Dr. Boogie/Amp sim Question

[WGTP]

The small caps, 220pF in Dr. Boogie, that are attached from the gate to the source for the JFet/Tubes are for negative feedback and reduction of the highs, I'm guessing???  Thanks. 

[Davelectro]

HF reduction. Yes.

They should go to ground, really...but it seems that when you have large bypass caps you get the same effect.

[PRR]

> should go to ground

Source impedance is generally SO much less than drain impedance that "source is as good as ground within 10%".

[WGTP]

Thanks gentlemen, another spot for EQ tweaks. 

[Caferacernoc]

Same idea as a "snubbing" cap in parallel with the plate resistor in a tube amp or tube amp sim. Reduces just enough highs to hopefully prevent oscillations in a high gain amp. But can also be used for tone shaping. I think the 220pf value comes from the Fetzer valve article. It was used to simulate miller capacitance to keep out RF signals and further emulate the tube triode sound.