This post is a definitive testing of my circuit, meaning it's better documented than the first one.
It's therefore an ask for help to all of you who might know anything about circuits and guitar pedals.
I'm very lost and lacking of time right now, so I would thank ANY help!
Soo I was able to test every point that I wanted today.
Remembering, this is the schematic on LTSpice (for easier visualization):
part 1 -
part 2 -
And this is the official schematic (with real values) on EasyEda:
Now, as I referred in that previous post, I was getting a very strange frequency response after some time not using/testing the Phaser Pedal (before this time everything was ok). My conclusion is that there is a high pass filter throughout the circuit (that will be proven by images show below), that I cannot understand where comes from.
Before that, let me show the frequency response I once had with my pedal:
1 -
2 - With the trimmer in different pos:
As I referred, after some time without using the pedal, the freq response got kinda crazy:
1 -
2 -
That being said, note that "Good"="flat" and "Bad" = High Pass filter non sense (you will see below).
Output of the 2nd op amp (first of the phase shifting) is ok (zoomed in)
However the inverting and non-inverting inputs of the same op amp have this same response (bad):
In my head this isn't even possible..
U3, which is the capacitor, has a good freq response on the left leg, but the leg connected to the JFET has a bad freq response.. This I can't see why also.
The pos and negative inputs of the 3rd op amp are "bad" but it's output is good, just like the 2nd op amp, like (
)
Now, between U6 and R10, the freq response is good, but on the other leg of U6 it's already bad.
As for R15, which is connected to the 3rd and the 4th op amps, has a good freq response on the left side and a bad one on the right side.
Same goes for U7.
As we can conclude, the 4th op amp has a bad freq response on the output:
The inverting and non inverting inputs of the 4th op amp have the same response..
In this matter, both legs of R14 are bad.
R8 (Vref side) and every resistance that is making the all pass filter in parallel with the JFET, has a req response looked like the output of the pedal, but attenuated. The other leg is bad.
As for the 5th op-amp, it has a bad freq resp on the non inverting input.
The output and the inverting input are also bad
Both legs of U9 Cap are bad too (which is different from the other caps).
The 6th op-amp has at the non-inverting the freq response of the output of the pedal but attenuated:
Now as for the JFET's, in every drain point of every JFET, the response is bad. In the last FET the response is stabilized before the other ones:
In the source and the gate the freq resp of every FET are equal. They're the same as the output of pedal but attenuated:
If someone got to here and thinks he/she can help me, please say something! I'm desperate! Thank you very much
