Question about the Crossover split - known issue?

[ZiggyZipgun]

Has anyone else noticed that certain effects or amps will combine the inputs and apply the crossover at the end of the individual signal paths?

 

My guitar is wired in stereo so I can route the neck and bridge pickups to different channels, and there lots of great tones to be found by combining the top end of one pickup with the low end of the other (I'm currently splitting at 875hz). This works well until I turn on any blocks in the individual paths, and then it's clear that both inputs are combined before being split into high and low channels. Some legacy effects don't cause this issue, but it seems that all non-legacy effects do.

 

Is this a known issue?

[Schmalle]

Try the stereo fx.

 

From the Stomp's manual:

Quote

Block Order and Stereo Imaging

 

The signal path in HX Stomp is stereo, carrying two channels of audio. When the device is fed a stereo input source (i.e., when discrete left and right signals are connected into the HX Stomp Left and Right input jacks), the source audio is processed discretely in stereo wherever stereo blocks are used within the path. Whenever a mono block is added within a path, both channels of audio are combined and sent out of the block as mono.

 

Most of the effects models in HX Stomp have both mono and stereo versions. A stereo block displays after its model name in the inspector. The stereo imaging—or how wide your tone appears with stereo speakers or headphones—is highly dependent on the type of blocks you add and in what order.

 

Legacy effects models vary in behavior, just as on the classic Line 6 effects from where these models originated.

• Legacy Distortion, Dynamics & Pitch/Synth effects are mono
• Legacy Modulation & Delay effects vary in that some are mono, some stereo, and some mono in/stereo out, where adjusting the effect’s Mix parameter can narrow the stereo image fed into them. It’s best to experiment with these effects and tweak the Mix parameter to achieve the desired stereo output results

• Legacy Filter and Reverb effects are stereo

 

[ZiggyZipgun]

I just tried it, and the stereo blocks do keep the high and low paths separate - but these blocks are placed in one path or the other, where you could not have a stereo signal when using the crossover.  When two inputs are used, it will send one to the high and one to the low, and that's what I'm trying to maintain.  The stereo distortion, modulation, and delays blocks in each path will help, but they will eat up more DSP, and since there are no stereo amp or preamp models, we're not able to create a proper bi-amping patch the way many bass rigs are built.

[Schmalle]

I'm not sure what you want. If you want to use effects on the lows and highs individually you can do that on their individual paths between the Crossover Split and the Mixer.

 

The Crossover Split does what it's supposed to do. Say you use it and then combine both paths into one again with the lows on one side (L or R) and the highs on the other (by panning in the mixer block). If you then use a mono block both sides (L and R) are summed to a mono signal at the input of that block. That's not an issue, that's expected behavior.

[datacommando]

On 7/6/2026 at 5:45 PM, ZiggyZipgun said:

since there are no stereo amp or preamp models, we're not able to create a proper bi-amping patch the way many bass rigs are built.

Hi,

 

Hmm… there is a guy here who would beg to differ on that point. Although, he uses a mono output bass into a Helix LT, it is only using the top 2 paths 1A & 1B, it should work on a single DSP Stomp, or Stomp XL.
 

Check this video from 11:49 - everything before that you would probably already know, regarding traditional bi-amping techniques.

 

Hope this helps/makes sense.

[ZiggyZipgun]

On 7/8/2026 at 12:05 AM, Schmalle said:

The Crossover Split does what it's supposed to do. Say you use it and then combine both paths into one again with the lows on one side (L or R) and the highs on the other (by panning in the mixer block). If you then use a mono block both sides (L and R) are summed to a mono signal at the input of that block. That's not an issue, that's expected behavior.

Certainly any mono block placed after the Mixer will combine both signals.  But when splitting two inputs with the crossover, you have to set the Mixer panning to hard left and right to keep the inputs separated, and placing any mono block (and some stereo ones) in Path A or B (before the Mixer) will automatically combine both inputs before the crossover.  

 

On 7/8/2026 at 4:43 AM, datacommando said:

Hmm… there is a guy here who would beg to differ on that point. Although, he uses a mono output bass into a Helix LT, it is only using the top 2 paths 1A & 1B, it should work on a single DSP Stomp, or Stomp XL.

Yeah, not an issue with one input.  And not a issue with the Y-split, sending two inputs to separate amps.  But using one pickup for highs and one for lows gets tricky!

[Schmalle]

On 7/8/2026 at 7:50 PM, ZiggyZipgun said:

Certainly any mono block placed after the Mixer will combine both signals.  But when splitting two inputs with the crossover, you have to set the Mixer panning to hard left and right to keep the inputs separated, and placing any mono block (and some stereo ones) in Path A or B (before the Mixer) will automatically combine both inputs before the crossover. 

That is all expected behavior.

If you want to "create a proper bi-amping patch the way many bass rigs are built" nothing is stopping you from doing that after the split (usually a hard left-right panned Split Y, but a Crossover Split can also work - although it seems a bit radical). I mean you would set amps differently and probably choose different amps in a bi-amping situation anyways, wouldn't you? There are some very little DSP demanding amp sims like the Del Sol 300 if needed. https://benvesco.com/store/helix-dsp-allocations/

[datacommando]

On 7/8/2026 at 6:50 PM, ZiggyZipgun said:

Yeah, not an issue with one input.  And not a issue with the Y-split, sending two inputs to separate amps.  But using one pickup for highs and one for lows gets tricky!

Ah!
 

Originally I should have asked how you are actually physically connecting your neck and bridge pups to your Helix, HX Stomp, (or whatever - you didn’t mention). I’m guessing it’s a Stomp, which has a Left/Right stereo input option.

