Firebomb grounding

[princeton]

Hi you all.
New here, noooooob  .
I don't get how to ground input jack. Sleeve is not plugged (according to shematic). No sound. If I connect sleeve to the ground  there is sound but it got hummm.
Pedal is not in the box. May this be the problem?
I'm noob so please forgive if this question sounds silly.

[madbean]

If you are just testing the circuit outside the box and using two jacks, then connect both sleeves to ground. However, once in the box, you generally only need to connect one sleeve to ground (doesn't matter which one). Assuming you are using metal jacks, the chassis serves to ground the unconnected sleeve.

You can, of course, ground both sleeves inside the box, but there is at least the potential of a ground loop. Good practice is to have one linear path to ground, i.e. from the board to the switch to the DC jack to the sleeve of the input or output jack.

[princeton]

Great. Thanx. That makes it easier to understand.