For those who bought the Bumblebee VFE main board from me, I want to clarify things up. Finally, I got everything tweaked up nicely and got the help from Peter.
(https://image.ibb.co/hDZ0AT/bumblebee.jpg) (https://imgbb.com/)
A 1nf capacitor should be placed between pins 6 & 7 of the 4558 op-amp to reduce distortion bleed-through from the envelope trigger circuit. Also, do not install the JFET trimmer. Instead, install a jumper between the left-middle pin of that trimmer and its bottom pin.
For my first build, I did 1nF cap placed between 6 and 7 of the 4558. The second build, I didn't do it. Comparing those two builds, I like the one without the 1nF. I feel my swell a bit grittier and yes, it's distorted when the trigger is all up. However, I like it.
NOTE: I've seen Peter did connect the trimmer with a resistor. Below is the value and explanation of how you should wire the JFET control. Use your ear to set the trimmer based on your liking for the swell.
(https://preview.ibb.co/goYcqT/unnamed.jpg) (https://ibb.co/fnpvc8)
Hopefully, this post is helpful as I am hoping to see the MBP Bumblebee rolls out soon.