I have sent a PM to AZ Video because I know someone would tell me to ask him but I thought I should post here also in case someone else also knows if these two ballast can be used together to overclock the LLABS T15 400watt Lamp to 575 watts.
I am now useing this ballast http://www.1000bulbs.com/400-Watt-Metal-Ha...-Ballast/32380/ with the the LLABS Lamp and would like to know if I could just add this ballast http://www.1000bulbs.com/175-Watt-Metal-Ha...-Ballast/32378/ to overclock the LLABS lamp to 575watts ?

I had the same idea. I took the igniter off the 175 and it worked for about 10 seconds....then there was a funny electrical sound and the 400w eballast died.

Yours being both magnetic ballasts you might be ok, but from the few seconds i had it working, i don't think i could have dealt with the color temp change

I'm surprised it worked for ten seconds. The output of an Eballast is at a vary high frequency perhaps 40Khz or so. If the second ballast is not in phase with the first they will "fight" each other and the Eballast will fail.

Coil ballast are in phase from the line input voltage and if the polarity is correct then the power will add. I did say in the pinned post that the two ballast idea is only for coil ballast.

If you love Eballast then a 600 watt Eballast might work for a 575 but they cost alot.

I got the idea from one of your posts year ago. Didn't put much thought into the compatibility of the ballasts, just decided to get dangerous since I had the 175watt around anyway (working on a very small projector).

Arizona, I don't much visit lumenlab anymore since I've moved on to other projects so I just wanted to say that your work, and elkins, dazzla's, etc has all taught me a great deal and I wanted to say thanks!