# HPL 575 or 750 in your Source4?



## gafftaper (Jun 14, 2007)

I'm still working on my equipment inventory for the new theater and I'm debating going with HPL 575X vs HPL 750x in my Source4's. I definitely want to use the long life model for budget reasons. I was originally thinking about going with the 750x because it's about the same lumen output as the 575 but 5 times the life (see chart below).

HPL 750 300 hrs 21,900 lumens
HPL 750x 1,500 hrs 16,400 lumens
HPL 575 300 hrs 16,529 lumens
HPL 575x 2,000 hrs 12,360 lumens

On the other hand, it's a black box with a typical throw of 25-35 feet, so that extra punch isn't REALLY necessary. With 750's you are pushing it a little putting three on a single 2.4k dimmer. With 575's you can comfortably put 4 on a dimmer. 575's are cooler for the HVAC system, easier on gel, and easier on gobos.

Now after talking it over with a buddy I'm thinking of just going with the 575x and keeping a dozen standard 750's in stock in case I need some punch for a specific scene. 

What do you use and why?


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## Chaos is Born (Jun 14, 2007)

your looking at much easier on gel... i'm noticing that a good portion of the deep saturated colors don't come in a high temp version... and end up burning through the gel about half way through the show...


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## SteveB (Jun 14, 2007)

gafftaper said:


> I'm still working on my equipment inventory for the new theater and I'm debating going with HPL 575X vs HPL 750x in my Source4's.
> What do you use and why?



My 24 fixed lens S4's are 750 due to the throw (50-75 ft.)

My Pit wash S4 pars are also 750 as I need the punch and don't use color.

My Box Boom and overhead electrics S4 25/50 zooms are all 750 as 1) I want the punch and 2) They sometimes serve as backlights mixed with Par64 wides @1000. The S4 zoom @750 is a great light. 

BUT, I need to use a 3" color frame extender on all the S4 zooms. With them most any color lasts OK.

If I had a large inventory of fixed lens S4's I was re-locating a lot, the color frame extender would be a PITA.
Thus I would follow your well thought out logic and stick with 575. 

SB


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## lightbyfire (Jun 14, 2007)

We originally lamped our theatre with all 575 and now two years later we are starting to transition to 750. 

I have found that the dimmer limitations are usually unique and you can always lamp back down to 575 if you need to. the 750 while harder on gel and gobos makes a much nicer light in my opinion, particularly in amber drift. so for us it is less a practical decsision than visual.


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## zac850 (Jun 14, 2007)

For a 25-35 foot throw I'd say go with the 575s. The only real reason to go with a 750 is if you need the extra punch, and by the sounds of it, your not going to need that. The 575s are plenty bright for your throw.

The cooler lamp is also easier on the fixture its self, and the entire source4 should last longer with the lower wattage lamp.

If in doubt, you could always get a 575 and a 750, go in the first day, put two next to each other, and see if you really need/want the more powerful lamp.


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## Lightingguy32 (Jun 14, 2007)

Stay with 575, at those throw distances, 750s act like specials (centers, gobos etc.) Also the 575 is a more flexible lamp in terms of voltage ratings (anywhere from 100, 110, 115, 120). How ever if you do need a few 750s keep them in stock for specials only.


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## icewolf08 (Jun 14, 2007)

For your space and throw distance, you will probably be fine with the 575w lamps. The other thing that you should look into is what the actual output voltage at your raceways/drop boxes/etc. is. If you are running at 115v then buy 115v lamps, but if you are running at 120v you should get the 120v version of the lamps. It is a small difference, but using the correct lamps will give you the best output.

Also to consider on you lamp choice is that the long life and high output lamps have different color temperatures, listed below:
HPL 575/115/X	2000Hrs.	3050K	12360 Lumens
HPL 575/115	300Hrs.	3250K	16520 Lumens
HPL 750/115	300Hrs.	3250K	21900 Lumens
HPL 750/115/X	1000Hrs.	3050K	16400 Lumens​Given this, you will notice a difference in color between the long life and high output lamps, so if you need a whiter light you will want the high output lamps.

As for your question on what we use. I use all high output lamps in every fixture that there is an option. For my Source 4's I use 575s in all the 50˚, 36˚, 26˚, and 19˚ units. For my Zooms, 10˚, and 14˚ units I use 750s.


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## ship (Jun 14, 2007)

Math question for someone that more easily does the calculations than I do. This might play a bearing on what HPL lamp would be best for your situation. I also agree with the higher wattage lamps for the longer throw situations - law of squares compensation and also giving you some head room on stage for installing brighter lamps where more punch is needed or doing say patterns. Than of course, once you go long life or 120v as options in extending life (there is also long life 120v lamps but they are for the most part worthless,) you can still use the high output lamps for your practicles when you need to so the 575w for specials headroom question is a bit lessened by way going high output.

