Cherrybomb ground noise when guitar volume is rolled back

[garfo]

I've build and rebuild this circuit and got to some conclusions.
I've built it stock, only change was changing the 220p cap for a 500 cap, and changed the 47uf cap for a 100 uf since I was experiencing some overall noise.
Transistors are Q:1 BC547A Q:2 BC547A, Q:3 BC457B

(I've reset the bias of Q2 to around 3.5 volts. It sounds good that way and I've also took readings from an original Colorsound that was custom built for a friend.
His pedal is different from all the other schematics since it appears to have an extra section with an F245A transistor. Main difference is that it sounds fuller and it has less gain.)

The thing is, as it occurs with most Fuzzfaces, this pedal is making a lot of noise when the guitar volume pot is rolled off completely. Is this normal? My friends original doesn't do this.