Hey there @red, I'm pretty sure you're going to hear a loud noise any time you disconnect the output cable of a pedal if that cable is connected to your amplifier and you haven't put the amplifier in standby.it also make a loud noise when I disconnect the output
Do you have any of the other 3 working builds handy? Can you check the voltages on those with your voltmeter to see if the voltages on the non-working build are similar?i've built 4 skeptical buffers, 3 of them work, the last one not, I've checked and it gets 17v on the tl072, I think it could be the problem