Helix LT 1/4" output problem

[GhaussyDreams]

Hi, I have a problem with my Helix LT's outputs.

 

Short version: The 1/4" output have horrible distortion when set to line level and into FOH mixer.

 

Long version: I have a somewhat complicated setup on my Helix LT. I have a guitar running in on one path and a bass on another. The guitar goes to 1/4" outputs, from there TRS to a stagebox, then one side to an Behringer XR18 (IEM mix), the other side to an Art P16 patchbay and from there to a mixer (FOH mix). The bass goes to XLR outputs and then the same route. Bass on the XLR sounds fine and guitar sounds fine in the IEM mix, but FOH mix sounds horrible distorted.

Things I've tried:

 

Updated Helix LT, factory reset and the loaded my preset back in.

 

Tested different port on stagebox, patchbay, different cables and different channel on mixer. Went simple and hooked the Helix LT straight from the 1/4" to the mixer.

 

Looked though all the global settings and checked the global EQ is off. When I choose instrument level on the 1/4" output the FOH mix is okay, but real quiet and impossible to boost with preamp gain without loads of white noise. On line level there's horrible distortion.

 

Checked there is no input clipping on the Helix LT, not clipping on the output, no clipping on the mixer channel.

 

If I switch the guitar preset to the XLR everything sounds fine.

 

If I switch the bass preset to the 1/4" there's no distortion, but it sound very dull and low volume.

 

It seems like the 1/4" outputs are somehow faulty, but I don't get how the IEM mix through the XR18 sound perfectly fine, while the exact same output to a FOH mixer sounds absolutely terrible. Any ideas towards a solution? The only thing I've come up with yet, which I haven't tested is running Multi output on both guitar and bass path panning them hard left/right and the have the XLR output to FOH and the 1/4" to my IEM mixer.

[phil_m]

It doesn’t sound like the 1/4” outs are to blame if you’re saying they sound fine going into the XR18. It sounds like something is happening with the FOH mixer. Are you sure you’re not clipping its inputs? If the mixer isn’t set up for line level inputs, it’s pretty easy to clip those channels. Even if they are, the LT is capable of outputting a pretty hot signal.

[GhaussyDreams]

The mixers clip indicator doesn't light up and XLR line level from the Helix doesn't give any problems. But yeah it's very weird to me how the signal going to the XR18 sounds fine, but if I unplug that and put it straight into the FOH mixer it distorts very badly. Was hoping I had overseen something you guys could maybe catch onto. But if I take the bass path on the 1/4" instead it's also so much quieter and weak sounding compared to the XLR even though they are both on line level... no distortion though.

[phil_m]

What is the make and model of the FOH mixer?

[GhaussyDreams]

Peavey XR1212. Have another Helix hooked up to it via 1/4" and the bass path from my own via XLR with no problems. Also I tried another channel that I know works, but still this horrible clipping/distortion on the 1/4" guitar path.

[GhaussyDreams]

I'm used to having combo XLR/Jack on the XR18, so I think my problem comes down to how I wire the Helix to the FOH mixer. Next time I'll try and wire it up properly through the line jacks and see if that cures the problem. This is clearly a fault, but I still don't understand why it works fine with keyboard, bass through Helix LT, guitar through Helix, but guitar through the Helix LT is all distortion. Well at least I got something that might fix my problem =)

[DunedinDragon]

A couple of big differences here could be related to signal level differences between XLR and 1/4" and the differences in how signals are handled in modern digital mixers and in older analog mixers.  There's a significant difference between the XR18 which is a modern digital non-amplified mixer with digital pre-amps that can accommodate a wider range of signal level inputs and outputs from either a XLR or 1/4" input to be used with powered speakers, and a last generation Peavey amplified mixer with separate XLR and Line inputs which typically are used for different signal level inputs and outputs an amplified signal to passive speakers.  You didn't say what signal levels you're sending on the XLR and 1/4" outputs from the Helix.  Typically they're both set to line level by default, but I always set my XLR to Mic level (which is a lot lower than line level) and leave my 1/4" output at line level.  But in your case it's hard to predict what's going to be correct because of the differences between the architectures of the two mixing boards.  It's very possible you're getting an overdriven signal at the Peavey preamp stage.  You said it's not showing clipping, but unless you select the PFL button on that channel you wouldn't see the preamp clipping.

Given all the differences in the setup it's really impossible to guess what's happening in this situation without a LOT more information.

[GhaussyDreams]

Both the XLRs and 1/4" are line level. I hooked it up properly through the line inputs in the mixer and everything sounds good. Still don't understand why the XLR line level on my Helix LT and the other Helix Floor 1/4" line level sounds fine in both the mixers mic and line input, but the 1/4" on my Helix LT only works in the mixers line input... but maybe I shouldn't think too much about that, since I found a solution =)