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A color changing device for conventional theatre fixtures. Invented in the early 1980's by Keny Whitright (then working for Great American Market, now president of Wybron), with the "Colormax," and later "ColorWiz," products. Uses a gelstring, consisting of 10-32 frames, that rolls in front of the beam to change colors, controllable via DMX. Major manufacturers include Apollo, ChromaQ, and Wybron. Some, such as the Morpheus Colorfader, Wybron CXI, and Apollo MXR use two or more strings to allow for subtractive color mixing to achieve 100 or more discrete colors, see below.

Color scrollers (with the exception of rare "stand-alone" units such as Wybron's discontinued The Scroller), are powered by a separate power supply (PSU) normally providing 24V DC to the scrollers via 4-pin color changer cable. DMX data is delivered from the lighting console to the PSU via 5-pin DMX cable, then travels along the "daisy-chained power/data circuit" to each scroller. The color scroller PSU is often positioned in the center of the pipe, allowing a group of scrollers to provide color changing capabilities to lighting instruments (ellipsoidals, PARs, etc) on the stage left as well as the stage right side of the PSU. Many manufacturers highly recommend using a 4-pin cable to "loop-back" the last scroller back to the PSU, so as to boost the line voltage available for all units on the circuit. As a secondary benefit, the returning 4-pin cable will terminate the DMX data when plugged back into the PSU.

Copied directly from this post by [user]Icewolf08[/user]:
Differences in systems and PSUs:
Most, if not all scrollers require a PSU (power supply). The PSU takes a DMX input and sends it out along with power over 4-pin XLR to the scrollers. There are two common types of scrollers, the "Chroma-Q" style and the ColoRam style. The biggest difference is that they use different pinouts for power and data. Apollo SmartColors, Chroma-Qs, Wybron ForeRunners, and a bunch of powered accessories use the "Chroma-Q" style PSU. Wybron ColoRam, and CXI use the ColoRam supply. These two different styles are not compatible with each other!

The "Chroma-Q" style PSUs and devices require (or strongly suggest) that you make a loop with the cable. Meaning that you go out from the PSU, daisy-chain to each device, and then run a return cable back to the PSU. This helps keep the voltage up on the line and provides data termination. This is why there are both 4-pin in and out ports on the PSUs. This style PSU also sends raw DMX data to the devices. Each device gets a unique DMX address which is set on each device.

The ColoRam style PSUs do not require to to make a loop. Also, the PSU does not send out raw DMX data. The data stream is translated to a proprietary stream. Each device attached to the PSU gets an address unique to the PSU that it is connected to and the PSU gets a DMX starting address.

Basic Scroller Types:
There are two basic types of scrollers, single string and multi-string. Single string scrollers give you a fixed set of colors, while multi-string scrollers allow you to mix colors. Due to the fact that single string scrollers have fewer moving parts and require less control they are significantly less expensive than multi string scrollers. You also get better transmission from single string scrollers since the light does not have to pass through multiple filters.

Dual string scrollers, while slightly bigger offer you more color flexibility. You will need more control channels for them, but they may eliminate the need to buy or make new strings for each show as you can mix a large number of colors.

As for the OP's situation, I would recommend the Apollo SmartColor Scrollers. IMO they give you the best for the money. I would suggest that you get the SmartColor 7.5 with the universal mounting plate, which you should be able to get for around $350 each plus $45 for custom strings. These units are light, simple to set up, and quiet. They also come with Apollo GelShield to protect the string. The universal mounting plate will allow you to use the scrollers on any fixture that takes a 10" color frame (like a PAR64) or smaller.

You also have to think about where you are going to using the scrollers, not only now, but in the future. You have many options for PSUs in varying wattages. The SmartPower 150 will power up to 5 SmartColor 7.5s. As a user of these scrollers and PSUs, I have a bunch of SP150s so that I can put scrollers anywhere, and if I need more power I just use more PSUs. You have to think that in the future you may not use the scrollers in the same place you are planning to use them now.

One of the other things that you have to keep in mind is that there is a limit to the amount of cable that you can use (or the amount of head feet). This is due to the resistance of the cable. Generally the maximum head feet per 150W PSU is about 200'. This means that even if you only had one device attached to the PSU, you may not get enough power to it if your cable run is over 200'. This of course includes the return run. I don't remember the price of the SP150, but I think that it is around $250-ish.

Multi-String Units:
Includes units such as the Wybron CXI and Apollo MXR. Both use individual frames of cyan, magenta, and yellow (two per on each of the two strings) to subtractively mix the desired color. While a live color fade is possible, it will appear "steppy," due to the individual frames.
Morpheus ColorFader, three individual strings of graduated saturations of CMY.colorfader.jpg In theory, these provide 256^3= ~16 million different colors. Syncrolite OnmiColor, using DichroFilm colors.

Pricy alternatives to conventional fixtures with any of the above scrollers are the: Ocean Optics Seachanger, Wybron Nexera, and HES/Barco ColorMerge, all of which are complete, non-moving, fixtures using variable glass dichroic flags. From the olde phart department: Here is an absolute truth that many of us have learned over a lot of years: Any moron can make one scroller that works. Now show me 100 scrollers that all go to exactly the same place, with the same DMX value, with old and new gelstrings, over a long period of time. That's harder--much harder! Sometimes the cheapest is not always the cheapest!
Ever wonder why the ETC Revolution got a retrofit Wybron scroller more than two years after its introduction? Hmmmm...

Lots more useful information in this thread:
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