The IEM (in ear monitors) Bible thread - a guide to help every musician

[Woodinblack]

Mine were labeled a few years ago, and since then we have had no issues. Apart from a couple of times when the bass drum has ended up in the bass socket.

[dave_bass5]

1 hour ago, Woodinblack said:

Mine were labeled a few years ago, and since then we have had no issues. Apart from a couple of times when the bass drum has ended up in the bass socket.

Yeah, things have got better, but these days some are more inclined to throw the cable over and expect our drummer to do it. He likes doing all that stuff and it takes the pressure of me. 

Edited yesterday at 14:21 by dave_bass5

[Al Krow]

6 hours ago, SimonK said:

 

Ha - yes - I thought this was a given that you can't just plug headphones into something without a headphone preamp. I can't understand why anyone would try to plug headphones into an aux out!

 

I guess because it just works? Flawlessly. For the 70+ gigs that we've used the A&H CQ18T desk since getting it. At each gig we've had one or two band members using a wired IEM straight into the aux outs (with no separate external headphone amp), and with the desk output levels being set for them no higher than for the wireless IEMs.

 

Just to make sure I'm not losing the plot, I've just tried the desk with my home over-ear headphones and no external headphone amp. Could very clearly hear recorded output at similar volumes for both the headphone-out and aux-out with similar output levels on both.

 

Go figure 😅

Edited yesterday at 16:32 by Al Krow

[SimonK]

1 hour ago, Al Krow said:

 

I guess because it just works? Flawlessly. For the 70+ gigs that we've used the A&H CQ18T desk since getting it. At each gig we've had one or two band members using a wired IEM straight into the aux outs (with no separate external headphone amp), and with the desk output levels being set for them no higher than for the wireless IEMs.

 

Just to make sure I'm not losing the plot, I've just tried the desk with my home over-ear headphones and no external headphone amp. Could very clearly hear recorded output at similar volumes for both the headphone-out and aux-out with similar output levels on both.

 

Go figure 😅

 

Must be something about that particular desk if headphones work directly because aux outs produce line level which is the standard for routing between different bits of gear (e.g. in a rack) whereas headphone level is a lot higher. There are a few caveats (-10dBV vs +4 dBu variants) but the wikipedia article explains it well: https://en.wikipedia.org/wiki/Line_level

 

EDIT - in thinking about this I bet the manufacturers are targetting these small desks towards home studio users and thus build something like this in as a feature so people don't have to buy additional headphone amps. Thus said it makes me a bit scared as high headphone levels running into expensive rack gear has the potential to break things! I probably wouldn't buy this specific mixer if it was indeed doing this.

 

EDIT2 - just downloaded and read the manual because I couldn't quite believe designers would do this, and the aux level is +4 dBu as expected, although the desk does seem to have two separate headphone outs that can monitor the aux mixes so I suspect these are what the IEMs connect to.

Edited yesterday at 17:21 by SimonK

[Al Krow]

20 hours ago, SimonK said:

 

Must be something about that particular desk if headphones work directly because aux outs produce line level which is the standard for routing between different bits of gear (e.g. in a rack) whereas headphone level is a lot higher. There are a few caveats (-10dBV vs +4 dBu variants) but the wikipedia article explains it well: https://en.wikipedia.org/wiki/Line_level

 

EDIT - in thinking about this I bet the manufacturers are targetting these small desks towards home studio users and thus build something like this in as a feature so people don't have to buy additional headphone amps. Thus said it makes me a bit scared as high headphone levels running into expensive rack gear has the potential to break things! I probably wouldn't buy this specific mixer if it was indeed doing this.

 

EDIT2 - just downloaded and read the manual because I couldn't quite believe designers would do this, and the aux level is +4 dBu as expected, although the desk does seem to have some "alt outs" that are assignable so perhaps these can give higher levels.

 

Kudos to you for taking the trouble to read the the A&H desk manual.

 

Only additional comments from me are that:

 

- this desk is very much geared to live gigging bands (they wouldn't have bothered with super nice touches like real time feedback elimination assistance otherwise, I suspect?)

 

- and that A&H are a very reputable manufacturer, who aren't particularly associated with cutting corners.

Edited 6 hours ago by Al Krow

[TimR]

Page 69.

 

Alt Out (CQ-20B)

The Alt Out provides an alternative balanced TRS output connection. Source – Select any other Output or route the Listen out.

 If Listen is set, when no Listen button is pressed, the Alt Out will be sourced from Main LR.

 Listen is sent to the Alt Out at full volume for use with IEM systems that have input level control. For adjustable level, the headphone output should be used. 

