogen ones and it’s also bright. Put a long life lamp next to a high output one and yep, it’s dimmer. Same as with 115v verses 120v lamps. It’s at times a wonder that the guys in the 1960's and 1970's were able to see their way in the dark much less design huge improved for output shows given the incandescent to halogen upgrade lamps they were using. Was no doubt much similar to that if not even more so than that of the 360Q series to S-4 upgrade importance in color temperature and output but overall magic has been made on stage in lights being bright no matter the efficiency over the years.

For your 3.5Q fixtures, I would say start with the GLA, and only use the HPR as needed but available. Don’t get spoiled in what’s brighter but not as cost effective. A GLA lamp will last 5x as long as a HPR or GLC. On the other hand, be ready that they will not as a lamp live as long as the EHD designed as a lamp type around the fixture. Yep, the lamps will be brighter now but you will exchange lamp life on a more bright and slightly more frequent repairs to the fixture and lamp changes to balance out what the fixture was designed around. The EHD 500w/120v lamp is fine for some classroom base of light use of a 3.5Q fixture. The HX-400 or better yet HX-401 is also a good lamp. In maxing it out, go GLA and save the HPR and GLC for where it’s needed or where such fixtures will be needed in a balanced main stage inventory so as to complete with that of third generation modern fixtures - and even best them at that. The 3.5Q fixture is often best as a short throw fixture. More light out of it is often not necessary. Very nice to do but a EHD lamp is often suitable as long as it’s not attempting to compete with a more modern fixture.

Hope such info or opinion is sufficient. If not ask more = 3.5Q Altman fixtures are kind of my pet fixtures as with pet lamp style. Once one makes magic with a fixture, it tends to grow on one so give me a break in bitching about a long post. Yep, the 3.5Q series is my favorite type of Leko. We are talking about years upon years of experience with them as stuff I own and where ever possible tend to use.
 
Last edited:
Wow. That was incredibly helpful. My old high school may be getting 3.5Q fixtures for sidelights (they need fixtures with shutters, and picked the 3.5Q b/c of price), and I need to have a lamp to reccomend to them. Cost of operation is the number one factor. If we can get a GLA lamp that is 1500 hours but slightly less bright but replacement costs will be much lower due to lamp life, I'd say that's what we want.

Besides that, I love the 3.5Q fixtures as well, and wanted to know if they could be lamped to 575. Thanks.
 
Buy a Photometrics handbook and while not the lamp in the sepecifications, look at the throw range of the fixture. This is a very short throw fixture mostly. Sure there is 3.5Q12 and perhaps longer throw types of this - never seen more than a 3.5Q8 myself - ever.

This is a short throw fixture at least for me.

that's something to keep in mind if side light by way of normally for side light a 6x9 or 6x12 would have been chosen.

For a used fixture, a 360Q and 3.5Q should be about the same price. In design for side light, I might lean towards the larger lens.

For budget, while smaller size, I don't think I have ever seen a 3.5Q as a side light. Could be done, just never seen anyone do it overall.

Caution also in that if the throw distance is sufficient -given it's side light, perhaps a 360Q fixture once lamped with a more efficient than EHG at 750w, GLD (High Output) or GLE (Long Life) will for throw distance have more "Law of Squares" output put on stage.

Beyond any 3.1/2" verses 6" lens size in base of light to start out with, explain how especially on say a 30' stage how a 750w lamp rated fixture it might as side light be a better fixture to choose than that of a 500w rated 3.5Q fixture as a side light which would overall need to focus either for a distance or for wide angle in making that overall output similar either close up or across the stage. More wattage is important at times perhaps such as this. 360Q or some third generation Lekos might be in 4.1/2" to 6" lens type be more efficient as a side light.
 
I have some strip lights at a local school. I have no idea what kind they are. There are no markings on them at all. They're four circuit and i have no idea what kind of lamp it is. It's a regular incadesent screw in base. The lamps are 120v at 150w, with some type of frosting on the inside. Any ideas on what this is?
 
The EHD 500w bulb is recommended and offers a 2000 hour rated life. An EHG will fit and give you 750w and 2000 hours of life but also eat gel and shutters.

The FLK/HX600 will also work at 575w but you'll be down to 300 hours of life. There are longer life versions of these but you'll lose brightness as life increases.
 
