Part 3 - Fixing the Tweeter
First off, I'm going to have to write part of this and finish it at home as I don't have all my info here at work on my lunch break.
So, when I first tested my OB system there was a big problem with rising tweeter response. I attributed it to the fact that I didn't have a 3 ohm resistor in the tweeter's network (R3a in the diagram) to cut it down. When the resistor finally came in I installed it and the tweeter rise became a drop-off. What happened? I'm not sure but I have two guesses.
Theory 1: The tweeter still has rising response and it is making the tweeter clip in the freqency sweep causing it to be measured as decaying response. As I have mentioned before my measurement gear leaves a lot to be desired.
Theory 2: I should have padded the tweeter with an L-pad instead of just one resistor. When I first started I didn't understand the beauty of L-pads. I'm ordering new resistors and adding the R3b segment to try to see if that fixes anything.
When I get home I'll add the values for the componants in the diagram below. One thing I'll point out is that the box labeled "L-pad" is a
variable stereo L-pad. I used this so I could adjust how much I cut the upper frequencies.