Could this be a power supply issue?

tbm

I've a MXR DC brick running most of the pedals on my board. All the 9 volt and one of the 18 volt outputs are being used. Of late I've noticed a loud pop when I engage pretty much any of the pedals. Is this the power supply or could it be the power in the room?

Cirrus

As far as I know, those kind of pops are usually caused by a voltage offset in your signal chain. If you have true bypass pedals, when in bypass the guitar signal happily rides along with the offset. Then when you stomp on a pedal the signal is grounded and you get a click in the signal as the voltage goes from, say, +0.8v to 0v.

The culprit could be a few things. DC on the amp's input jack, a buffered pedal not playing nicely, god playing tricks on you...

tbm

Thanks. Something to investigate. I reckons it's God though, the bollox.

photek

Might sound silly but have you tried stomping on them all before you switch the power supply to them on? I had the same issue with one of my board layouts and most of the time this rectified it. Something to do with static I was told.

benvall

Cirrus said:

As far as I know, those kind of pops are usually caused by a voltage offset in your signal chain. If you have true bypass pedals, when in bypass the guitar signal happily rides along with the offset. Then when you stomp on a pedal the signal is grounded and you get a click in the signal as the voltage goes from, say, +0.8v to 0v.

The culprit could be a few things. DC on the amp's input jack, a buffered pedal not playing nicely, god playing tricks on you...

+1

I had a few pops when I had a true bypass delay pedal last in my chain. I moved it so I had a buffered bypass pedal last and the pop went.

ICBM

If all the pedals are true bypass and you get the pop - or putting a buffered pedal last cures it - it's almost certain there is a DC leak from the amp's input valve. In vintage designs these are usually DC-coupled to the input jack.

Try replacing V1 in the amp. If it fixes it you can still most likely use that valve in another position - in fact if you don't have a spare valve, just try swapping V1 with any other 12AX7 in the amp.