Monitor mix output of Qu-16 into HM-800 very noisy

[FSchoenParticipant]

(I also posted this question to the sound stackexchange forum and will update both posts if I am able to resolve my problem)

I recently acquired an HM-800 in order to provide my fellow musicians with their own in-ear monitor mix, as my Qu-16 is capable of outputting four different mono mixes. Sadly I noticed that the output of the HM-800 is very noisy to the point of it being unusable for its intended purpose.

I created an image to better describe my situation. A1 is the output port of mix 1. A2 is the headphone monitor output of the mixer. M1 is the input of the HM-800 unit. Y1 is the input of an AG06 USB mixer which I used to check if the output of the Qu-16 itself is noisy:

I used a Cordial CFM 1,5 FV XLR 3-pol female to TRS male cable to initially connect A1 with M1, which resulted in a very noisy signal. I tried using a second cable of the same type with the same result. I then connected A1 to Y1 using the very same cable in order to check if the mixer itself produced noisy output. The resulting signal was completely fine, almost noiseless even. I then tried to connect the headphone output A2 to M1 using a Cordial CFM 1,5 VV TRS male to TRS male cable. This output was once again completely useable, but the mixer only provides a single TRS output.

I would like to ask for help regarding how to solve this issue. I note that I contacted Mackie support before as I suspected faulty product. I have since tested another unit with an entirely different serial number with the same result. Support stated that the mixer could be outputting at MIC level, when it should be outputting at LINE level, but I found no way of adjusting the output level of my mixes. If there is a way of adjusting the volume please tell me how to. Furthermore, the AG06 receives the exact same signal and is capable of producing a clean signal.

Could it be that I am using the wrong type of cable since the setup seems to work fine when connecting it to the headhpone output A2?

I am thankful for any kind of information as I am relatively inexperienced when it comes to audio routing!

[Mike CParticipant]

I just looked up the HM-800 headphone and as I kind of suspected the AUX inputs on that unit are STEREO TRS connections, that is why connecting those inputs to a balanced line out is not working.
That is also why connecting the HN-800 AUX input with a TRS cable to the QU16 headphone output did work.

You could make up some custom cables that jumper the tip and ring together and connect those to pin three of the xlr connector, the sleeve of the 1/4 plug would connect to pin 1 of the XLR that plugs into the mix outs.

The QU mix outs are all line level.
With the exception of the headphone jack the 1/4 inch outputs on the QU are all balanced line.

Good detail explaining your set up!!

[FSchoenParticipant]

Thanks so much for your answer!

Ideally, I would like to avoid having to solder my own cables, although if left with no other option I would still do it. But before that, if I understand you correctly I would need a cable that kind of “ignores” the second XLR pin, correct? In this case, would a XLR female to TS cable work? For example, this one?

Thanks again!

[Mike CParticipant]

The cable you linked to would not work, actually it would kind of work but you would
not have audio on the right channel of your headphones/IEMS through the HM-800 headphone amp.

The pin that would not need connected on the XLR is pin 3, the TRS plug is needed to get audio to both channels on the headphone amp.
To be honest Mackie using stereo inputs on the amp is kind of limiting and is almost always going need the use of some form of adapters to connect it to a system.

I don’t think the needed cable is going to be an off the shelf item, you may be able to modify the cables you have now.

[FSchoenParticipant]

Thanks for the input! I kind of figured out a solution in the meanwhile, through sheer luck:

I tested a few different cables and suddenly the output was very clear, even with the original cables. Properly plugging everything afterwards resulted in noisy output again though, which is why I tried to plug the cables only half way in, which seemed to completely resolve my issues. I suppose this acts in a similar way as modifying them in the way you described. Furthermore, since the Mackie allows for setting an input to mono I don’t have issues with only one channel of my IEMs being fed.

It may not be a very clean solution but it works perfectly fine! Thanks again for your input!

[Mike CParticipant]

Plugging the TRS plug in to the first click (about halfway ish) connects the tip
of the plug to the ring contact in the jack that gets you by the issues of a balance
line source connecting to stereo input.
Since the HM-800 has a mono mode you still get audio in both sides of the IEM’s

Good accidental fix/work around.

[Author]

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