# Qu-5 Main outs and Headphones hearing input ST1 (L & R) no matter what **URL:** \ **Category:** Qu Troubleshooting\ **Created:** [30 September 2026 00:00 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047 "2026-09-30T00:00:56Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![IzenEars](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@IzenEars](https://forums.allen-heath.com/u/IzenEars)\ **Post date:** [30 September 2026 00:00 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/1 "2026-09-30T00:00:56Z")
I have all inputs muted and faders down, but from the main out and the headphones I hear what sounds like a PAFL of that one channel. But no PAFLs are engaged. It does not come out of the mixes, only the mains and headphones. The level remains the same no matter what I gain it up to. When I unmute and turn up the fader, it gets louder. I swapped to the ST2 input and it’s totally normal, no sound unless I raise the fader. Is this a firmware thing or is my ST1L input just riddled with crosstalk or something? ---
**Author:** ![mikec](https://avatars.discourse-cdn.com/v4/letter/m/977dab/32.png) [@mikec](https://forums.allen-heath.com/u/mikec)\ **Post date:** [30 September 2026 14:00 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/2 "2026-09-30T14:00:48Z")
I assume the main output fader is muted. Maybe an effects mix routing? Have you tried a hard reset? What is the firmware version? ---
**Author:** ![IzenEars](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@IzenEars](https://forums.allen-heath.com/u/IzenEars)\ **Post date:** [30 September 2026 15:29 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/3 "2026-09-30T15:29:05Z")
Hello! Thanks for the reply. It’s not the board, because when I switch scenes the issue goes away. Whew. So I just rebuilt the scene. NOW I really want to know what the problem was in case it happens again. Nothing is muted, but when I mute the main mix it disappears. In fact - that ST1 input (both L & R), is always in the main mix no matter what. Check out the photo (I swapped faders for 17/18 for 19/20 because of this issue). You can see Ip17 & Ip18 are getting the signal. The faders are both down, and yet the main mix is sending the signal through, I changed the input routing for Ip17 & Ip18 to be Ip16, so now the Ip faders show nothing incoming - but the ST1 is still in the main mix. I went to routing / main and switched the “mainLR” to off, that did nothing. This also did nothing with ST2, which is the channel that does work normally. I have no idea what those MainLR on/off buttons are supposed to do. I turned off all the FX and matrices. It doesn’t do it with ST2. I am completely stumped. Firmware 1\_1\_3\_r3931 (I just updated from 1.1.2r3917). No change after updating. ![IMG_1447](https://us1.discourse-cdn.com/flex002/uploads/allenheathdigitalcommunity/original/2X/2/20b5ef34b01736cb102892089c730a91d21c61a5.jpeg) ---
**Author:** ![SQuser](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.allen-heath.com/squser/32/1200_2.png) [@SQuser](https://forums.allen-heath.com/u/SQuser)\ **Post date:** [30 September 2026 19:28 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/4 "2026-09-30T19:28:58Z")
As previously recommended, it is always best in situations like this to consider resetting the console to confirm that the issue is essentially user-induced rather than a technical fault. Although you have patched the two ST1-inputs to two input channels, to the best of my knowledge, they are also still hard-wired to the default ST1 input channel on the QU-2.0. Check that channel (which might not even be assigned to a layer) to see if it is actually muted. And by the way: > [@IzenEars](#): > > The level remains the same no matter what I gain it up to. … ST channels do not have gain controls. They only have trim controls in the respective input channels. ---
**Author:** ![IzenEars](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@IzenEars](https://forums.allen-heath.com/u/IzenEars)\ **Post date:** [30 September 2026 20:10 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/5 "2026-09-30T20:10:07Z")
I’m not sure what you mean because the gain / trim knob definitely affect ST1 and ST2’s input levels. They do have gain, and when I turn it up and down I see the input level changing. So I really don’t understand this comment. I brought it up to point out that whatever gain I set does not affect what’s going to the MAINLR. I don’t get it. Ip17 was not muted. No inputs are muted, but the faders are down. I did mute every channel just to see, but it didn’t make a difference. I did a reset and nothing changed, but when I switched scenes, it became normal. So I rebuilt the scene and I’m good FOR NOW - but what if it happens again? I don’t understand what you mean with “patched the two ST1-inputs to two input channels” - I must have been unclear. I did not change the i/o of the ST1 inputs, they’re still 17 & 18. (ST2 is 219 & 20.) Perhaps I was talking about when I switched Ip17 and Ip18 to Ip16, but I switched it back, When you said ST1 is hardwired to its default channel - that’s Ip17 & Ip18. So it’s still a complete mystery. I REALLY want to know what happened. I cannot find any difference in the settings between the old scene and the new one, except that ST1 goes through the mains no matter what. ---