Here is the formula for what could in theory work.

Take as a given (as modified by actual voltage at full,) 118v at the fixture.

The actual formula changes slightly dependant upon what text you read but the following formula should get you into the range if used to answer how it modifies the below lamps.

For every 1% change in supply voltage over the rate the lamp is designed for (or inversely), light output will rise by 3.6%, color temperature will increase by 0.4% and lamp life will be reduced by 12%.

Now for the lamps to consider - 575w/120v & 750w/120v high output or 575w/115v & 750w/115v extended life lamps.

Sample lamps to figure on would be the following: (note brand to brand actual output can also change - this is a base average figure not associated to any one brand to do the math with. Many more recent upgraded lamps have higher outputs.)

HPL-575/115v+; 3,250̊K, 16,520 Lumens, 300 hours @ 115v.
HPL-750/115v+; 3,250̊K, 21,900 Lumens, 300 hours @ 115v.

HPL-575/115vX; 3,050̊K, 12,360 Lumens, 2,000 hours @ 115v.
HPL-750/120X+; 3,050̊K, 16,400 Lumens, 2,000 hours @ 115v.

HPL-575120v+; 3,250̊K, 16,520 Lumens, 300 hours @120v.
HPL-750/120v+; 3,250̊K, 21,900 Lumens, 300 hours @ 120v.

Following the formulas re-calculated for 118v and compared. You now have something in common to work with in seeing what’s the best lamp for your situation in balancing output with lamp life and it’s not always lamp life that is the best solution but often can be once used to it. Also, color temperature of the lamp will effect what you think is brighter. Often you can live with a little less output - one’s eyes adjust, when given a bit more color temperature in still thinking it’s bright. This as opposed to more luminous output but less color temperature - your eye more notes color temperature than overall output.


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## gafftaper (Jun 15, 2007)

Dang SHIP! I ask a simple question and you give me home work. School is supposed to be over for the summer!!




Thanks buddy.


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## Pie4Weebl (Jun 15, 2007)

I have a question in comparing 750 lamps, when looking between the HPL 750 300 hrs 21,900 lumens and the HPL 750x 1,500 hrs 16,400 lumens, would running the brighting light at 75% and getting the same output as the long lasting one give you a longer life comprable to the extended life one. The reason I ask, is because if it did, you would still get the benifits of being able to use hte fixtures brighter when you need to.


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## gafftaper (Jun 15, 2007)

SHIP does that equation work for dimming as well as supply voltage changes? 

Can we say dimming a lamp by 25% will result in a 25X12%=300% lamp life increase? 

That doesn't seem right. 


By the way a side note here... I do know how average lamp life is calculated. They take 100 lamps fire them all at once and whenever the 50th lamp burns out that is what the official life is declared to be. So 30 could burn out in 10 minutes and 2 could last 5000 hours... but if the 50th one burns out in 300 hours that is what they declare the average lamp life.


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## Chaos is Born (Jun 15, 2007)

gafftaper said:


> By the way a side note here... I do know how average lamp life is calculated. They take 100 lamps fire them all at once and whenever the 50th lamp burns out that is what the official life is declared to be. So 30 could burn out in 10 minutes and 2 could last 5000 hours... but if the 50th one burns out in 300 hours that is what they declare the average lamp life.



Is part of a bell curve equation... basically you will have a general amount that are going to fail early and some that will fail well after they are thought to. However what they do is they measure how long each lamp takes till they burn out and plug them into a graph and take and find where the top of the curve lays where the most burned out. They also might use the 10% or a 15% factor, where they take and they give a range for where the lamps might go out and take the better number, so really the average could be 5% to 7.5% lower than what they actually are saying it is, but a higher number is making them look better, and sell better. 

Understand also that lamp life is based on a constant on status. No super fast fade up or out, a constant on. When you take your lamp from 0-100% in a 0 count it really cuts the lamp life down drastically. Its even worse if you take it out fast and bring it right back up fast very quickly, these lamps were not made for strobing at all.


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## Charc (Jun 15, 2007)

And lamp life isn't life of lamp. It is life of lamp at rated wattage or intensity or temperature. I can't remember. But it has to do with a shift, not when it dies. I can't remember exactly which it is, but it was in _Designing With Light_ somewhere.

(I could be way wrong though.)


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## ship (Jun 17, 2007)

Yes as a general principle 75% is a percentage of applied voltage thus your lamps do extend their lives in exchange for color temperature and luminous output. You can strobe these lamps as long as they are warmed, just a question of filament size in stobing verses not strobing fast enough. Lamp life, while somewhat standardized is only somewhat done so. 