I have some strip lights at a local school. I have no idea what kind they are. There are no markings on them at all. They're four circuit and i have no idea what kind of lamp it is. It's a regular incadesent screw in base. The lamps are 120v at 150w, with some type of frosting on the inside. Any ideas on what this is?

They're probably R40 strips. Are there aluminum reflectors in each cell? If so, they'll take regular old A lamps. If not, go with 120w R40's.
 
Ushio notes that a halogen lamp cools below 250C the lifetime is significantly reduced. Their generalization is that 90% voltage is the lowest voltage suggested for halogen lamps. Lamp Life Calculator- Support

Does anyone have info on how this affects HPL 575 is a Source Four Zoom? I would guess that the voltage at which lifetime starts to fall is less than 90% because the enclosure is keeping the bulb hot and it is running very hot anyway.

I'm looking for a the knee in the %voltage vs lamp-life curve. My lights are always burning out too soon and I need to rent a lift to replace them. Thx in advance
 
...I'm looking for a the knee in the %voltage vs lamp-life curve. My lights are always burning out too soon and I need to rent a lift to replace them. Thx in advance
Are you using the standard or long life (suffix LL or X) HPL lamps? Determining the maximum voltage at the fixture will determine whether 115V or 120V lamps are appropriate.

Information at Mathematical Formulas for Lighting may be useful.

See also http://www.controlbooth.com/forums/...res-long-life-lamps-vs-high-output-lamps.html. If HPL575/120X are not bright enough and HPL575/115 don't have the desired life; it may be possible to to go to HPL750/120X, if the capacity is available.
 
Thanks for the great info, but perhaps I did not explain my question well enough.

The more you dim a standard incandescent light the longer it lasts.
With halogen bulbs this is only true IF you keep the bulb hot enough to stay in the halogen cycle (about 250C). Once the bulb falls below that temperature the tungsten starts depositing on the glass instead of re-depositing on the filiment and the bulb life decreases.

What I am trying to find out is - What is the % dimming of a 2000 hour HPL in a Source Four ParNel or Zoom that will cause the bulb to fall out of the halogen cycle and start to lose its longevity.
 
What I am trying to find out is - What is the % dimming of a 2000 hour HPL in a Source Four ParNel or Zoom that will cause the bulb to fall out of the halogen cycle and start to lose its longevity.

I don't think that there is a real straightforward answer to that question. There are so many factors that play into how hot a lamp stays. Also, percentages are relative and are different for different people depending on the dimmers they have, the profiles that those dimmers are set to, what shape the dimming curve is, etc. You also have factors like ambient temperature, age of lamp, orientation of the fixture, et al. Consider that it makes a difference if you start with the lamp at full and then try to cool it off as opposed to starting at zero and staying below the threshold.

You should also note that if you plugged the specs for an Ushio HPL into the calculator you linked to, it will give you the answer you seek (based on their specs, assumptions, and math). With the lamp you mentioned (HPL575/115X: 2000hr, 12360 lumen) the calculator says that at 90% voltage (where they say the halogen cycle stops) you would be at 71% intensity and 370% lamp life. Ironically, as you work down the chart to lower voltages the lamp life continues to rise, so while operating above 90% voltage may be ideal for the halogen cycle, by Ushio's math it is increasingly more efficient to run you lamp and lower voltages.

On the other hand, while it may be an interesting "fact" to know, what is the practicality of knowing? When are you ever in a situation in this industry where you can say that you have to run your lamps above X percentage to save the lamps. It seems to me that whatever the calculator spits out as an answer should be close enough for all intents and purposes.
 
I guess I am still being too brief to be clear. We have an auditorium which is used for a lot of purposes besides performances. They use one or two presets for non-performance time, and the lights are set to that preset most of the day (12-16 hours) almost every school day. Some of the lights that are recieving around 60-70% of their rated voltage are blowing out in only a few thousand hours. As pointed out, they should be lasting in excess of 370% life, or 7000 hours.

I talked to Ushio and they told me about their 90% rule and appoligized that their calculator does not take halogen cycle into account.

All of your thoughts in your first paragraph about dimmers, profiles and hot to cold or vice versa are good points, showing that I need to clarify my question..

Clarification - I am talking about long term (several hours or more) operation at a measured % of rated bulb voltage on a typical stage (30 degreesC) in a Source Four PARnel or Zoom pointed about 45 degrees down.