 

If you were using a Helix Floor this would be a lot easier - tools for the job.

 

Hope this helps/makes sense.

[ZiggyZipgun]

On 7/8/2026 at 4:45 PM, datacommando said:

If you were using a Helix Floor this would be a lot easier - tools for the job.

The Helix Floor and LT have aux inputs, but the impedance matching is not applied to that aux input.  The Stomp and XL are the only units that apply it to both inputs, and I do use it a lot - often set ~136 hz.  I run a second Stomp in the FX loop just for reverbs, since I use the dynamic split to shift between two parallel stereo reverbs.  The Stomp produces enough latency that you will notice it if you use it for anything other than delays and reverbs, so I keep that second unit 100% wet and blend it on the first unit.

 

On 7/8/2026 at 11:25 AM, Schmalle said:

That is all expected behavior.

Well, it's not - it's not even consistent behavior from one effect to another.  I can run a different phaser/flanger/chorus on each path and keep the pickups separate, no problem; switch one to a rotary cabinet and they're suddenly blended together (before the split).  You were certainly right when you suggested using the stereo effects, but it doesn't work for every model, and that's not the behavior I would expect after using 5 generations of Line 6 modelers over the past 20 years.

 

On 7/8/2026 at 11:25 AM, Schmalle said:

I mean you would set amps differently and probably choose different amps in a bi-amping situation anyways, wouldn't you?

They're less common now, but there were bi-amping bass combos that had a crossover built in, and that's easy to emulate with one input.  And a number of famous custom rigs sent different pickups to different amps, and that's easy to do with the Y-split.  Now I know these can be combined, even if it is definitely an edge case scenario.  It does have a unique benefit of being able to really combine two different pickup sounds into one, rather than layering, and it works equally well on my fretless P-bass with a mudbucker in the neck, my Jaguar tuned from A to A in all 5ths, and my Tele-ish Godin Session Custom tuned down to C# standard.  I've been using the Y-split for a few years, and it's pretty sweet to be able to save my pickup selection in each patch, flip the phase of a pickup with a footswitch, or switch from the neck to the bridge with an expression pedal.

[ZiggyZipgun]

On 7/12/2026 at 9:40 AM, ZiggyZipgun said:

...it's not even consistent behavior from one effect to another.

Chorus?  No problem.  70s Chorus?  Merged.  Reto Reel?  No problem.  Doubler?  Merged.

Very inconsistent, but probably due to DSP handling.  Each model uses a different amount, but I have no issues running an extra preamp, an amp, and a dual cabinet, along with and drives, modulations, and delays in each of my patches.  Separate amps and cabinets does limit the selection.

[Schmalle]

On 7/12/2026 at 6:40 PM, ZiggyZipgun said:

Well, it's not - it's not even consistent behavior from one effect to another.  I can run a different phaser/flanger/chorus on each path and keep the pickups separate, no problem; switch one to a rotary cabinet and they're suddenly blended together (before the split).  You were certainly right when you suggested using the stereo effects, but it doesn't work for every model, and that's not the behavior I would expect after using 5 generations of Line 6 modelers over the past 20 years.

I suggested to try the stereo blocks by which I meant: try the blocks in the stereo fx category. That doesn't mean that every one of those blocks works for what you want:  Stereo (two channels that define a stereo field) isn't necessarily dual mono (two independent channels), but dual mono is always usable for stereo.

My point was that it is expected that if you use mono blocks the inputs L and R will be mixed.

On 7/12/2026 at 6:40 PM, ZiggyZipgun said:

They're less common now, but there were bi-amping bass combos that had a crossover built in, and that's easy to emulate with one input.  And a number of famous custom rigs sent different pickups to different amps, and that's easy to do with the Y-split.  Now I know these can be combined, even if it is definitely an edge case scenario.  It does have a unique benefit of being able to really combine two different pickup sounds into one, rather than layering, and it works equally well on my fretless P-bass with a mudbucker in the neck, my Jaguar tuned from A to A in all 5ths, and my Tele-ish Godin Session Custom tuned down to C# standard.  I've been using the Y-split for a few years, and it's pretty sweet to be able to save my pickup selection in each patch, flip the phase of a pickup with a footswitch, or switch from the neck to the bridge with an expression pedal.

Notice that this is the first time in the thread that you specified your use case in enough detail so that people can understand your point. Basically the limiting factor for you is that you're not being able to split twice - which tells me you're probably an HX Stomp (you didn't specify that either). 

 

Btw: For mixing your pickup signals as a Y-Split alternative (not Crossover Split) you can use the Volume/Pan(Stereo)->Pan block from the (or Stereo Width block if you want to be able to flip the phase). A mono block after it collapses it to one mono signal if needed.

[datacommando]

On 7/12/2026 at 5:40 PM, ZiggyZipgun said:

The Helix Floor and LT have aux inputs, but the impedance matching is not applied to that aux input.

Correct, the AUX input is a 10k ohm socket, but the Return jack sockets are selectable between Instrument or Line impedance, plus there are more of them on a Helix floor.

 

Hope this helps/makes sense.

[ZiggyZipgun]

On 7/12/2026 at 11:42 AM, Schmalle said:

Notice that this is the first time in the thread that you specified your use case in enough detail so that people can understand your point. Basically the limiting factor for you is that you're not being able to split twice - which tells me you're probably an HX Stomp (you didn't specify that either). 

That's just a couple of the ways that I use it, and I'm not trying to do those things simultaneously or split it twice.  But thanks for your original suggestion!