Headphone stereo routing

If I connect my monitors to Out 1 and 2, I can dial in a stereo preset by splitting the signal etc.
But with my headphones, it seems that the two outs are just summed to mono and then fed to the headphones. That means that I need to add extra gain blocks and pan left and right to actually get a true stereo out.
Might be a user error, but I can’t find a way to tell my headphones “out 1 is left, out 2 is right” unless I pan through the grid, which is not a sensible workflow.
Any ideas?


I noticed the same issue.
In1 to line1 and 2 to out 1
In2 to line 3 and 4 to out 2
Is stereo in my audio interface but not in headphone out of the quad cortex.
Could be a user error but it seems more like an implementation error for headphones out.

I’d chime in and ask if it is possible to turn down the volume on the OUT1 & 2 but still have the headphones turned up. If not, I have to turn the speaker cabs down manually or off entirely if I want to use the headphones without the speakers. So, said another way, am I correct that the headphones can only be used when the ‘mains’ are turned up, too?

OK it’s been a while since my original post, so I’ll answer both:

Regarding headphones and stereo:
Each output is by itself stereo. So while it’s true that by connecting two speakers to outs 1+2 or 3+4 you can create a stereo preset using two lanes (each sent to a different out), still each lane sends a stereo signal.
You can try the following tests to see what I mean:

Test 1: Create an empty preset with nothing but a Utility → Gain block. Route it to Out 1/2 (or 3/4), and play with the pan. You will hear the effect. Now route it only to out 1 (or 3), and again play with the pan. You will hear that instead of having maximum signal when it’s 50L and no signal when it’s 50R, you hear the signal at all times, but the volume is maximized when it’s centered and somewhat lower when it’s 50L/50R. This is because the left speaker receives the full stereo signal.

Test 2: Create an empty preset with a Digital Delay (ST). Turn the Ping Pong on, and route it to out 1/2 (or 3/4). Hit a note and you will hear the ping pong effect. Now route it only to out 1 (or 3). You will now only hear the left speaker playing, but the delay will repeat at the same rate both when the ping pong is on and off - the ping pong jumps left and right, but the left speaker receives both and plays both.

In conclusion - if you want stereo, you need to make an actual stereophonic preset, otherwise whatever you route to the headphones will be a sum to mono of the two stereo signals, rather than a sum of two mono signals sent respectively to the left and right channels of the headphone out.

You can certainly use the headphones independently of outs 1/2 and 3/4. They’re completely independent.
What you see in the I/O menu when you press the headphone out is basically a mixer: the HP LEVEL is the “master volume”, and all the others are how much each lane is fed to the headphone out.
For example, if lane 1 is set to Out 1/2 and lane 2 to Out 3/4, both will appear in the menu, and if you attenuate them, it will only affect their volume through the headphones - the speakers or whatever’s connected to these outs will be completely unaffected.

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That is all excellent information, thank you! Regarding Out 1/2, are you also implying that if I put an “insert cable” into, say, Output 1, that I’d get a Left and a Right signal on the send/receive portions of the cable, respectively? And if “yes,” can’t we also think of Output 1 or 2 as “Stereo-out 1” and 2? Or is your description of them as summed a better description? I guess another way to ask it, is, “are Output 1 & 2” TRS jacks because they are genuinely stereo, or because they are summed mono but also balanced… or are they summed stereo as mono-unbalanced (PS: regarding TRS or not, -that may be in the manual and I apologize I didn’t look there before asking the question.)

My understanding is :

  • Each QC ‘Lane’ (row 1,2,3,4) is able to ‘transport’ a stereo signal (let’s call them ‘parts’ , that is ‘Left Part’ and ‘Right Part’ of the signal)
  • So, internally, everything is processed as a stereo signal, some blocks can use both parts of the stereo image independently (like the Stereo Compressors), whereas other block will ‘sum’ the left and right part into a Mono signal (this is the case for Amp blocks, for example…)
  • Each Lane has one Input and one Output configuration.
    • The Input part can only select one input (Input 1 OR Input 2 OR USB 4 , etc…), it means that each input is Mono.
    • The Output part can either be a single Mono output (Output 1 , Output 3 , USB , etc…) OR can be a stereo output, like ‘Output 1 & 2’. (the ‘Multi-Out’ is simply a shortcut that allow us to send the stereo output to 1&2 + 3&4 + USB) .
    • So, if you send a stereo lane (say that this lane contains a Ping-Pong Delay) to a Mono output (say, Output 1) the QC will have to Sum the individual left and right parts into a single output, and you will ear the ‘Ping’ part on the same speaker as the ‘Pong’ part…
    • If the output of the lane is a Stereo one (say, Output 1 & 2), then each physical output will send a specific part of the stereo signal (so, physical Output 1 will carry the ‘Left’ part to your PA, and physical Output 2 the ‘Right’ part. This time, the ‘Ping’ part will be eard on one speaker, and the ‘Pong’ part on another speaker, producing a ‘true’ stereo delay).
  • Physically, each Input/Output port of the QC is a Mono port. It can only receive/send a Mono signal. Wereas you us a TS or TRS cable to transport that signal is up to you (I use a TRS cable because it is balanced and reduce noise, but still the signal is a mono one)

Neural DSP should provide more details about the whole process (and it would be really nice if they detailed the input/output capablilities of each block …) , even better if the ‘lane’ representation on the QC would visually show when the signal is ‘mono summed’ and where it is ‘true stereo’ , but I don’t think we will see this one day, the screen is too small to show those (rarely needed) infos … Perhaps that the Desktop Controller would be able to expose those additional informations ? It would be really nice, because the Desktop Controller would be more thant a simple ‘screen mirror’ of the QC …

(sorry for the long post :sweat_smile: )


Agree with everything you said, and much better worded than my post :slight_smile:

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Gosh, THANK YOU! I appreciate all the great communications in the QC community. Honestly, they are some of the best and most mature I’ve seen. Your post makes sense. I was just thinking this morning how helpful a technical reference manual would be for the QC; however, the time to make one would be better spent after rev 2.0 due to the massive changes coming, maybe even after 3.0! But I also would like to see some diagrams, or block-diagram images, of things like directory structures, menu stacks, and signal flow from connection and hardware architecture. I think all of that would be very helpful, too. However, coming from the software business as I do, I fully appreciate the labor required to do a good job of tech-ref materials. I would probably prefer to have the resources at Neural’ spend time on the amazing software release 2.0. Thank you again for your input!!

I appreciated both of your comments, and just want to take a moment and thank you for yours; it really helped! Have a GREAT week!


@flashtheproducer : you’re welcome ! thanks for your kind words.

Only Neural DSP has the full specifications, it would be great if they provide more insight on the more technical side stuff, but meanwhile we (the community) share our experience, and it enrich the whole community !

I’m pretty sure that my post is not 100% technically accurate, and I hope that if anyone has more accurate infos , (s)he would correct me so it would benefit to us all !

This afternoon, while playing with my QC , I noticed that I made a mistake saying :
" The Input part can only select one input (Input 1 OR Input 2 OR USB 4 , etc…), it means that each input is Mono."

In fact, on the ‘Input Select’ screen, we can select ‘Input 1 & 2’ for example… I don’t know if each input is summed as mono, or input 1 goes to the ‘Left’ part and Input 2 to the ‘Right’ part, but the second option would make sense, because when we use the ‘Split’ function, we have the possibility to separate the Left and Right part into 2 separate path …