Help!! Severe Ground Loop Noise When Using Black Box Mini with Effects Pedals

[Chao Kang Lee]

I just received a brand new Black Box Mini last week, but whenever I connect it to my effects pedals, I get severe ground loop noise.

My signal chain is:
Pedal Steel Guitar → BB Mini (powered by the original wall adapter) → Tuner → Volume Pedal (powered by a Strymon power supply).
Everything is plugged into the same power strip.

Does anyone know why this is happening?
How are you using your Black Box Mini?
Please help me — thank you!

[Kevin Hatton]

Obvious answer is why don’t you call Brad Sarno and ask him. He knows.

[Chao Kang Lee]

Obvious answer is why don’t you call Brad Sarno and ask him. He knows.

I’ve already sent an email to Brad, but I’d like to know how other people are using it and if anyone else has encountered this issue.

[Rich Ertelt]

I've run mini - od pedal (a Kingsley so on its own power supply) - telonics pedal on its own power and had no issue.

I can't see it being an actual loop, as there is no ground on the mini power supply.

Does it do it without the volume pedal and fx?
Does toggling the switch on the mini make any dif?
Does it do it with the volume pedal powered by something else?
I would try it with just those 2, no fx pedals, and see what happens.

It really is a matter of the process of elimination. Use different cords. Try one pedal at a time. stuff like that.

[Steve Lipsey]

Have you tried reversing one of the power supply plugs in the outlet, assuming that one of them is a two-prong plug? And making sure that the amp is also the same polarity? That works for me...

[Fred Treece]

My signal chain is:
Pedal Steel Guitar → BB Mini (powered by the original wall adapter) → Tuner → Volume Pedal

And then what?

First, follow Rick Ertelt’s advice on process of elimination.

Isolate the BB. Just run the guitar into it and then straight into your amp.

If all is well, start adding things back into the chain one at a time.

If you run an OD or Dist pedal in your chain and it turns out to be the guilty culprit, try putting it in front of the BB.

[Chao Kang Lee]

I've run mini - od pedal (a Kingsley so on its own power supply) - telonics pedal on its own power and had no issue.

I can't see it being an actual loop, as there is no ground on the mini power supply.

Does it do it without the volume pedal and fx?
Does toggling the switch on the mini make any dif?
Does it do it with the volume pedal powered by something else?
I would try it with just those 2, no fx pedals, and see what happens.

It really is a matter of the process of elimination. Use different cords. Try one pedal at a time. stuff like that.

Thank you, Rich. When using the BB Mini alone (PSG → BB → interface), everything is perfectly quiet. However, as soon as I connect a tuner or volume pedal after the BB, it introduces noticeable noise. I've ruled out many possible causes, and the noise isn't coming from the downstream devices themselves—they are completely quiet when used on their own.
I've also swapped out all the cables, so I can rule out any issues related to the wiring as well.

[Fred Treece]

Could be a bad 12ax7. And definitely get one straight from Brad.

[Dennis Detweiler]

If you are using a separate power supply for the BB, try using the Strymon supply for everything? Or try using a two-prong adapter on the Strymon if it has a three-prong plug?

[Rich Ertelt]

Thank you, Rich. When using the BB Mini alone (PSG → BB → interface), everything is perfectly quiet. However, as soon as I connect a tuner or volume pedal after the BB, it introduces noticeable noise. I've ruled out many possible causes, and the noise isn't coming from the downstream devices themselves—they are completely quiet when used on their own.
I've also swapped out all the cables, so I can rule out any issues related to the wiring as well.
[/quote]
What happens when you use a different power source for the FX or Pedal? Just use one device, for testing, say the volume pedal.

There is a toggle on the mini, what happens when you move it? What position is it in now?

You say you are plugging into an interface, so I assume you mean direct. What happens when you plug it into a different input or plug it into an amp?

[Chao Kang Lee]

Thank you, Rich. When using the BB Mini alone (PSG → BB → interface), everything is perfectly quiet. However, as soon as I connect a tuner or volume pedal after the BB, it introduces noticeable noise. I've ruled out many possible causes, and the noise isn't coming from the downstream devices themselves—they are completely quiet when used on their own.
I've also swapped out all the cables, so I can rule out any issues related to the wiring as well.

What happens when you use a different power source for the FX or Pedal? Just use one device, for testing, say the volume pedal.

There is a toggle on the mini, what happens when you move it? What position is it in now?

You say you are plugging into an interface, so I assume you mean direct. What happens when you plug it into a different input or plug it into an amp?
[/quote]

I tried powering the Black Box using the same power supply as my other pedals (Strymon), and the ground noise completely disappeared. So I believe the issue was a ground potential difference between the original wall wart and the Strymon-powered devices downstream.
But what's strange is that it seems like I'm the only one experiencing this issue.

[Fred Treece]

…

[Bob Sigafoos]

I have an old school Black Box that caused a big ground loop hashing noise in any of my tube amps. This drove me nuts for a while untiI I isolated the problem. I bought a Srymon power supply for my five pedals thinking it was the problem for a ground loop but it was no use. My Black Box plugs into 117 volts and was different from the pedal power supply. The last thing I tried was a HUM/X plug in thingy for the Black Box. Problem solved.

[Marshall Woodall]

I'm sure you tried this but did you pull the tuner alone out of the equation?

[Rich Ertelt]

I tried powering the Black Box using the same power supply as my other pedals (Strymon), and the ground noise completely disappeared. So I believe the issue was a ground potential difference between the original wall wart and the Strymon-powered devices downstream.
But what's strange is that it seems like I'm the only one experiencing this issue.

Glad you got it sorted. You might want to drop Brad an email, he might know something.

That is odd. The BB Mini has a wall wart, so there is no ground. Also, it is a transformer, so it should be electrically isolated on the power side. So it isn't really a ground loop I don't think, at least through the power. You could try a ground lift on the Zuma, just to see.

Could be some type of leakage to the ground/shielding on the chords. I do know Strymon talks about noise and cords. I used to have an Ojai but it kept breaking, so I went Cioks. Didn't have any noise issues though. And I was using tube OD pedals, so tubes like the BB.

https://www.strymon.net/faq/getting-noise-using-zuma/

[Chao Kang Lee]

Yes, I’ve already been in touch with Brad, but he said he’s never encountered a situation like mine before. I still haven’t been able to resolve this damn noise issue, and it’s been extremely frustrating.

[Patrick Huey]

What tuner are you using? I had issues using my Peterson strobe hd if it was plugged into my pedal power brick’s usb port. Also I have an external 9v battery adapter that will let you plug a 9 V battery into the external power input of pedals and I have found that using it helps tremendously for tracking down pedals that use 9v that are noisy when plugged into wall power.