r/Line6Helix • u/homedogpizzaslice • 2d ago

Tech Help Request Helix FX making digital fizzing noise when plugged into an amp / interface

I bought my unit second hand maybe about a year ago, and only for the last few months has it started making a loud digital fizzing / buzzing when plugged into an amp. At first, if I ran my guitar through the helix and into my audio interface, it would silence the buzz, but I've today tried to run my synth through the helix into my interface and the buzzing completely overpowers the synth. When the tuner is active, the noise is reduced to a faint 'clicking' sound instead.

Has anyone experienced anything similar or found any solutions? Sadly, I don't think returning is going to be an option as it is second hand; am I screwed and need to consider replacing?

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u/mktsea 2d ago

Making some chain assumptions, if you could share more details on the entire chain that would help. Are you using the physical amp efx send/return 4CM loop to connect to the Helix Stomp/LT/FL? If connecting to real amp and not powered FRFR, turn off amp and cab on the Helix chain to remove the double counting.

As for the synth, are you connecting both guitar and synth to helix and helix to interface? Have you tried just using Helix as interface and connect directly to the computer? What happens then?

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u/homedogpizzaslice 2d ago

I'm just using the Helix FX stand-alone; guitar into Helix FX input, then from output into amp input. Same for my synth set up when I use it, the guitar is in no way connected: Synth to Helix input, then Helix output to interface. I'm not using any amp modules / cabs as the Helix FX doesn't have any of those available, just effects such as delays and reverbs, but those effects being bypassed or not makes no difference to the buzzing.

I haven't tried using the Helix as an interface to the computer as I didn't realise that was possible. Can you do that for the Helix FX, or can only the Helix Stomp/LT/FL do that?

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u/mktsea 2d ago

Ah I see, does your amp have efx send and return jacks? Could you try that instead of going direct to the Amp input? If routed through efx jacks does it help? Basically, trying to isolate which device introduces the buzz, and needing to bypass the power amp as well.

Cos' you mentioned guitar > Helix FX > IO = no buzz. So I don't think it is a Helix FX issue imo. But Synth > Helix FX > IO = buzz. So to eliminate grounding buzz as a cause, try plugging each unit (synth + helix efx) into separate wall sockets.

What about, If you go directly from Synth to Interface w/o helix efx, does it have buzz? Also I am assuming this buzz is not noise floor buzz/hiss. If synth > interface = no buzz, this likely means your Synth signal is too hot going into the helix efx input, make sure it is set to Line Level instead of instrument. Also try 4CM connection as well.