Take say 10% and throw them out of a sample that's say 100. After 10% burns out from there you have your expected lamp life. Or something like that often. Expected lamp life has gone thru some changes as with brands publishing wishful thinking at times and or in general at others testing different than others. For the most part any figure of lamp spec is only reletive and at best a base line to calculate from.

Will your HPL lamps work 300 hours at 115v? Don't know new to spent. It's a figure to work with however. One that should at least as base line become a figure to work with.


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## gafftaper (Jun 17, 2007)

gafftaper said:


> By the way a side note here... I do know how average lamp life is calculated. They take 100 lamps fire them all at once and whenever the 50th lamp burns out that is what the official life is declared to be. So 30 could burn out in 10 minutes and 2 could last 5000 hours... but if the 50th one burns out in 300 hours that is what they declare the average lamp life.



I should clarify this statement. I don't know this from personal experience. I found that info in the book "Automated Lighting".


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## ship (Jun 20, 2007)

Pie4Weebl said:


> I have a question in comparing 750 lamps, when looking between the HPL 750 300 hrs 21,900 lumens and the HPL 750x 1,500 hrs 16,400 lumens, would running the brighting light at 75% and getting the same output as the long lasting one give you a longer life comprable to the extended life one. The reason I ask, is because if it did, you would still get the benifits of being able to use hte fixtures brighter when you need to.



Ah' the math kicks in, (or the science of lighting by design) but have you done the full math as far as it's not just luminous output verses lamp life that at some point crosses (given a specific voltage) but also color temperature that while minor and often we cannot notice a 300K difference is noticable after that. Does this question fall within the 300K difference by doing the math? Or in having head room, can your audience on the easy side and more important you deal with and get used to amber shift at 75% by way of retaining that head room? Or more likely are you going to get used to stepping it up a few notches? Is not after you get used to 75% of a lower output and color temperature lamp also headroom in going full for scenes once you get used to the color temperature and overall intensity of less light? This a sort of - how did people ever survive with radial Lekos question - this given magic on stage was made in earlier eras but with less output and color temperature.

Yes, being able to send your amp to 11' is always a good concept in having head room, but it's the overall design of the scene that is the main thing, after that flexibility is also to design in. Choice between long life, extended life and 120v lamps is a big question when budget is not there to just have at the most powerful. Don't think anyone in the industry has done a comarison that's thorough enough on what lamp would really be the most cost effective.

Time for some math major with summer break to plot out a graph of based upon the math what each of the four basic lamp types will do - including the useless 120v long life lamp. In than looking at the math show what is the most cost effective lamp based upon some norm for design. No, your Lekos at some point might not be the blue/white one is used to, but they will be efficient in balancing output and color temperature verses lamp life. This balance in what does give the best is important and perhaps, who knows if you submit it to ETC, they might publish your findings in what one should recommend to a theater on a budget.


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## skienblack (Apr 5, 2011)

Why do people not use HPL750s in all their units and thus not have to use them at the higher intensities when they don't need to? In our space we unfortunately use 575s and even then we rarely will use a single instrument at full.


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## shiben (Apr 5, 2011)

skienblack said:


> Why do people not use HPL750s in all their units and thus not have to use them at the higher intensities when they don't need to? In our space we unfortunately use 575s and even then we rarely will use a single instrument at full.


 
Because if you have to tie 4 units into the same dimmer you cant without risking some idiot turning them on, or only using them at a low intensity. Also, its generall cooler (cant imagine by much), gel burning out, etc. If you dont often use instruments at full, it really doesnt matter what the wattage is. One of the first posts i made on this forum was in relation to an arena I was working in where the installed lighting was a bunch of 575W S4s. We actually ended up adding twice as many PAR EAs and As many S4s were speced, in addition to lamping all up to 750W to get the intensity. However, in a black box, you generally dont need this and often you need to gang as many instruments as possible to avoid running out of dimmers.


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## derekleffew (Apr 5, 2011)

skienblack said:


> Why do people not use HPL750s in all their units and thus not have to use them at the higher intensities when they don't need to? ...


Another reason, even if the 575W is at full and the 750W at 50%? 76.6%? (I could do the math, but I won't) is putting out the same number of lumens, the higher wattage lamp when dimmed will have a significantly lower color temperature, due to amber-drift.


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## Grog12 (Apr 5, 2011)

Also not all S4's are created equal. Depending on your venue they may have a batch from the pre-750w days. In my venue its a matter of ease as we have a mixture of Jr's, PAR's, PARnels and full size S4. I stock one lamp for them all as opposed to several different kind of lamps.