[dave_bass5]

And this  is why i said ‘most desks’ in my first post about this. Ive had maybe 20+ desks over time and not one would allow headphones to be plugged in to a send jack and get a decent level. 

[Woodinblack]

1 hour ago, dave_bass5 said:

And this  is why i said ‘most desks’ in my first post about this. Ive had maybe 20+ desks over time and not one would allow headphones to be plugged in to a send jack and get a decent level. 

 

Agreed - but it would have never occured to me to actually plug a headphone in there. In fact if someone had tried that with one of my mixers they would have had a good kicking!

[Woodinblack]

6 hours ago, Wombat said:

I’ve labled everything but one of the guitarists ‘needs his glasses’ so still dosent plug in the right holes 😂

 

Different colour label to the rest!

[Wombat]

Good idea but his mic is in 1, so the left most input. The first input. The one the furthest from the Red fader. The same f&#@in one it is EVERY time.

And he still doesn’t get it 😂.

[dave_bass5]

5 minutes ago, Woodinblack said:

 

Agreed - but it would have never occured to me to actually plug a headphone in there. In fact if someone had tried that with one of my mixers they would have had a good kicking!

I have, or worked with others that have tried. It's never been ideal. 

[Al Krow]

15 hours ago, Woodinblack said:

 

Agreed - but it would have never occured to me to actually plug a headphone in there. In fact if someone had tried that with one of my mixers they would have had a good kicking!

 

I was a little worried from the some of the comments above that plugging a headphone into a line-level aux-out could somehow cause damage to the desk circuitry. But seems from my online research I can rest easy on that score, as the only issue is likely to be insufficient volume in the IEM ear pieces if the signal has not been subsequently amplified? (Which, as noted above, doesn't seem to be a concern with the A&H CQ desks).

[TimR]

54 minutes ago, Al Krow said:

 

I was a little worried from the some of the comments above that plugging a headphone into a line-level aux-out could somehow cause damage to the desk circuitry. But seems from my online research I can rest easy on that score, as the only issue is likely to be insufficient volume in the IEM ear pieces if the signal has not been subsequently amplified? (Which, as noted above, doesn't seem to be a concern with the A&H CQ desks).

 

To enable the headphones over AUX it looks like you have to select 'listen' for that particular AUX out. So doesn't look like something that would be done accidentally.

 

And I've never seen a line level input 'blown' by putting headphone level output into it. You just get an awful lot of distortion. So even if you did have something connected to that AUX and selected Listen, it would be unlikely to do any damage. 

 

Consumer electronics are very robust. 

[Woodinblack]

1 hour ago, Al Krow said:

I was a little worried from the some of the comments above that plugging a headphone into a line-level aux-out could somehow cause damage to the desk circuitry. But seems from my online research I can rest easy on that score, as the only issue is likely to be insufficient volume in the IEM ear pieces if the signal has not been subsequently amplified?

 

Yes, I am very surprised it works, and I can only assume that A&H realised that people plug headphones into their mixers, so they decided to detect that and boost the output. I would expect that there is little risk of damage to any pro audio equipment because the companies would expect things to be done wrong, and also when you have an signal output it is designed to be laid over a stage and may sometimes get damaged and shorted, and that has to not break the amplifiers so there should always be be protection against that kind of use.

[Woodinblack]

Also one of the reasons I wouldn't want that (regardless of being wireless, but if I wasn't), I need a real physical volume knob for partually to adjust as I go along, but mainly because at some point towards the end of the gig, our singer will somehow select the most tone deaf and loud woman in the audience to screech into the microphone with him, and I need to be able to kill that instantly!

[Al Krow]

30 minutes ago, Woodinblack said:

Also one of the reasons I wouldn't want that (regardless of being wireless, but if I wasn't), I need a real physical volume knob for partually to adjust as I go along, but mainly because at some point towards the end of the gig, our singer will somehow select the most tone deaf and loud woman in the audience to screech into the microphone with him, and I need to be able to kill that instantly!

 

I appreciate you have somewhat unusual and sometimes challenging circumstances to deal with Woody 😅

[Al Krow]

1 hour ago, TimR said:

 

To enable the headphones over AUX it looks like you have to select 'listen' for that particular AUX out. So doesn't look like something that would be done accidentally.

 

And I've never seen a line level input 'blown' by putting headphone level output into it. You just get an awful lot of distortion. So even if you did have something connected to that AUX and selected Listen, it would be unlikely to do any damage. 

 

Consumer electronics are very robust. 

