I finished my first TubeTrap-like 16"x4' bass trap last weekend and have been testing it during this week. I started off with a listening test and I needed only 5 minutes to hear a remarkable improvement in sound. So I moved on to the scientific testing phase , started with my self-burnt CD with tones every other Hz and measured the freq response with a RS SPL meter from 20 to 200 Hz. BTW, I modified my RS meter so that it reads flat in the bass frequencies. I used Excel to plot it and there it was, a graph showing significant improvement around some of the room modes. So far, so good. Then I started measuring with ETF5, and strangely no difference came up at all. So I took the trap out of the room, measured the room again, then brought it back in, another measurement and... nothing! So now I'm thinking the trap "broke" or I didn't take valid measurements before, so I repeated the procedure with the CD and the RS meter, and I got exactly the same curve as before, clearly showing the differences. Could someone please help me understand why ETF is not showing what's going on, even being it so clear that I can hear it? Thanks!