How do bias resistance, voltage and current depend? (wiring bias pot)

[BlueX]

As I understand, bias voltage (U-bias) close to 0 will give high bias current (I-bias), and vice versa (big negative U-bias gives low I-bias).

Also, to get big potential difference you should have high resistance.

So, if I want to wire the bias pot so that I get high I-bias when turning it clockwise, should I then wire the pot to get lowest resistance when turned clockwise?

Is there any prefered way to do this?

 

[FleshOnGear]

I’m not a tech, so keep that in mind…

Usually the bias voltage runs through a voltage divider. In a Super Lead, the bias voltage is divided by a 15kohm resistor in the upper leg, and a 47kohm resistor in series with a 22kohm pot in the lower leg. When you turn the pot totally CW, the voltage divider is 15k over 47k (which gives you the smallest negative bias voltage and highest current), and when it’s totally CCW it’s 15k over 69k (which gives you more negative voltage and lowest current).

If you wanted to increase the upper current range of your bias control you could possibly change the pot to a 50k pot, and the 47k resistor to 22k resistor. The downside is that your adjustments will be fussier. Smaller movements of the pot will be required to zero in on your desired bias setting.

If you wanted to increase the lower current range of your control you’d have to reduce the 15k resistor in the upper leg of the voltage divider.

Does this help? Or did I muddy the waters even more? Btw, since I am not a tech, I will say that I’m just giving these examples to illustrate how the voltage divider affects the bias; I am not advocating making those changes, at least not without knowing procedures to safely confirm that you have an appropriate bias voltage applied to your tubes. Why do you need a change from the standard bias circuit?

 

[BlueX]

Usually the bias voltage runs through a voltage divider. In a Super Lead, the bias voltage is divided by a 15kohm resistor in the upper leg, and a 47kohm resistor in series with a 22kohm pot in the lower leg. When you turn the pot totally CW, the voltage divider is 15k over 47k (which gives you the smallest negative bias voltage and highest current), and when it’s totally CCW it’s 15k over 69k (which gives you more negative voltage and lowest current).

Thanks! This seems to confirm my assumption.

 

[BlueX]

Why do you need a change from the standard bias circuit?

I'm not trying to change the circuit. Just wanted to know how to orient the pot. If I swap places for the outer lugs the pot will act in the opposite direction ("100% to 0" instead of "0 to 100%").