I just bought a new Helix Effects and now I think I have a broken unit. I have this problem, when I use 4-cable method with my tube amp:
When I use delay and volume boost at the same time, I get weird lower octave sound that makes using delay (or boost) useless. When I use only delay or only volume boost everything's ok. I have tried every possible scenario: for volume boost I have tried MXR micro amp in HXFX loop 2, after HXFX etc. and also gain block in HXFX after and before delay for about 6db volume boost. Also tried to boost delay's volume in HXFX, tried eq-pedal block with only volume boost etc. it's all the same weird sound.
Nothing's clipping and in global settings-->in/outs I have everything set to instrument, it works that way best with my amp (Marshall Silver Jubilee 2525H with -10dbv FX-loop). I have tried every possible variation with in/out settings, and they all have the same problem. I have recorded only amp and amp with HXFX 4CM in Pro Tools and with those "all set to instrument" in/out settings those recordings sound almost identical and they have almost the same volume in my daw (only amp has -8,8 db peak and amp+HXFX -8.6db peak, both recorded at the same -20 to -15db levels with amp and Reactive load+ir to daw). In my 4CM preset I have Loop1 block's all volume levels at 0 (and that way it's almost exactly the same output level than it's with only amp and guitar)
There's this same issue also if I have use my Flashback delay pedal in HXFX loop2 and try to boost volume in HXFX like mentioned before. So now I have to choose whether I use only delay or only volume boost for my guitar solos.
I've been playing guitar semi-pro for more than ten years, owned Kemper before and know something about gain staging, recording etc. so I've tried a lot different ways to try to get this work.
Here's a dropbox-link for the clip I recorded about this issue: https://www.dropbox.com/sh/n0k8zbkvi3caqqu/AABAmAS6r0Bjxryc83fqU3uja?dl=0
In this clip at first the gain block is on and about 6 db boost, then there's boost+delay, then only boost and then boost+delay off.
I have version 3.11. in my HXFX, I've triple checked the cables, gain stages etc. Hope someone could help me with this!