I've only tested one of the two I have so far, although it appears both are from batch one. From what I'm looking at there is only a slight difference in the lower octaves. The old cal file seems to bring the response down a bit.First batch UMIKs end at the serial #188 and second batch UMIKs are serial #190-539... there is no serial #189 :huh: appears third batch is serial #540-???
I suspect the biggest difference you'll find between files in the first batch is below 20Hz response. With the second batch it is any thing below 990Hz and basically gets worse the lower you measure.