 

Tim - that's super helpful, thanks. I'll need to go back and check what settings we currently have for the aux-outs and what difference it's making. I can then make sure we have dedicated wireless (with transmitter amps) and wired (no external amps) aux-outs, if required, or simply leave as is if it's just a case of the "select listen" option impacting the inherent desk output levels for the IEMs, given none of our existing output levels are close to being maxed.

 

But it seems to me that this provides a "best-of-both worlds" option, avoiding unnecessary expenditure on external IEM amps for wired IEMs, which is an unexpected additional cap-feather in it's already significant haul for the CQ range. Bravo A&H!

 

Edited 7 hours ago by Al Krow

[Phil Starr]

There is no mystery about headphones and line outputs. Just looking at the Sennheiser IEM100 because that's waht I have to hand they are a 20ohm load and produce 115db for a 1V rms output or 0dbV. Line level is usually quoted as 0.7746V into 600ohms. In practice the output is often fine up to +10dbu and almost always +4dbu or 1.228V rms. 

 

So whilst there may be an impedance mis match (leading to a lack of current) a line output from most mixers will go well above 1V and deliver 115db right in your ears, plenty enough to cause you permanent tinnitus and with a good seal  able to hear yourself. The headphone amp just gives you a better impedance match between mixer and phones, with a bit of extra gain with and a volume control.

 

Correction: I was just musing about how levels here. I don't think this is a practical or sensible way to go when headphone amps are so cheap. Please don't do this at a gig and read my next post

Edited 2 hours ago by Phil Starr

[Al Krow]

24 minutes ago, Phil Starr said:

There is no mystery about headphones and line outputs. Just looking at the Sennheiser IEM100 because that's waht I have to hand they are a 20ohm load and produce 115db for a 1V rms output or 0dbV. Line level is usually quoted as 0.7746V into 600ohms. In practice the output is often fine up to +10dbu and almost always +4dbu or 1.228V rms. 

 

So whilst there may be an impedance mis match (leading to a lack of current) a line output from most mixers will go well above 1V and deliver 115db right in your ears, plenty enough to cause you permanent tinnitus and with a good seal  able to hear yourself. The headphone amp just gives you a better impedance match between mixer and phones, with a bit of extra gain with and a volume control.

 

Thanks Phil, helpful as always!

 

But, if what you say is correct (and I don't doubt that it is for a second!), that's making me think that the various earlier comments of: "you should never put an IEM cable into a line-level aux-out, without a headphone amp" as being an over-cautious old wives tale?

[Woodinblack]

27 minutes ago, Al Krow said:

But, if what you say is correct (and I don't doubt that it is for a second!), that's making me think that the various earlier comments of: "you should never put an IEM cable into a line-level aux-out, without a headphone amp" as being an over-cautious old wives tale?

 

Well, one thing, if it is not designed for it, if (for instance) I plugged some headphones into the TRS aux output of the X18 ihave, and it could drive it (and I have never tried, so can't say for definite), the ears would be inverted from each other - the tip and ring of a TRS aux are the positive and negative of the output, and the ground is just the cable ground. Headphones are tip to ground and ring to ground per ear, so in headphones when your left ear was pushing, your right ear would be pulling and viceversa.

But irrelevant if the QC18 is designed to also run a headphone, I assume it fixes that.

[Al Krow]

2 hours ago, Woodinblack said:

 

Well, one thing, if it is not designed for it, if (for instance) I plugged some headphones into the TRS aux output of the X18 ihave, and it could drive it (and I have never tried, so can't say for definite), the ears would be inverted from each other - the tip and ring of a TRS aux are the positive and negative of the output, and the ground is just the cable ground. Headphones are tip to ground and ring to ground per ear, so in headphones when your left ear was pushing, your right ear would be pulling and viceversa.

But irrelevant if the QC18 is designed to also run a headphone, I assume it fixes that.

 

Thanks Woody. But that's an additional point to amplification though? And would on the face of it apply to any IEM whether wired or wireless being fed into an aux-out?

 

I see that the 6 aux-outs of the Beheringer XAir XR18 are all 3 pin XLR  - so no possibility of putting a normal headphone jack into those sockets, plus one headphone out?

The aux out sockets on the CQ18 are balanced mono, and I remember you saying that most aux outs are similarly mono? Now the Xvive U4s we used are also mono - so I guess that deals with any phasing issues for those particular devices?

 

But given what you're saying, that then leaves the question as to why we or anyone gets a clear feed into stereo IEM headphones where the balanced mono of an aux output is being matched with an unbalanced stereo jack?