The practicality of knowing is being able to go more than a few months between bulb changes.
 
To be honest with you, it seems that unless you really need incandescents in there for some reason (like being able to dim them), you might check out the Source 4 HID version? Its rated for 12,000 hours. I feel like your not going to get very long lasting lamps unless you use a discharge lamp of some sort. At our basketball arena, we have Source 4s with the long life halogen lamps in them, but still not HIDs, and its a pain to replace them no matter how often you need to do it, be it once a month or once a year. How many of these guys do you have, and do they need to be dimmed, or is that for
 
I guess I am still being too brief to be clear. We have an auditorium which is used for a lot of purposes besides performances. They use one or two presets for non-performance time, and the lights are set to that preset most of the day (12-16 hours) almost every school day. Some of the lights that are recieving around 60-70% of their rated voltage are blowing out in only a few thousand hours. As pointed out, they should be lasting in excess of 370% life, or 7000 hours.

I talked to Ushio and they told me about their 90% rule and appoligized that their calculator does not take halogen cycle into account.

All of your thoughts in your first paragraph about dimmers, profiles and hot to cold or vice versa are good points, showing that I need to clarify my question..

Clarification - I am talking about long term (several hours or more) operation at a measured % of rated bulb voltage on a typical stage (30 degreesC) in a Source Four PARnel or Zoom pointed about 45 degrees down.

The practicality of knowing is being able to go more than a few months between bulb changes.

Here is the real thing. If your fixtures are going to be on for 12-16 hours a day, you should see lamps fail on average around the rated life of the lamp. If you get "a few thousand" hours on a 2000 hour lamp then you are in good shape. That would mean that you are only replacing lamps about every 180 days, which doesn't seem so bad. Consider that the rated life of the lamp is based on the average life of some large sample group. Some lamps may last significantly longer while others may fail prematurely. It is an average, not an exact science.

Now, as was mentioned, if the "non-performance" usage of the fixtures is basically for worklight or rehearsal light, just to have light on stage, then you should probably look into some CDM or Metal-Halide fixtures. These fixtures, while bearing a larger up-front cost and higher cost for lamps are more economical over time as the lamp life is excellent and they are much more efficient in terms of lumens per watt. The only real downside is that most CDM and M-H fixtures take some time to warm up to full intensity. However they are a much better match up for a 12-16 hour/day burn time. One of the other great advantages of using CDM fixtures is that they don't need dimmers. Put them on plain old non-dimmed, switched circuits and then you have freed up the dimmers that you were using for worklight!

At my theatre, I do use source four PARs as work lights, and most days they run at full for an average of about 10 hours a day. I expect to have to replace the lamps in them about once a season. We debated going to CDM fixtures when we were looking for new work lights 2 ears ago, but decided to stick to standard fixtures due to the fact that we need the instant on capability of T/H lamps.

So, I would weigh the cost of your options vs what you need to accomplish. Look at whether or not you have more lights on in your presets than you really need. Cutting lights out of the presets will save lots of lamps. Ultimately though, it sounds like you are getting exactly what you should get in terms of performance from the lamps you are using.
 
Thanks, Maybe time for more clarity. This is for a High School (read that, "No money unless you have a great reason and can wait a few years"). I am just trying to make the best of a bad situation.

My plan is to convince the school to install some flourescents /HIDs in addition to the HPLs, so we are only using halogen for performances. However, I need a number for the lower limit of the halogen cycle so I can put it into my model for bulb life and operating costs.

I'm fairly sure the 90% of rated voltage number from Ushio is much higher than reality, some history indicates that 50% of voltage seems to be below halogen cycle temperatures, but I'd like a better number if anyone has one. If not, I'm going to try some measurements with themocouples and IR thermometers, but I thought it would be easier to ask first.
 
Here is the real thing. If your fixtures are going to be on for 12-16 hours a day, you should see lamps fail on average around the rated life of the lamp. If you get "a few thousand" hours on a 2000 hour lamp then you are in good shape. That would mean that you are only replacing lamps about every 180 days, which doesn't seem so bad. Consider that the rated life of the lamp is based on the average life of some large sample group. Some lamps may last significantly longer while others may fail prematurely. It is an average, not an exact science.

