Nano Cortex ground issue

[Desertdweller]

When I plug my NC direct to my computer, or with headphones, there’s no problem.

When I plug it through a power amp into a cabinet, I hear a distinct ground loop noise. It’s not terrible, but it’s there. I can tell it’s a grounding issue because if I put my finger on the NC, the noise goes away as it’s grounding through me.

I have it hooked up on a pedalboard using a TrueTone One Spot CS6 and it takes up 2 500ma plugs on the CS6. It’s the only pedal drawing power from the CS6 right now. The power amp doesn’t have noise if I use it by itself, the NC doesn’t have noise if I use it through a PC or headphones, but the NC and the power amp connected to a cabinet creates a grounding issue for the NC where it’s ungrounded. This does not happen with my FM9, but it has a grounded IEC plug.

Any ideas how I can fix this?

 

[Progressive_disclosure]

I’ve had my Nano for a few weeks but haven’t played it through a power amp and cab yet. I’ll try to replicate this tomorrow if no one else has any good answers before then, and see if it’s the same for me!

 

[Progressive_disclosure]

So I fired it up now, powered from my Harley Benton PowerPlant ISO-5 Pro using one 500mA outputs (so now I know that it works to power the Nano as well). I removed everything else it was powering except an overdrive since it would be a hassle. Plugged guitar directly into Nano and then an instrument cable from output L to the FX return of my tube amp (Fireball 25). Amp is connected to a 1x12 V30.

Fired up some high gain captures and lost some time playing. Also turned down the input gate to check. Whisper quiet both with ground lift engaged and not. There was a clear volume difference though but no hum or noise whatsoever even with high gain captures. Guitar has older Fishman Fluence Moderns but also tested coil split and the noise was negible. Much quieter than running my pedals and preamp!

I ran it pretty loud, can feel it in my ears now, so louder than bedroom levels.

Don’t know how much this helps but the unit should be quiet in that setup. When I did the same with an HX Stomp there was a lot more noise!

 

[Lysander]

When I plug it through a power amp into a cabinet, I hear a distinct ground loop noise. It’s not terrible, but it’s there. I can tell it’s a grounding issue because if I put my finger on the NC, the noise goes away as it’s grounding through me.

I had similar issues with the original QC back in the day. The only reliable solution i found was having an external ground attached at all times - in my case, via a USB-B connection to a computer.

 

[mbenigni]

When I plug it through a power amp into a cabinet, I hear a distinct ground loop noise. It’s not terrible, but it’s there. I can tell it’s a grounding issue because if I put my finger on the NC, the noise goes away as it’s grounding through me.

This might be a stupid question, but have you got the power amp plugged into the same circuit (preferably the same outlet or power strip) as your NC? I can duplicate the symptoms you describe here with my QC if I have my power amp plugged into a different outlet; I figure this is just a ground variance in the house wiring.

Another thing I've noticed is that, when I have a grounding issue, some guitars call it out more so than others. I'm guessing those guitars have ground wire issues of their own?

 

[mbenigni]

I had similar issues with the original QC back in the day. The only reliable solution i found was having an external ground attached at all times - in my case, via a USB-B connection to a computer.

USB-B connection to a computer as a solution surprises. A USB connection often presents a different sort of digital noise. I have to use a filter on my laptop to keep it quiet. (Not QC specific - same trouble with my HX Stomp back when.)

 

[bucephalus]

USB-B connection to a computer as a solution surprises. A USB connection often presents a different sort of digital noise. I have to use a filter on my laptop to keep it quiet. (Not QC specific - same trouble with my HX Stomp back when.)

Yeah same for me, when connected to laptop I get quite a bit of noise. What filter are you using? Do you think one filter with a y cable could do two usb connections (from tonex and hx stomp)?

 

[mbenigni]

Yeah same for me, when connected to laptop I get quite a bit of noise. What filter are you using?

Good question, since lots of them suck. (Some do nothing in terms of attenuating noise, and some fail to establish a USB connection at all... which is one way to solve the problem I guess? )

The price range for these things is really wide. Being the cheapskate that I am, I ran through a bunch of $20 options (that sucked) before finally settling on this one, for $40. It resolved the issues with my specific laptop/ USB port, though YMMV:

Do you think one filter with a y cable food do two usb connections (from tonex and hx stomp)?

Hard to say. If you have a USB hub/ y cable that the ToneX and HX Stomp are otherwise working OK on, then I would guess so (provided neither are reliant on bus power?) But there's also the possibility of noise from one back-feeding to the other.

$40 and a generous return policy... trial and error is the way.

 

[bucephalus]

Good question, since lots of them suck. (Some do nothing in terms of attenuating noise, and some fail to establish a USB connection at all... which is one way to solve the problem I guess? )

The price range for these things is really wide. Being the cheapskate that I am, I ran through a bunch of $20 options (that sucked) before finally settling on this one, for $40. It resolved the issues with my specific laptop/ USB port, though YMMV:

View attachment 59730


Hard to say. If you have a USB hub/ y cable that the ToneX and HX Stomp are otherwise working OK on, then I would guess so (provided neither are reliant on bus power?) But there's also the possibility of noise from one back-feeding to the other.

$40 and a generous return policy... trial and error is the way.

Thanks, appreciated.

Bizarrely that the exact one I had in my Amazon basket earlier today...

 

[mbenigni]

Bizarrely that the exact one I had in my Amazon basket earlier today...

If that doesn't do the trick, it's likely two of them will?

 

[dean701]

Masking tape will do the same for free. :)

 

[bucephalus]

Masking tape will do the same for free. :)

Explain please?

 

[dean701]

If you have device (modeler/profiler) that has a power adapter connection, plus an audio cable connection to a soundcard, plus a usb connection to a computer, plus connections to other audio pedals/gear, it now has a few ways to find ground. Depending how those other devices are grounded, they can also have multiple paths to earth ground. When you have too many grounds that can create loops.

Loops can be avoided by removing grounds from the equation and stopping the loop. Most of these add-on connectors/amazon adapters are simply opening up the ground pins on the USB connections. The same can be done by putting tape over the ground/power pins on the usb connectors. Similarly some devices have ground lifts which can help.

Other issues can happen if there is no ground at all. That's a completely different problem where you need to add a legitimate earth ground to stop hum. In the OP situation, an XLR cable from the Nano to a grounded device plugged into the same outlet usually fixes the lack of ground.