Thanks...I think it was just the transition point making it appear that way ...I don't perceive it going darker when it changes to 5dB gain reduction but that's just me. I have measured that the frequency response does not change when compressing. Maybe somebody else can comment if it sounds darker to them too.
Here are some distortion measurements with 7dB of gain reduction. In the top picture release was set at slowest. In the middle picture release was at the fastest position. In the bottom one release was at slowest position.
Steady wave distortion measurements with gain reduction aren't really useful. If I want to make them look good I just have to use slow release and higher the frequency the better.
0dBFS = +20dBu
FT dispalys noise voltage density. It's the energy by bin. In order to determine the global figure, you need to multiply the density by the square root of the number of bins.What! So 0dbU is -20dBFS which means the noise floor of your tube device is -110dBu? I didn't think tubes were that good. Nice!