Thanks for your thoughts. I understand averages and curves, but at 90% of voltage or less these lights should be lasting over 7000 hours. We are getting nowhere near that. I'm trying to find the reason. Many of the bulbs are in a position where we need to rent a lift to change them. Real pain, no forethought in construction.

I can review almost everything else, but if I knew how low (85%, 80%, 75%, etc. ) I can run the bulbs before I started reducing their lifetime I could set all the presets to not let that happen.
 
The fact of the matter is, the lamps are rated for 2000 hours, and thats kind of where they will fall. I highly doubt your going to ever see 7000 hours out of a HPL, except in some flukey circumstance. Basically, when you run a lamp like that for a long time, it will begin to fail, and then go out. Its a pain to rent the lift, but its kind of going to be the reality unless you get some different equipment in there. Even if you do get right on the edge of the halogen cycle, your still going to see lamp failures fairly regularly. I hate to say it, but I highly doubt there really is anything that you can do about the situation, other than try and convince your bosses that some form of alternative lamps is a good buy. I totally feel your pain, if not worse, as in our arena for aisle lighting they went for the higher output HPLs, and they need replacement every 300 hours. Some of those are underneath the catwalks, and you need to strap in and climb out onto a beam to get at them, or rent an 80 foot boom lift (which there is only one of in West Michigan, but its not available for rental, so you need to go to Chicago to get one). Fact is, lamps die, and part of your regular maintenance schedule is going to have to be replacing them. No one likes doing it, and its often a pain in the rear, but it comes with using high-wattage lamps. Realistically, there is nothing you can do to make those lights extend to 7000 hours.
 
First do not consider halogen cycle not working at X percentage of dimmer on +/- 120v line voltage circuits. Those notes of the halogen cycle effect on halogen lamps where the free halogen gas components attack the cooler parts of the lamp in causing premature failure are for low voltage lamps = under 68v lamps as a concept. This and for low voltage lamps it would seem in other than series condition such as a MR-16 cyc light might see where it's 120v but distributed in series instead of an individual lamp dimmed. (Don't know why but it is the case.) Ask Usho's Dr. Bulb about that concept.

In general at 120v +/-, that voltage is sufficient at any dimmer intensity to make the halogen gas preform properly no matter the intensity from what I'm told in asking manufacturers about this specific issue many years ago. You have a very valid question but it's not the cause of your problems.

To be more specific, how much by way of bubbles in the pinch/globe area do you see in etching and melting away of the glass where the filament comes into the globe of your failed lamps and how many times do you have blow outs there or at the fill pinch? Those are the coolest parts of the lamp and where the free chemicals in the halogen gas attack when board. I would assume other than filament failure, pinch failure is going to be really really rare in your situation which confirms end of life being the cause and not free under voltage halogen gasses killing off your lamps. Remember, each lamp's failure has a cause, study what caused that lamp to fail and you know of a potential problem. Doubt you have many or any monofoil pinch or fill pinch failures in HPL lamps.

Hit up the Sylvania website, do a search for the HPL lamp and cick on one of them. Hit the "Doccuments" section and print up and read the ... forget what it's called but it's about low voltage lamp design in PDF form. All kinds of info about halogen lamp design and details written in a way that if you are ready to learn it's easily understandable. Good PDF for free book. If Usho still has the articles from Dr. Bulb, also good info provided.

Assuming that the effects of dimming your lamps is not playing a role on why your lamps are not living up to your expected lamp life for the lamps we need to look into other things.

-First the voltage at the fixture and that verses the voltage of the lamp used.
-High output or long life HPL lamp, 120v or 115v?
-What's your dimmer trim setting and type of dimmer and control in use at all positions the lights are controlled from?
-You mention other than show uses are at x percentage, how is that done to assure it's not just saying "oh' yes, we only bring it up to 70%?"

Beyond this we get into details about the care for the fixtures. Put a fresh lamp into a bad lamp base it's gonna go bad really soon. Same with cooling and cleaning of the fixture. Not to assume anything but there can be lots of reasons for a lamp including and especially one finger touched or one in a high dust or dirt or fogged environment to go bad before its time. What do the lamps look like in going bad before their expected time?

So at least as a start there are a few things to figure out and check for now in troubleshooting what is causing this problem. Refinement of the above will hopefully solve the problems in such lamps should last in theory at least the expected lamp life time.
 

Users who are viewing this thread

Back