Here's the link to the DD factsheet: http://www.etcconnect.com/docs/docs_downloads/datashts/DimmerDoubler_vF.pdf
Here's the link to the manual: http://www.etcconnect.com/docs/docs_downloads/manuals/DimmerDoubler_User_Manual_revA.pdf
The S4 Jr is a compatable fixture type, so you need X amount of HPL550/77 lamps, and X amount of dimmer doublers.
The rest assumes you have an ETC console as well as Sensor dimmers.
Essentially what you are doing is putting a 77 volt lamp into a fixture, with one 77v fixtures on ea half of the DD 2-fer (so they work in pairs, though you don't have to load both sides of a DD), you then assign specific Sensor dimmers to run in DD mode, which has one half of the dimmers sinewave output split by the DD, the upper half to one fixture, the lower half to the 2nd fixture. You then tell the console that you are running in DD mode. It splits a universe of DMX addresses into 1-256 as DD 1-256A, with DMX addresses 257-512 as 1-256B.
77v lamps run about $17, the DD is currently available as used from 4Wall/UsedLighting.com @ $89 ea., they say they have 35 available, and as they come from a reputable source, it's a steal. It's a good idea to maybe buy extra lamp caps for ea. fixture you want to DD, so the caps used for DD will have a twistlok plug as used by the DD 2-fer. Keeping the DD 2-fers at twistlok helps prevent damage and blown lamps. Or buy adapters.
Steve B.
[edited by: Steve Bailey at 8:30 PM (GMT -6) on Thu, Mar 26 2009]
1)Multiplexers are generally supplied with twist-lock connectors and therefore the S4 Jr with the 77V lamp would also need to be twist-lock. This is to prevent plugging an 115V source into a unit that has a 77V lamp.
2)Point in fact…you do not need an ETC console to dimmer double. (You do need Sensor dimmers and the Multiplexers) As Steve pointed out “It splits a universe of DMX addresses into 1-256 as DD 1-256A, with DMX addresses 257-512 as 1-256B.” The A and B convention is built into ETCboards to be helpful in keeping things straight but you could use any DMX board and just remember that dimmer 1 is now on DMX 1 and 257.
