Hi DIYAUDIO Friends , I make transistorized tone control (TC-TB3 Namec), It's working but l have little issue. When
I put this preamp on a surface little hum sound though speaker
, but when I lift preamp in air (air gap from surface) hum sound goes so far back. I used this preamp or tone control with AX11 and many other amp result same.
How can I solve this issue.
PCB layout and ready PCB pic uploaded.
I put this preamp on a surface little hum sound though speaker

How can I solve this issue.
PCB layout and ready PCB pic uploaded.