Looks like the lows are sharply cut off at 200~ and below. In the second plot, the lows appear to cut off sharply at 400~. It would have less space-shuttle/EAS sound if the lows extended down flat to around 100~ and then gradually rolled off. Here is the built-in frequency response of the pre-amp I use with my unamplified D-104 (scroll down mid-page on the attachment). The acoustical bump in the D-104 response adds to the presence rise built into the pre-amp. The low end is flat to below 40~, but the microphone frequency response rolls off at the extreme low-end. The low-frequency roll-off of the D-104 is less than that shown in the curve, when the mic works into a high impedance load on the order of 10 megohms or more. Mine works into 20 megohms; low-frequency rumble from distant aircraft registers on my monitor scope before I can actually hear it with my ears, but I have never had a signal report that I was 'bassy'.