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Mixer combo jack TRS inputs vs line inputs

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Mixer combo jack TRS inputs vs line inputs

Postby danlouis » Tue Jul 30, 2019 11:48 pm

Hi there, newbie here

I've just got a Behringer XR12 digital mixer, and I want to run one of its aux outs through a couple of effects pedals and then back into one of the mixer inputs, ala an external FX loop. The signal going back into the mixer will be a low-ish line level (which is what the pedals can tolerate). The mixer has both combo XLR/TRS jacks sockets and normal 1/4" TRS line in sockets on the front, and I'm basically wondering which type of socket is better to return the effects through?

I emailed Behringer and their response claimed that the TRS part of the combo jacks are processed just the same as the 1/4" line inputs, but that isn't what the (digital) mixing console seems to suggest - with a 1/4" jack plugged in a combo input, that input's gain controls are the same as when an XLR is inserted, and differ from the normal 1/4" line input controls (much higher maximum gain for the combo socket for example). Given how robust mic preamps are these days, is it possible that the TRS part of the combo jack actually goes through the corresponding mic preamp, unlike a normal line input socket? If so, would this mean that for a low-ish signal level, the combo jacks will be a better option, with the mic pres more suited to taking fairly low signals?

Cheers, Dan :)
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Re: Mixer combo jack TRS inputs vs line inputs

Postby Hugh Robjohns » Wed Jul 31, 2019 12:17 am

Welcome to the SOS forums, Dan!

danlouis wrote:I'm basically wondering which type of socket is better to return the effects through?

Whichever is most convenient and/or provides sufficient gain.

...TRS part of the combo jacks are processed just the same as the 1/4" line inputs...

I think some misunderstanding has crept in that Behringer statement somewhere. The combo-TRS is padded down and routed through the mic preamp, so has the full mic pre gain range available. The separate line inputs have a different preamp design with a Trim control which offers a far smaller gain range. ... Exactly as you have said.

...is it possible that the TRS part of the combo jack actually goes through the corresponding mic preamp...

Yes, absolutely. It's a pretty common practice in most consoles and interfaces.

If so, would this mean that for a low-ish signal level, the combo jacks will be a better option, with the mic pres more suited to taking fairly low signals?

Potentially, yes. You'll certainly be able to cope with much lower signal levels via the combo-TRS inputs. But you may well find that the standard line inputs have enough range on their trim controls to cope with the output of FX pedals too. I'd give it a go and see if there's enough gain to work in your application.
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Re: Mixer combo jack TRS inputs vs line inputs

Postby Sam Spoons » Wed Jul 31, 2019 9:21 am

I have an XR12 (and a couple of X32s) and the 'line inputs' have enough gain to handle guitars straight in so should have more than enough to handle a return from a guitar pedal.

I think what Berry may mean by 'the same processing' is that the line channels have the same features as the mic channels (this is not the case with the X32's 'aux' input channel strips which have a reduced feature set).
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Re: Mixer combo jack TRS inputs vs line inputs

Postby AlecSp » Wed Jul 31, 2019 9:37 am

Hugh Robjohns wrote:I'd give it a go and see if there's enough gain to work in your application.
Almost certainly, either would work. Try both and see if you can tell the difference - you'll have learnt something along the way.

And this is the first time I think I've come across anyone wanting to patch outboard into their XR mixer!
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Re: Mixer combo jack TRS inputs vs line inputs

Postby The Elf » Wed Jul 31, 2019 9:58 am

AlecSp wrote:...this is the first time I think I've come across anyone wanting to patch outboard into their XR mixer!
+1 Seems a bit like wanting to pull a caravan with an Aston Martin! There are sooooo many good effects in the XR that I can't imagine needing to go outboard for more!
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Re: Mixer combo jack TRS inputs vs line inputs

Postby Arpangel » Wed Jul 31, 2019 10:54 am

The Elf wrote:
AlecSp wrote:...this is the first time I think I've come across anyone wanting to patch outboard into their XR mixer!
+1 Seems a bit like wanting to pull a caravan with an Aston Martin! There are sooooo many good effects in the XR that I can't imagine needing to go outboard for more!

But has it got a Ring Thing or a Thermae built in?

:D :D
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Re: Mixer combo jack TRS inputs vs line inputs

Postby AlecSp » Wed Jul 31, 2019 4:41 pm

The Elf wrote:
AlecSp wrote:...this is the first time I think I've come across anyone wanting to patch outboard into their XR mixer!
+1 Seems a bit like wanting to pull a caravan with an Aston Martin! There are sooooo many good effects in the XR that I can't imagine needing to go outboard for more!
To be fair, there's a whole load of performance style where I could see wierd & whacky pedals, with their immediacy of controls adding to the whole show, especially when operated by the performer.

But it's certainly not standard production!

The good thing is that, with a tiny bit of planning, as Dan is doing here, the mixer can easily support what he wants to do.
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Re: Mixer combo jack TRS inputs vs line inputs

Postby danlouis » Wed Jul 31, 2019 8:58 pm

Thanks for the replies guys! I'll try both kinds of inputs and see if I can hear a difference, but it's good to know both should probably work reasonably well.

I know what I'm doing is a bit unorthodox but the reason is that the main reason I've got an XR12 is to blend 3 different acoustic guitar pickups together, with the ability to EQ them separately etc, which is hard to do without some kind of digital mixer. That's why it's becoming a bit of 'a thing' to do it this way for certain kinds of guitar music. So the mixer's really just part of my pedal board, and the other effects are things like whackier reverbs etc that I want to be able to switch easily with my feet. Also an octave pedal, because the one in the XR12 doesn't seem to be polyphonic unfortunately (did not like chords at all!). So that's the motivation for the weird setup, but as someone said, the mixer seems well up to the job, and is way smaller and lighter than the pile of stuff I had to carry before!

Cheers, Dan :)
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Re: Mixer combo jack TRS inputs vs line inputs

Postby The Elf » Wed Jul 31, 2019 11:01 pm

Thanks for sharing this. It's always interesting to hear how people bend gear to their needs. I frequently get raised eyebrows when I turn up to gigs with guitar pedalboards under my keyboards!
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Re: Mixer combo jack TRS inputs vs line inputs

Postby Sam Spoons » Wed Jul 31, 2019 11:19 pm

And some audio examples of what you are doing would be welcome as I am now officially intrigued :D
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