Mixers/Consoles Wiring Mixer Aux-Send to Stage via XLR snake

[cjparsons74]

Hi, I'm sure this must have been answered before but I've searched without finding an answer.

Our church's mixer (Studiomaster trilogy 326) has four main aux ouput feeds, each channel can be mixed into any of the aux feeds, and the aux feed has a level control too. You know the score.

We use one of these aux feeds to supply a single mix of foldback where it goes into an active montitor speaker (which has a passive sibling also connected).

We have a multicore 'snake' running between stage and mixing desk. This is wired for XLR. Connections.

The aux feed from the desk has a jack socket connector.

Q1: I presume this is a mono Jack? There are no pan controls on the aux feeds, no spearate L/R knobs etc. Mono seems normal. Am I right?

To patch one of the snake channels into the desk somone has chopped off the XLR connector on the desk-end of the snake and soldered on a mono 1/'4 in jack plug.

I find that unless I waggle the wire & jack 'just right' I get major major hum through the foldback speakers. I don't know whether this is just the soldering job or whether there's something fundamentally awry. It might be the desk I guess, though all four aux send seem to behave similarly.

Q2: To connect the three-wire 'snake' channel to the mono 1/4 jack, I should connect Xlr-pin-2 to the tip and pin 1& 3 + any shield to the ring?

Q3: Is this what people would normally do in my situation? Or should I use a DI box or somthing to connect the aux send to the multicore?

Thanks in advance...

Chris

 

[Footer]

You need a TRS balanced 1/4" connector.

If you want to solder the XLR back on, you could make an adapter going from XLR to 1/4" but that is the long way around.

This guide will help you with how the soldering should be done. Soundcraft - [Support]

You are basically taking a balanced output and making it unbalanced by putting the ground and signal - together.

Any radio shack will have the right part, go grab it, solder it up... your problem should be solved.

 

[DaveySimps]

Hi Chris. My first guess is that it may be a bad solder job on the tip ring sleeve 1/4" jack. Certainly resoldering it would not hurt at all as long as whoever is doing the soldering knows how to do it. It certainly could be a number of other issues as well. Does the same output(s) hum when you hook them up to something else? It could also be a power issue with the active speakers or many other things. Yes, the aux sends are all mono. You should not need a DI box to patch it in. Good luck!

~Dave

 

[FMEng]

You need a TRS balanced 1/4" connector.

If you want to solder the XLR back on, you could make an adapter going from XLR to 1/4" but that is the long way around.

This guide will help you with how the soldering should be done. Soundcraft - [Support]

You are basically taking a balanced output and making it unbalanced by putting the ground and signal - together.

Any radio shack will have the right part, go grab it, solder it up... your problem should be solved.

I agree that you need to keep the line balanced to avoid problems, so you'll need to re-do the connector. It's also likely that the console output is un-balanced. Add an Ebtech Hum eliminator, or other transformer to make it balanced.

 

[cjparsons74]

You need a TRS balanced 1/4" connector.

Thanks everyone for your replies.

Footer, if the aux send is a mono socket, do you think this stero jack, wired to the XLR cable will work OK?

For a hum eliminator/transformer, will a spare passive DI box I have do the job? I'll be plugging it in reverse i.e. aux send mono jack-jack into DI box 'output' and Di box XLR 'input' connected to multicore XLR return jack.

Chris

 

[DaveySimps]

Chris, I am not intending to answer on behalf of Footer, but your thinking for "stereo" 1/4" jack is a bit askew. The Tip Ring Sleeve connector is a balanced connector, not a "stereo connector". This is different from a Tip Sleeve connector (like you would use to hook up a guitar to an amp). The Tip Ring Sleeve (TRS) connector still use all 3 conductors, just like an XLR connector. The Tip Sleeve connector uses only two (no ground). The mono aux outs on your board are balanced connectors using female TRS connectors. Hope this clears some things up for you.

~Dave

 

[cjparsons74]

DaveySimps, Footer, thank you.
I didn't realise about the TRS Jack. I'll get one of them and give it a go.

 

[DaveySimps]

Feel free to post again if the info we gave you and the links Footer poster do not answerer all of your questions. Good luck!

~Dave

 

[cjparsons74]

DaveySimps, Footer, thank you.
I didn't realise about the TRS Jack. I'll get one of them and give it a go.

I do have something to add in case anyone else finds this post. I think some of my confusion in replying above was caused by differences in the names of things between the UK and the USA - this wikipedia article is useful, especially "Tip/ring/sleeve terminology". When I mentioned a stereo jack I was talking about the same TRS connector (Left-Right-Ground or Tip-Ring-Ground, same connector, different applications). The wikepedia article goes on to talk about the use of such jacks for small mixer balanced connections.

 

[FMEng]

Thanks everyone for your replies.

Footer, if the aux send is a mono socket, do you think this stero jack, wired to the XLR cable will work OK?

For a hum eliminator/transformer, will a spare passive DI box I have do the job? I'll be plugging it in reverse i.e. aux send mono jack-jack into DI box 'output' and Di box XLR 'input' connected to multicore XLR return jack.

Chris

It wouldn't hurt to try the passive DI, but I wouldn't expect great results. The transformer has a turns ratio, for impedance matching, that would tend to lower the level going to the speaker amp. Line level is hotter that it is designed for, so the core may saturate and cause distortion, especially on bass. But, if it works, it works.

 

[museav]

I do have something to add in case anyone else finds this post. I think some of my confusion in replying above was caused by differences in the names of things between the UK and the USA - this wikipedia article is useful, especially "Tip/ring/sleeve terminology". When I mentioned a stereo jack I was talking about the same TRS connector (Left-Right-Ground or Tip-Ring-Ground, same connector, different applications). The wikepedia article goes on to talk about the use of such jacks for small mixer balanced connections.

I don't think that it is a geographic naming convention issue, rather a sloppy use of terminology that has become common in the consumer and MI world, similar to referring to a two channel amplifier as a "stereo" amp regardless of the application. 1/4" TRS (or RTS in some countries, a nomenclature I never understood) is the actual connection, stereo is the application and when used in reference to a TRS connector inherently refers to unbalanced audio. So a 1/4" TRS connector can be used for either balanced mono or unbalanced stereo audio applications.

 

[TimmyP1955]

It wouldn't hurt to try the passive DI, but I wouldn't expect great results. The transformer has a turns ratio, for impedance matching, that would tend to lower the level going to the speaker amp. Line level is hotter that it is designed for, so the core may saturate and cause distortion, especially on bass. But, if it works, it works.

IF the board's output is an unbalanced TS, and if the connection cannot be made without noise (try lifting the shield at one end, but this won't likely help), a DI is not the answer - you'd need a 1:1 isolation transformer such as Radial Twin-Iso two channel Jensen transformer equipped balanced isolator.

BUT: do you not have an EQ in the foldback chain? I can't imagine not having one, unless you are using IEMs. Connect from the console to the EQ, and the EQ's balanced output will solve the problem.