(High) gain staging

[kylotan]

Sorry for the cross-post, but I put this over in the general Helix forum before thinking that it might be more suitable here:

 

The full detail is over there, but the short version is: if I put a distortion block before an amp block, the sound starts breaking up as if I was using a fuzz pedal. I suspect the levels might be wrong somehow, but there is also a weird phasing effect when I change the distortion pedal's level which implies something else is going on. Does anyone know what might be happening?

[kylotan]

For anyone who comes across this later, there's a lot more detail in the linked thread, but the situation is that Helix is not the only modeller or sim which shows this fuzz/bitcrusher break-up with a chain like this, but it is the only one that can't be cleaned up by pulling the output level down on the distortion sim. This supports my initial suspicion that the issue is some sort of internal gain staging mismatch, and I've filed a support ticket with Line 6 to see if they can look into it.

[soundog]

What are you using for your audio interface to get your guitar signal into Helix Native?

[kylotan]

Scarlett 6i6, 1M Ω instrument input.

 

It's not the interface, though - the same unpleasant distortion can be heard with the Helix Floor unit. Drop in a Vermin Dist with gain between 2 and 5, filter at 0, followed by a PV Panama with drive below 5 and Bass/Mid/Treble all around 5.. If you have the Vermin producing roughly unity gain, the combined sound is awful. If you pull the level down on the Vermin, the sound starts to get thin and unusable.

[soundog]

It could be a function of gain staging, as you say. Hard to say without the hardware pedal to compare. I don't use the Vermin block that often, and usually use Timmy or Minotaur if I want to shape some gain before feeding it into another distortion block. Have you tried a parametric EQ before the Rat to see what that effects? Sounds like you have useful input in the other thread (xcept "you don't know what you're doing"). Sorry I can't offer more...

[kylotan]

I've not tried an EQ, as I have no idea what I'd be doing - and I don't really want to alter my raw guitar tone, to be honest.

 

I can work around this in other ways to get the tone I want, using some other pedal and getting more distortion from the amp. So it's not a massive problem for me. I'd just wanted to take the nominal chains I'd used on other modellers for 2 previous albums - Metal Zone > Bogner Uberschall, or Rat > Peavey or Engl - and reproduce it with the newer technology. But the Helix won't play ball with either of those permutations. So right now it's really just about asking Line 6 if they know why this is happening, and perhaps they will have an idea.

[pipelineaudio1]

I remember some dsp allowing part of the dry signal through. That immediately came to mind when you said phase.  Not sure if that’s the issu here

 

exactly how line 6 does the distortion, whether straight waveshaping or some other setup might be at the heart of it.  I’ll see if there’s any experiments I can do

[kylotan]

Line6 support said "this is how it's meant to sound" so that was a waste of time.

 

I have found some sort of workaround by pulling the distortion gain down to 1.0 and compensating by pushing the level up to full. But that's not the settings I've used elsewhere so something obviously isn't modelling the original hardware very faithfully.

[pipelineaudio1]

Can you try this free Rat VST from TSE and see how it does compared to the Helix version in front of that amp?

 

https://www.tseaudio.com/software/tseR47

 

Since these plugins will be external to each other, you might well really run into actual gain staging issues, but hopefully it will shed some light and you will be able to communicate with Line 6 some apples to apples experiments and results. I don't know how responsive they are, but at least you can certainly say you've done due diligence and the ball will be in their court to make things right (if indeed things are wrong)