UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Mullard 3-3 voltages query

Boulevardier · 8th Apr 2021, 9:26 pm

You didn’t forget to fit the 10MΩ grid-leak resistor on the EF86, did you? I’ve done that myself with this amplifier - easy to miss because in many/most input circuits you might be expecting the grid to get a DC path to ground through the volume control. But in this circuit the v.c. is AC-coupled to the grid, so the valve really needs that 10MΩ to ground.

Mike

8th Apr 2021, 9:26 pm	#5
Boulevardier Octode Join Date: Sep 2017 Location: Bristol, UK. Posts: 1,657	Re: Mullard 3-3 voltages query You didn’t forget to fit the 10MΩ grid-leak resistor on the EF86, did you? I’ve done that myself with this amplifier - easy to miss because in many/most input circuits you might be expecting the grid to get a DC path to ground through the volume control. But in this circuit the v.c. is AC-coupled to the grid, so the valve really needs that 10MΩ to ground. Mike