G Bus THRESHOLD sensitivity

The THRESHOLD control is one of the few places that the G Bus circuit departs from the original console schematic. This is because, in the years since the console was designed, the world has switched to digital recording and, as a result, works at higher signal levels. So the THRESHOLD control on the G Bus is dialed in to be less sensitive than the original.

So, if you tend to mix "quiet" or are using an all-analog setup, you may want to make THRESHOLD more sensitive. To do this, you can adjust R3_CB or both R3_CB and R4_CB.

• R3_CB sets the maximum sensitivity. Decreasing R3_CB makes THRESHOLD more sensitive, while increasing R3_CB makes THRESHOLD less sensitive at the CCW end of the pot. You can think of decreasing/increasing R3_CB like turning the THRESHOLD pot CCW/CW.
• R4_CB sets the minimum sensitivity. Decreasing R4_CB makes THRESHOLD less sensitive, while increasing R4_CB makes THRESHOLD more sensitive at the CW end of the pot. You can think of decreasing/increasing R4_CB like turning the THRESHOLD pot CW/CCW.
• R2_CB adjusts the taper of THRESHOLD so that the "sweet spot" is wider. In most cases it's better to leave it as-is.

Fair warning, the stock values were arrived at after much gnashing of teeth and pulling-out of hair. Being a passive network, every resistor in the THRESHOLD circuit affects every other. So you may decrease R3_CB only to find that the control is now too sensitive at the CW end, in which case you need to decrease R4_CB, which in turn makes the CCW end less sensitive, etc. So I recommend replacing R3_CB and R4_CB with trim pots to start, so you won't be replacing resistors too many times. And if you land on a group of settings you really like, please let us know so we can post them here for other users.

Additional Resources:

• G Bus Schematic (PDF)