Improving Dynamic Lamp Dimming - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 2 Old 11-04-2019, 04:55 PM - Thread Starter
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Improving Dynamic Lamp Dimming

I have a theory on the lamp dimming systems(bulb or solid state). On a W1070, the Smart Eco setting causes very obvious pumping or rough changes in lamp level which looks more like physically changing a brightness/contrast setting step by step. The lamp dimming causes the current draw to change and a varied current draw will cause a noise generating voltage to develop across the inductance of the power cable, this noise passes through and affects the performance of voltage regulators. A quadrapole(star quad) power cable has a much lower inductance than straight standard cables, lowering the inductance will lower the noise. With the W1070, the very noticeable stepped pumping of the lamp dimming was almost completely resolved. Only in some brighter scenes was a very smooth change in brightness noticeable but 0 stepped pumping and absent from darker scenes or even dark to bright scenes, for instance during a smokey daytime scene in the battle at the end of the magnificent seven, the lamp level transition could be observed due to the smooth darker smoke that would flow over a brightly lit scene or a smokey scene that would light up with sunlight. These scenes without the star quad power cable though are a chunky mess and I would normally switch back to normal/eco lamp mode.

Ive tried this type of cable on a JVC RS45 as well and didn't notice any changes with video performance over a standard 14/3 cable, the power draw of that projector is very stable. I haven't performed double blind testing, but I've gone back and forth several times with the cables to the W1070 and the difference is very apparent. I'm curious to know if anyone using a dynamic lamp dimming system has tried this type of cable out. I know there's that adage of all the wiring before it what difference could the cable between the outlet and the unit make, but due to the geometry of the cable and the low inductance even a couple of feet is enough to reduce the noise. The cables can be constructed for cheap you only need some 16/4 wire, a ground conductor, and some plugs. Im only aware of one company that sells prebuilt cables, VH Audio's Flavor 4.

Please note, I'm not selling anything, Im not an electrical enigneer, and I'm only sharing observations and am curious if the theory has any merit and if anyone else has tried something similar. If it sounds like bs feel free to sound off you won't get any arguement from me =/

Last edited by bdht; 11-19-2019 at 11:04 PM.
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post #2 of 2 Old 11-09-2019, 11:43 AM
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I would suggest reposting this to the under $3000 projector forum, as that is where most of the Dynamic lamp dimming users are.
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