 

Edited 2 hours ago by Al Krow

[Phil Starr]

3 hours ago, Al Krow said:

 

Thanks Phil, helpful as always!

 

But, if what you say is correct (and I don't doubt that it is for a second!), that's making me think that the various earlier comments of: "you should never put an IEM cable into a line-level aux-out, without a headphone amp" as being an over-cautious old wives tale?

I possibly didn't think this one through did I? Just because you can do something doesn't mean you should.

 

So could you drive headphones with the line output from a mixer? Well yes, what I didn't say was if I thought it was a good idea and the answer is probably not, most of the time. The outputs are almost always balanced mono so you'd need to wire a connector specifically to take that to your headphones and drive both sides. Secondly not all headphones have the same impedance so the mis-match may be serious enoughthat you'd lose a lot of output. I'd be checking the manual before starting this. If a new lead is going to cost you £10 then you are well on the way to a simple beltpack headphone amp. The Behringer P2 is £23. Ali Express are doing one for £13 that looks very like The Behringer and a passive one for <£10 I'm not really sure why you wouldn't go that route. 

 

As you were

[dave_bass5]

4 hours ago, Al Krow said:

 

Thanks Phil, helpful as always!

 

But, if what you say is correct (and I don't doubt that it is for a second!), that's making me think that the various earlier comments of: "you should never put an IEM cable into a line-level aux-out, without a headphone amp" as being an over-cautious old wives tale?

How would you adjust the volume from the other side of the stage or away from the mixer?

Edited 1 hour ago by dave_bass5

[Woodinblack]

1 hour ago, Al Krow said:

Thanks Woody. But that's an additional point to amplification though? And would on the face of it apply to any IEM whether wired or wireless being fed into an aux-out?

 

Absolutely not. If you connect to a TRS you have a balanced output, and a ground. The signal (a mono one) is amplified in some IEM amplifier, the ground maybe connected to the hardware ground, or isn't, it doesn't matter. that is the correct way. If you connect a mono source to a stereo output, you need to sum both stereo lines to that mono line. The way you are doing if you are putting a mono source into a stereo headphone, both sides are 180 degrees out of phase with each other.

 

 

1 hour ago, Al Krow said:

I see that the 6 aux-outs of the Beheringer XAir XR18 are all 3 pin XLR  - so no possibility of putting a normal headphone jack into those sockets, plus one headphone out?

 

I have an X18, not an XR18, they are all TRS (and a headphone out). But they are aux line level out so it would have never occured to me to put them into a headphone! (and the normal aux I used was a TRS plug to an XLR socket.

 

1 hour ago, Al Krow said:

The aux out sockets on the CQ18 are balanced mono, and I remember you saying that most aux outs are similarly mono? Now the Xvive U4s we used are also mono - so I guess that deals with any phasing issues for those particular devices?

 

Absolutely. In fact any 'normal'* IEM system would expect a balanced mono, the same as most other XLR use in gigging 

 

 

1 hour ago, Al Krow said:

But given what you're saying, that then leaves the question as to why we or anyone gets a clear feed into stereo IEM headphones where the balanced mono of an aux output is being matched with an unbalanced stereo jack?

 

Maybe you don't notice the phase or there is that thing that people mentioned on the CQ settings that lets you set it as a headphone out (or maybe headphone stereo).

 

* the P2 has a stereo switch and allows you to use it as a stereo.

[Al Krow]

26 minutes ago, Phil Starr said:

I possibly didn't think this one through did I? Just because you can do something doesn't mean you should.

 

So could you drive headphones with the line output from a mixer? Well yes, what I didn't say was if I thought it was a good idea and the answer is probably not, most of the time. The outputs are almost always balanced mono so you'd need to wire a connector specifically to take that to your headphones and drive both sides. Secondly not all headphones have the same impedance so the mis-match may be serious enoughthat you'd lose a lot of output. I'd be checking the manual before starting this. If a new lead is going to cost you £10 then you are well on the way to a simple beltpack headphone amp. The Behringer P2 is £23. Ali Express are doing one for £13 that looks very like The Behringer and a passive one for <£10 I'm not really sure why you wouldn't go that route. 

 

As you were

 

Hmmm...

 

We've got balanced mono aux outputs as previously noted.

 

We've got and used a 1/4" TS to 3.5mm TRS adapter jacks (the lower silver jack in pic) to allow us to plug in to the desk to deal with the issues that Woody mentioned.

 

What stumps me though is why we're getting equally good results with 1/4" TRS to 3.5mm TRS stereo adapters (upper jack), with standard IEM headphones with standard 3.5mm TRS jacks?! So we're using either without issue.