Using resistors and creating waste heat just seems sloppy to me. If it were a real small lamp it'd be different.
Not only did that sound kinda snobby, it's not really what I meant. :stoned: What I was thinking was: only if the difference in voltage requirements of the reds vs. the blues is small, does shaving a volt or two with resistors make sense. :thumbsup: Indeed, in that circumstance, dropping the blues a bit with a resistor may be the wisest solution--especially if bringing in a separate power supply is problematic.

I just got used to planning for a worst-case scenario based on the data sheets for the LEDs. Depending on what bin the dealer decides to send you, it looked like it was very possible to wind up with blue LEDs wanting a full 4 volts more than the reds. I guess I resigned myself to thinking that was what I was gonna wind up with.

But Weezard, I guess you've been tellling me your blue and red 15 watters are not that far apart in their voltage requirements. That opens up new possibilities (like judicious use of resistors). Sorry, I'm dense sometimes! :i feel stupid: