[fryzz]

In the guitar amp built for nephew I also used a 'single' connection
on the bias pot wiper but the configuration is different. The pot ends
go to -Bias and the grid resistor with the wiper going to ground
through another resistor. -Bias through the pot and ground resistor
then forms a variable divider but if the wiper breaks contact bias
goes full negative so it's 'fail safe'.

Excellent!