As we are preparing with our group (Panta Rhei) to our 50th anniversary concert in April, I got some first hand experience with my FI V4. I am using Rotosound strings with rather metallic sound (like Greg Lake), it has a nice bass sound in the lowest octave of the bass, but if I play higher then the bass range is thin. To solve that, I created a nice sub-octave bass sound with the FI V4, that fills the missing low range. I mix it about 50-50% with the original bass sound. When I started to use this, my first remark was that it was fine when I play loud, but when I picked softly it remained much louder than the bass. With some experimenting I figured out that if I use Accent as the source for a Flexi controller, and direct it to the VCF LOG volume of the main mixer, and additionally I select the first upwards bending curve then I get a very good matching of the synth volume with the bass volume. After that, I found that the only remaining problem is that if I play in the deeper range of the bass, then the sub-bass kills the loudspeakers without any useful purpose. So, I took a second Flexi with Pitch as the source, and feed it to the VCF LIN of the main mixer through an S-curve. Then the sub-bass nicely fades out in the deep range, and fills in only when I play high. Please note that I renamed the file extension to *.txt, otherwise TalkBass does not accept it. You have to rename it to *.pr4.
Andras Szalay