Dimming 5K Fresnels ?

[JSFox]

We keep doing productions where I really want a 5k or two for a good strong sunlight. Is there a way to dim these or do I need to stack up a bunch of 2k's?

[SteveB]

What kind of dimming and circuit system do you have ?.

You will need a 6kw dimmer - which is what's typical, as well as #6/3 SO cable with rated connectors. The 60 amp 2P&G is typical as what you get from shops.

SB

[SHARYNF]

Some of these are turning up on ebay, since they were more common with Film production, so you might be able to get one cheap

Just remember most of the 5k is turned into heat, so these are like the sun in more ways that one ;-)))

Sharyn

[personalZEN]

5K's are fantastic. I use them all the time... (with a large format scroller, they become a whole new lighting tool) A few things to remember:

-A DPY 5K lamp can be expensive ($250.00 ish) so be sure to ALWAYS warm the lamp a few minutes before rushing a full 120v onto them. NEVER move them when on. Let them cool 10 minutes, then move. A 5K filament is HUGE, so it's quite fragile when energized.

-If your fixture doesn't have a metal wire grid over the fresnel lens (I'm assuming your using a fresnel) consider purchasing a shatter-proofer wire grid thingy (can't remember what you call those things, NOT a scrim.. but the more open one that protects the user from blow-shatter) 5K lamps can produce some crazy shatter if mishandled, or voltage rushed in strange circumstances.

-Strand makes CD80 DMX controlled 6K Solo paks that are perfect for this exact application.

-If you have a modular dimmer rack system, you may be able to simply swap out a dimmer module and presto.

[SHARYNF]

If you are interested there is a guy selling some colortran dimmer packs pretty inexpensively that will do this (around 400 bucks) carlosanddiane at hotmail dot com is carlos email address. You can mention my name, I was looking at one of his 12x2.4 units and I know he has a number of 6 by 100 amp bates

Sharyn

[Footer]

Along with the prewarm thing, when you are programming the show the cue before you bring up the fresnel, prewarm it to 5 or 10 percent. This will not actually throw any light out the front, but it will make the fixture actually have some type of response time. Also remember that if you want a fast blackout, you aren't going to get it.

[SteveB]

Originally Posted by SHARYNF

If you are interested there is a guy selling some colortran dimmer packs pretty inexpensively that will do this (around 400 bucks) carlosanddiane at hotmail dot com is carlos email address. You can mention my name, I was looking at one of his 12x2.4 units and I know he has a number of 6 by 100 amp bates
Sharyn

Hopefully the packs will contain some 6.0kw dimmers, as you cannot hookup up a 5kw fresnel to a 2.4kw dimmer !.

Well, you can but it's a very brief effect.

FWIW, Colortran D192 dimmers @ 6.0kw are hard to come by, but one known supplier who might have some is Litetrol Service - 800 548 3876

SB

[JSFox]

All, thanks for the great info. I'm already a bit over budget this year (mackie crapped out so had to buy a new sound board) so this is on top of that. I'm hoping to get a go ahead tomorrow and will start following some leads. Any more comments on using them (or how useful they are) still appreciated.

[personalZEN]

Once again, 5K's are great, but they are a workhorse. I would never hang them in a space with a grid less than 20ft or with a proscenium width less than 30ft. It's just flat-out overkill.

I mostly use 5K's arri's for front color washes w/wybron 5k format scrollers in Studio Black Boxes in a McCandless system where I really need some color. Or I'll use them as cross back light with L201 for a nice sharp separation from background and some hair-hi-lights. They make great Sun sources or Moon washes.

this show: http://www.kmvisions.com/work/idos-ground/

Had 2 5K arri's w/barndoors and Wybron Scrollers in the grid all the way stage left at 20ft to provide a nicely saturated Stage Left high-side. (unfortunately you can't see the actual units in any of the shots)

this shot: http://americanoperatheater.org/slides/about_7.jpg

Had 5 5K arris' w/ a peachy colored gel (can't remember what color, but it was def a Lee Hi-temp) about 3ft off the floor on rolling studio stands (they were re-gelled and re-positioned during intermission) all lined up like dance side-lighting at stage left. In this shot, the 5K are just about 30 ft away from the performers and are at about 75% intensity. You can see how the 5K's really punch light. All the other sources in this photo are StrandSL 575's

Hope that helps.

I use colortan 2k's, strand 3k's, arri 4k HMI's, and arri 5K's in almost all of my lighting plots, and even in smaller spaces, because I like the bang you can get with higher-wattages. Just remember, they are very very expensive to run, replace, repair, and relamp.