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## bishopthomas (Apr 5, 2011)

My 750 watt lamps have an extra post (for stability?) that are not on the 575's. My S4 lamp housings have a socket for this piece but the pair I just rented did not. I ended up lamping one at 575 and had a spare lamp housing that I put on the other fixture. Is this common?


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## jglodeklights (Apr 5, 2011)

My understanding is the post is there to prevent the installation of 750watt lamps in caps that are not rated to that capacity, such as the junior units.


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## DuckJordan (Apr 5, 2011)

jglodeklights said:


> My understanding is the post is there to prevent the installation of 750watt lamps in caps that are not rated to that capacity, such as the junior units.


 
Thats exactly the reason, The 575 watt caps without the extra prong hole cannot handle the extra wattage so to make sure there wasn't issue with users putting a 750 watt lamp in a 575 unit they added that prong. Also you can put 575s in 750s no problem. Just the other way around is the issue.


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## LXPlot (Apr 5, 2011)

We use mostly HPL750 because we never have multiples on one dimmer and our FOH positions are about 50 feet from the area they need to hit. We do burn through gel's quickly, but we also have a stock of gel shields for scrollers and other long lasting units, and we have a bunch of 575s in storage. Just thought another example might help.


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## jglodeklights (Apr 5, 2011)

One thing to keep in mind when it comes to burning through gel is that by properly benching units and properly adjusting beam focus gel life and lamp life will be enhanced (more light passing out the front of the unit rather bouncing around in it and being converted to heat there). Additionally, one can also use a pounce wheel to create "vent" holes in the gel that will allow additional heat to pass through them. A little time consuming, which is why I assume most people don't use the technique (have others had the luck with it I have had?), but in long term installations where a gel extender isn't available or is impractical it can help.


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## avkid (Apr 5, 2011)

575 in all the S4 and S4 PARs.
Flexibility is important as we seldom do the same thing twice.


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## mstaylor (Apr 5, 2011)

jglodeklights said:


> One thing to keep in mind when it comes to burning through gel is that by properly benching units and properly adjusting beam focus gel life and lamp life will be enhanced (more light passing out the front of the unit rather bouncing around in it and being converted to heat there). Additionally, one can also use a pounce wheel to create "vent" holes in the gel that will allow additional heat to pass through them. A little time consuming, which is why I assume most people don't use the technique (have others had the luck with it I have had?), but in long term installations where a gel extender isn't available or is impractical it can help.



I was taught to vent gel in my Roscolene days in the 70s. Guys coming out of school these days look at me like I am crazy when I do it. I always vent with a pattern cutter.


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## jglodeklights (Apr 5, 2011)

mstaylor said:


> I was taught to vent gel in my Roscolene days in the 70s. Guys coming out of school these days look at me like I am crazy when I do it. I always vent with a pattern cutter.


 
Probably less effective now as the Source 4 transmits much less IR and converts much less of it to heat at the lens. I'm only 24, but I was taught to do it when working with the 360Q's Temple U. kept for student produced shows when we did a series of 4 shows in Rep. With a budget of $0 for lighting, we needed to make the limited supply of cool colored 7.5inch cuts last (not easy when undergrad directors keep yelling brighter). 

That is another reason for using 575's... brightness is relative (though there is a certain point at which our eyes receive too little light to allow our brain to perceive what we are looking at clearly). If you base everything off of 575watts, if you really need a unit or units to be brighter than the rest, you can lamp them up to 750 watts. Or you can switch from a long life lamp to a standard life. As long as you remember to switch them back when done......... ( I once got a rental package of S4's with everything except a 375 HPL in it, say what?)


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## MPowers (Apr 5, 2011)

Chaos is Born said:


> ....... i'm noticing that a good portion of the deep saturated colors don't come in a high temp version... and end up burning through the gel about half way through the show.......



Just thinking about when I broke into the biz. Gel was GEL. Colors like Special Lavender (similar to the current Rosco R54) had to be replaced nightly in a musical. Pre-show check was not only to check for burnt out lamps, focus position (did a lamp get bumped by moving scenery or crew. Especially important with shin busters or side lights low enough to be hit by side stage scenery) but also what color needed replacing that night. The lavenders faded very fast, the blue dye burning out leaving a pink color if not replaced. Light tech rooms did not have a file of used gel. There was no such thing then. Used = faded.


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## jglodeklights (Apr 6, 2011)

OOH OOH, How many newbies did you get to wash the gel?!?!?!?!?!?


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## Syphilis (Apr 7, 2011)

For a 25-35 ft. throw, 575W HPLs are definitely the way to go. 750Ws are best in larger spaces, in terms of lumen output.


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