The silent Rat issue...

[bassmeister]

I was just wondering if anyone can explain why no sound is let through by a Rat when gain is set at minimum?

The OP amp section of the Rat is set up in a non inverting configuration. The gain for such a configuration is 1 + Zf/(Zf + Ztoground). Suffix f for feedback, and the other... OK, you get it. What would the technical suffix be?

Anyway, even if Zf = 0, which in practice corresponds to a gain pot setting at minimum, there should still be unity gain. The "1" in that formula isn't dependant of any parameter, right? :?

What am I missing?

[Stevo]

No I think you need some continuity there....put a 1K res. in series with the pot actually put a 100 K and you will have small drive a min. setting.

[bassmeister]

To cure the silence is no problem. But still, I don't get why the Rat gain doesn't behave like in an ordinary non inverting OP amp coupling?