**Author:** ![SQuser](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.allen-heath.com/squser/32/1200_2.png) [@SQuser](https://forums.allen-heath.com/u/SQuser)\ **Post date:** [30 September 2026 20:34 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/6 "2026-09-30T20:34:08Z")
> [@IzenEars](#): > > the gain / trim knob definitely affect ST1 and ST2’s input levels. I wrote that the ST inputs don’t have a gain control, but rather just the trim control, which is present in the input channel anyway (see block diagram). ![quga](https://us1.discourse-cdn.com/flex002/uploads/allenheathdigitalcommunity/original/2X/b/b252621e96f295cec00f80fbf384fc42d95ef979.jpeg) > [@IzenEars](#): > > I did not change the i/o of the ST1 inputs, they’re still 17 & 18. Ah, now I see - that’s because I don’t own a QU myself to verify this firsthand. On the QU-5, the ST inputs are likely additional patched starting at channel 17 by default (since they would otherwise be empty), whereas on the QU-6, channel 17 ist the local input 17. Regardless, the 3 stereo channels ST1, ST2, and USB should do exist. And if ST1 isn’t muted and the fader isn’t closed, that - at least from my perspective - would explain the problem you’re having. ---
**Author:** ![SQuser](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.allen-heath.com/squser/32/1200_2.png) [@SQuser](https://forums.allen-heath.com/u/SQuser)\ **Post date:** [30 September 2026 21:11 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/7 "2026-09-30T21:11:12Z")
> [@SQuser](#): > > Regardless, the 3 stereo channels ST1, ST2, and USB should do exist. ![qugb](https://us1.discourse-cdn.com/flex002/uploads/allenheathdigitalcommunity/original/2X/d/df00528d9b3a443089defc9f90c1195d6c231e63.jpeg) ---
**Author:** ![IzenEars](https://avatars.discourse-cdn.com/v4/letter/i/9de0a6/32.png) [@IzenEars](https://forums.allen-heath.com/u/IzenEars)\ **Post date:** [1 October 2026 00:35 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/8 "2026-10-01T00:35:41Z")
Thank you. Right, it’s a trim control on the SRT1 and ST2 inputs, but nevertheless, adjusting it moved the input level up and down. What’s relevant is that I hear ST1 no matter what position that knob is at - and the level going to the mains does not change with the knob. It’s as if the mains are hearing the prefade of that channel, except it’s also pre-trim! But, there is no way to get a pre-fade input on the main mix. At least not that I found. Yes the fader for Ip17 is completely down (“closed” if you will), and muting does nothing to stop the sound coming out of the mains. However, if I unmute and raise the fader, the sound gets louder. If you have any other ideas, please share! I really need to know what happened. ---
**Author:** ![SQuser](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.allen-heath.com/squser/32/1200_2.png) [@SQuser](https://forums.allen-heath.com/u/SQuser)\ **Post date:** [1 October 2026 06:20 UTC](https://forums.allen-heath.com/t/qu-5-main-outs-and-headphones-hearing-input-st1-l-r-no-matter-what/33047/9 "2026-10-01T06:20:49Z")
Please try to understand the basics of your console. Your console features not only 32 Mono input channels but also 3 Stereo input channels. ![qugc](https://us1.discourse-cdn.com/flex002/uploads/allenheathdigitalcommunity/original/2X/9/93939caea117f5041038b31fc96a55ecc7bc689a.jpeg) So, please disregard your mono input channels Ip17 and Ip18 for now - I speak about the stereo input channel ST1, which is also connected to your local ST1 jacks (labeled Ip33/34 in the image). And if this channel is not muted and its fader is not closed, the signal from the ST1 jacks will reach the Main LR - also if your Ip17 and Ip18 are muted. ![qugd](https://us1.discourse-cdn.com/flex002/uploads/allenheathdigitalcommunity/original/2X/e/eff19f9c203f7d6a8f366cca73b89902cf2947a8.jpeg) > [@IzenEars](#): > > it’s a trim control on the SRT1 and ST2 inputs, but nevertheless, adjusting it moved the input level up and down. What’s relevant is that I hear ST1 no matter what position that knob is at - and the level going to the mains does not change with the knob. Adjusting the trim controls for Ip17 and Ip18 does not affect the trim control for channel ST1 (Ip33/34). Consequently, the level of your unwanted audio signal remains constant.