Hidden hum when recording from send 1

[CharAznable]

I have been trying to find a way to record an unprocessed signal and a processed signal from my Helix LT.

 

Originally I tried an ABY box with a. ground lift.  The clean channel seemed normal but it created a hum in the processed channel along with the processed signal.  If I unplugged the second cable from the ABY box there was no hum.  
 

So then I tried skipping the ABY box and using a send as the first block in the chain.  It seemed to record a perfectly clean tone in Logic Pro X.  But when I tried putting any virtual amp on the unprocessed recorded track it had the same hum as the processed track running out from the Helix LT.  

 

I could understand the ABY box having noise issues but I can’t for the life of me understand why the unprocessed send would have a hum.

[phil_m]

If you use the LT’s USB audio, you can use USB7 for the unprocessed dry signal. It’s much easier than doing with an ABY box.

[CharAznable]

What is the best way to set this up in a preset routing?

[datacommando]

5 hours ago, CharAznable said:

What is the best way to set this up in a preset routing?

Hi,

 

It’s a Global Setting, under In/Out, and always available for you to use.

 

For more information on how to use this, see:

Helix LT 3.0 Owner’s Manual - Rev D -English (also available in French and Japanese)

Page 69 -> USB Audio

 

https://line6.com/data/6/0a020a3f18374611d5dffd3a45/application/pdf/Helix LT 3.0 Owner's Manual - Rev D - English .pdf

Hope this helps/makes sense.