-Kel

[ship]

Originally Posted by JSFox

All, thanks for the great info. I'm already a bit over budget this year (mackie crapped out so had to buy a new sound board) so this is on top of that. I'm hoping to get a go ahead tomorrow and will start following some leads. Any more comments on using them (or how useful they are) still appreciated.

In use of them, open up and inspect the tension and gapping of all plugs on or all cable feeding them. For some reason if using the more or less standard 60A stage pin plug to feed such a fixture, they constantly are getting loose set screws at the plug. Once a year all such plugs need re-torquing even if in theory against code to do, it's necessary. Due to the load, the conductors feeding the plugs expand some under the set screws and re-settle after expansion thus you now have loose plugs. This especially if using "Union" brand plugs, but common to all. Check the tension on all wire to screw terminals - they loose you now will most likely will have a melt down at the plug. (I have lots of examples of this condition on my wall of shame - the plugs will even melt together.) Not just a question of if you didn't wire the cable, it's not to your specs, even if you wired the cable it might after heating up not be to your specs. Where possible, open up all cables and plugs and test the torque of the set screws. Normal electrical practice does not allow or recommend that you re-tighten stuff such as circuit breakers... don't care, in this case it's I believe 20 inch pounds of torque that's required, verify it if you have time and or at least do a sampling of what you have or get before using it. If what you test complies, fine, if what you have does not, be cautious - might not be you that wired the stuff, but it is you responsible for making it work in the end.

No matter if rented (be cautious) repaired, or new, if in your system, do at least a spot check of a few cables and plugs (remember that the 60A is reverse neutral/ground from the 20A version), any even if you built it could have torque problems due to the amperage. I did such a policy of once a year checking all the plugs, it worked well in reducing repairs by about 90%.

After this on a 5Kw fixture, extract the lamp. If Strand Bambino fixture, that's easy, if Mole Richardson, caustious of the base often broken porcelain but still fairly easy to remove unless welded to the contacts. If most others, be very careful in extracting the lamp from it's base. Often a lamp will be hard to remove, than come loose all at once in the upper pinch hitting the top of the fixture. Hit the top of the fixture in extracting the lamp and you now have very expensive trash in your hands. Still very necessary espeically in rental equipment if not your own to verify that the lamp, it's base and it's wireing is in good condition. Cement holding quartz glass to porcelain in good condition or all cracked and leaking silica sand? Fine to some extent as long as gravity mounted but if it's loose in the porcelain part of the lamp attached to the pins, much less if hung in other than vertical base down with silica sand leaking, replace the lamp. Such lamps often have issues with heat - at times they will have a hose ring attached around the body of the lamp to help keep it together - that's fine as long as the lamp is in good shape.

First examine the lamp. In good shape? Fialment still hanging off it's filament hangers, no white finger print spots to it etc? Look at the pins... some oily coating is fine as long as there was no pitting and or welding to the lamp base. Welding of the lamp to it's base is a bad thing and induced filament failure lamp failing during a show heat to the - you need this lamp to work theory. Look at the filament again, bunch of sparkley cracks, thinning out of the filament towards the center or anything unusual? Clean the lamp just to be sure if fine. If it's pins were fine also, it says good things about the lamp base.

Now with lamp removed, pull out an inspection mirror and flash light. Have a look at the lamp base contacts with it and verify that it's not all pitted, oxidized and or welded in being shot. Your lamp upon removal should have had either something that releases the tension either a lever or wing screw, or tension itself by way of rocking you are able to get the lamp out. IF that lamp came out too easily, you have shot retention springs on the lamp base and will no doubt have also seen some welding going on given the current.

Look at the porcelain of the lamp base - this especially if Mole Richardson in brand, verify that it's not cracked. OF cracking, also verify that your lens has a safety screen on it - not safe to use without one. Reflector clean and the adjustment focus knob works plus stays in place. Make sure that the reflector is also tight.

Following this, get that inspection mirror and flash light in behind the reflector. Have a look at the condition of the wiring especially as it leaves the lamp base. If one say sees insulation flaking off the conductors, it could short itself should it be put into spot position - don't use such a fixture that has insulation flaking off. If you can on a few, flex that heat wire inside the fixture that runs between lamp base and switch or strain relief and see if it cracks. Also a sign of a bad fixture. If accessable, the fitting that converts heat wire to the fixture cable is also suspect in having loose terminals.

Lots to check in a 5Kw and anything over 1Kw Fresnel. Spot checking at very least is a good thing. Heat is your enemy due to expansion and contraction and materials just getting hot enough to break or become brittle.