Describe your issue:
When I plug my acoustic Ibanez with a Fishman pickup in the quad cortex, I get a loud ground hum noise on my speakers and on the headphones…I can stop it by touching the metal foot switches.
The quad cortex is plugged into two active Neumann monitor speakers via XLR. So it should be grounded…right?
The acoustic guitar is not producing hum noise when connected to a mixing desk or audio interface.
On the quad cortex I do not get the ground noise with my other instruments. My passive electric guitar, my passive bass and a passive acoustic instrument do not have this ground noise issue.
What should I do? How do I ground the quad cortex for my acoustic guitar?!?
Does the hum goes away even if you touch the jack coming out of the guitar?
I had a similar problem with my taylor and it wasn’t related to the QC but it got solved by adding a grounding plate inside the guitar
I need to apologise and give an update:
I don’t really know why, but the issue has disappeared…no more hum when plugged into my Neumann speakers.
But still, if my quad cortex is not grounded via XLR or USB, I get a ground hum.
This is the case with my active acoustic instruments playing with headphones or a battery powered amp…
When I touch the jack and my guitar strings, the hum goes away. If I connect the metal tailpiece with a metal piece with the jack output the ground hum also goes away.
Toggling the ground lift on the quad Cortex or the phase invert on my instrument doesn’t make a difference.
@PaoloM an@ thank you for your reply, yes the hum goes away if I touch the jack of my acoustic. How did you ground your guitar? Would you mind sharing explanations and pictures, please?
Question to everyone:
What would you recommend in my case?
I have done some research and found three options:
Someone came up with this grounding solution for hx stomp:
What would you do if there is no possibility to plug this into a grounded electric power strip?
Say, you have a mobile setup (quad cortex powered by a battery used with a battery powered amp on a stage without electricity - no power strip to plug it into).
Could you use a similar solution like the one of the link but with a crocodile clamp? But what would could you use to ground it on?
By the way, there’s a hidden feature to reduce hum in the Quad Cortex:
Option 2: grounding acoustic guitar
Ideas for grounding acoustic guitar with a grounding plate:
Idea for grounding acoustic guitar with a grounding bridge:
Someone also commented that installing string ferrules or a tailpiece that you connect to the jack could be easier. Connecting the tailpiece to the jack definitely works on my bouzouki.
If I understand it correctly, the instruments use my body to ground everything in this case.
Is this something I need to worry about in any way?
Option 3: going wireless
There’s a setup idea here.
In theory, no physical cable should also mean no grounding issues, right?
Maybe that’s the easiest way to go?
What do you think and what would you recommend?
I need to apologise and give an update:
I don’t really know why, but the issue has disappeared…no more hum when plugged into my Neumann speakers.
But still, if my quad cortex is not grounded via XLR or USB, I get a ground hum.
This is the case with my active acoustic instruments playing with headphones or a battery powered amp…
When I touch the jack and my guitar strings, the hum goes away. If I connect the metal tailpiece with a metal piece with the jack output the ground hum also goes away.
Toggling the ground lift on the quad Cortex or the phase invert on my instrument doesn’t make a difference.
Question to everyone:
What would you recommend in my case?
I have done some research and found three options:
Someone came up with this grounding solution for hx stomp:
What would you do if there is no possibility to plug this into a grounded electric power strip?
Say, you have a mobile setup (quad cortex powered by a battery used with a battery powered amp on a stage without electricity - no power strip to plug it into).
Could you use a similar solution like the one of the link but with a crocodile clamp? But what would could you use to ground it on?
By the way, there’s a hidden feature to reduce hum in the Quad Cortex:
Option 2: grounding acoustic guitar
Ideas for grounding acoustic guitar with a grounding plate:
Idea for grounding acoustic guitar with a grounding bridge:
Someone also commented that installing string ferrules or a tailpiece that you connect to the jack could be easier. Connecting the tailpiece to the jack definitely works on my bouzouki.
If I understand it correctly, the instruments use my body to ground everything in this case.
Is this something I need to worry about in any way?
Option 3: going wireless
There’s a setup idea here.
In theory, no physical cable should also mean no grounding issues, right?
Maybe that’s the easiest way to go?
What do you think and what would you recommend?
I wish I could tell you exactly what my guitar has had done, but I just went to my luthier and he suggested a grounding plate, I said yes, he installed it and I had no problem ever since.
Sorry for the lack of details
