Loud Hiss From Auxes

[Bonecat]

Finally got a chance to use my new CQ20B with my band at rehearsal last night. Everything seemed to go well except for our IEMs.

In our practice studio we use a wired IEM setup that runs in mono. Each aux output is connected to a 6 channel headphone amplifier with a balanced female XLR to 1/4” TRS patch cable. Extension cables then run to each band member. Each headphone amp channel is set to mono.

Everyone got CQ4You up and running. Each of us heard a loud hiss in our ears. Tweaking connections made no difference and the volume of the hiss changed with changes in the channel volume at the headphone amp. Two members also complained of low volume in their ears even though their channel volumes and mix volume were nearly pegged.

I’ve ordered new patch cables and a replacement headphone amp and I’m hoping the issue resides in one of those parts of the signal chain.

Has anyone else noticed this kind of noise issue in CQ outputs?

[Mike C]

What model is the headphone amp?
Some headphone amps are set up for a stereo input, the balanced output from the mixer
feeding a stereo input would cause issues, one of them very low level due to the phase cancellation.

[IdahoG]

I have a Furman HDS-6 that was sitting idle for 15+ years due to not being very practical for my jams. The CQ20 has breathed new life into it, making it very useful. Haven’t noticed low volume or hiss beyond what it normally has (the HR-6 mixing units connect to the HDS with ethernet cables and those give a slight hiss regardless of the CQ). You should connect the outputs from the CQ to something else like an amp to see if it still is hissy.

[Bonecat]

Thanks for the responses. I think I’ve figured it out.

First, I connected the cables for our studio speakers to a couple of the auxes – no hiss, quiet at idle and at full volume with all inputs muted. So it’s not the CQ.

Next, I started evaluating each link in the signal chain. We were using a 3’ long 8 element snake cable to connect the auxes to the Behringer HA8000 headphone amp. I’ve now identified multiple faults in the cable itself, including several breaks in the shielding. I cut the REAN connectors off that cable and pitched it. New cables have been ordered. I also noted that several of the output jacks on the amp were loose or intermittently working. I bought it used nearly 10 years ago and while I can probably repair it, I don’t want to have to rely on it. So, I ordered a somewhat nicer Mackie headphone amp that has similar features but appears to be more rugged.

The cables are supposed to be here tomorrow and I’ll be able to verify that everything is correct.

[Mike C]

What inputs are you using on the HA8000?
I’m almost certain all of the direct channel inputs are 1/4 inch TRS STEREO not balanced, feeding a balanced line signal to those inputs would cause issues.
The Mackie would be the same way, Behringer copied the Mackie.

If your using the main stereo inputs then you would connect an aux send to the left and another aux send to the right.

[Mike C]

Ok I just looked up the manuals for the HA8000 and the HM800.
The direct input description seems to be mono the way it’s worded, some other places
in the manual the wording is not quite so clear!

A friend of mine had one of the Behringers and I remember some issue with it.

Let us know.

[Evorgeloc]

Please forgive what is probably a naive question… why the headphone amp? Why not an aux out to wired headphone controlled by CQ4U?

[Mike C]

Please forgive what is probably a naive question… why the headphone amp? Why not an aux out to wired headphone controlled by CQ4U?

The direct aux outs are mono balanced line outputs and not for driving headphones or IEM’s. A headphone amp will drive stereo headphones from a stereo input sources. Most mixers require two aux outs for stereo mix operation, at the headphone amp or IEM transmitter is where those left right sources are brought together to one common stereo signal.
Also headphone amps are better suited for driving lower impedance loads.

[Evorgeloc]

👍Thank you Mike C 🙏

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