If you call yourself a proud owner of the Mooer Micro ABY mk2, congratulations, because it’s a great and cheap solution for ABY switching on or next to your pedal board.
However, if you want to use the Micro ABY with one guitar and two amps, you might run into a significant problem, a ground loop. Well, at least I did. Both outputs A and B of the Micro ABY will share the same ground and since they are connected internally, create a ground loop. The most significant symptom of a ground loop is annoying hum. Yes, even more annoying than the hum coming from a strat.
Now, there are several cures to hand, so be not afraid. Most of the fixes will basically attempt to break the loop. This can be done by either
- a ground lift
- a transformer
- a DI box
An in depth article about ground lift methods can be found at TI.
As of today, I’ve successfully built 3 DIY guitar effects pedals and I thought to myself, how can I patch the Mooer ABY? At first I tried to mod it, add a ground lift switch or a 10Ohm resistor. But then I thought, why not just physically break the loop?
If you open up the pedal, you will find the two output jacks for A and B. I simply snipped off the ground lug of output jack B. That’s it.
Yes, it is invasive, but I didn’t care, because it’s a cheap pedal and I use it in a dual amp setup only.
However, keep in mind that this change has a couple of effects or things you have to consider before doing this:
- It’s invasive and kind of irreversible and will definitely void warranty of the pedal
- If you connect only one output to the pedal, it has to be connected to the output WITH the ground still connected, obviously. In my case, for instance, the two amps I use are the Strymon Iridium and an external tube head. Most of the time, I actually only have the Iridium connected. So I connected the Iridium to output A. And whenever I want to add in the external tube head, I will connect that to output B (i.e. the one without ground)
- I haven’t tested what happens if you use the pedal in the opposite direction, i.e. using two guitars and one amp
Disclaimer: This is just a tip for people who know what they’re doing, I’m not responsible for any damage on your gear.
Note: Do never break the ground cycle on the AC side or on a wall plug, because it’s very dangerous!