I thought that was where the article was heading when it mentioned that horizontal was better (and the unstated fact that mono was horizontal), but it still too

I thought that was where the article was heading when it mentioned that horizontal was better (and the unstated fact that mono was horizontal), but it still took me a minute to realize that the 45 degree pickups are equivalent to midside. In (digital) mid-side you encode M=L+R and S=L-R. With this, if you breakdown the horizontal and vertical components: HL = +L/sqrt(2) VL = +L/sqrt(2) L = sqrt(HL^2 + VL^2) HR = +R/sqrt(2) VR = -R/sqrt(2) R = sqrt(HR^2 + VR^2) H = HL + HR V = VL + VR = (L+R)/sqrt(2) V = (L-R)/sqrt(2) Note that VR is negative and HR is positive because the sign of the pickup is inverted in the diagrams.