Technique: Blowing C Natural

On the recommendation of a Chiff and Fipple forum post I bought a Korg CA-30 tuner. It immediately helped me fix a problem I've had getting C natural to sound right. I've tried alternate fingerings, but they didn't help at all. With the tuner as feedback, it was very simple to figure out the correct breath pressure.

I suppose I should be able to do this entirely by ear, but it hadn't occurred to me that the correct pressure for C natural would be lower than for B (on my whistle, anyway), or that the variation in pitch for C natural would be so much greater than for other notes. That alone was worth the $20 I spent.