Catalinbread sft V2 clone

[Atodovax]

Hello forum, i have a question. Im building a sft v2 clone from effects layout blogspot. I used 2n4393 transistors and every thing seens right my quedtion is this. On stoner mode with gain maxed i i put too much bass and little treble, the higher notes of my guitar Will fade and became gated. Is that something normal in this pedal? . Also there is a diode labeled 1n4002 i replaced ir with a 1n4007 is that only forma current protection ir can it be affecring sound? Thank you very much. Here is a video of the pedal so you can hear the sound. At the end i max the gain and bass and you can hear the notes gated
https://youtu.be/BtskvlhQmTE