How to wire XLR inputs.

[DickyT]

Hi there,

I'm embarking on a subwoofer build. Currently they are wired using standard mono jacks, but ideally I would like to have XLR inputs.

Now, I know how balanced cables work - reversing the phase of one to collect the same interference to be cancelled out at the other end resulting in a +2 signal - but how DO you reverse the phase at the other end?

Thanks, Rich

[GR1]

Um, You might not understand how balancing works ...

 

Is the speaker active - with the amp and possibly crossover built into the cabinet? If it isn't then balancing is irrelevant because you will be feeding the output from a power amp and I would use a Speakon connector. If it is active then just wire it normally.

[DickyT]

Awesome. No, it's passive.

So basically, balancing is needed BEFORE amplification?

Ok, makes my life easier. Cheers!

Rich

[GR1]

Can I suggest that you forget what you think you know about balancing and spend a couple of hours on the internet researching the use of balancing in sound systems. It will be time well spent. Good luck with your subwoofer build.

[paulears]

Use circuit 1-/1+ in the speakon, and just keep the wiring the same both ends.

 

Top Tip on building subs.

 

No matter how stiff you have made them, double check all the bracing, and use plenty of glue and fixings - because subs are a great way to discover your woodworking accuracy isn't so good. Vibrations and buzzes from joints that appear solid - and it's too late to fix in many cases. Biscuits and corner bracing, and more bracing on any larger unbraced panels.

[Simon Lewis]

Rich,

 

Wiki states... "In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits".

It may used used in a differential mode but doesn't have to be!

As GR1 suggests, if you have a passive speaker (i.e. you are connecting loudspeaker level signal to it) then you do not need to consider balancing. However, use of XLRs for loudspeaker connection has fallen out of favour because a) there is no standard for how to wire them b) use of a male output could give rise to dangerous touch voltages or short circuits c) few XLRs can accommodate beefy speaker cable and d) the industry has pretty much adopted the Neutrik Speakon as the de-facto loudspeaker connector.

It would probably make sense to do the same!

Simon

[MarkPAman]

However, use of XLRs for loudspeaker connection has fallen out of favour because a) there is no standard for how to wire them b) use of a male output could give rise to dangerous touch voltages or short circuits c) few XLRs can accommodate beefy speaker cable and d) the industry has pretty much adopted the Neutrik Speakon as the de-facto loudspeaker connector.

 

e) Plugging the output of an amp into the input of a desk is often an expensive mistake.

[sam.spoons]

Have a read of this http://mikeriversaudio.files.wordpress.com/2010/12/balanced-unbalanced_revised.pdf It should answer any questions you may have.

[Simon Lewis]

e) Plugging the output of an amp into the input of a desk is often an expensive mistake.

 

Drat! I had to miss out e) ! Well spotted!

[Doug Siddons]

We did this recently http://www.blue-room.org.uk/index.php?showtopic=57965&st=0&p=475689&hl=balanced&fromsearch=1&&do=findComment&comment=475689

[DickyT]

Awesome, thanks for such a great response.

The reason I figured using XLR jacks was because of some awesome fake turbo subs I use. They use an XLR input, but the out from the amp is indeed speakon. I should know this, but for some reason it has never occurred to me that they have no use for balancing.

Perhaps I should indeed brush up on my knowledge of balancing - thanks for the link, Sam. One look and it's coming flooding back. It'a been a while.

I have been looking at some sub designs, I was think of doing a folded horn design - any suggestion on a good, strong glue type?

[paulears]

My carpenter mate swears by Gorilla wood glue (which I think is just fancy PVA) he buys from screwfix.

 

I've got turbo sound wedges, which I've refitted with Speakons. I really don't know why they used XLRs, but perhaps it was just speakons hadn't been invented?

[Dave SA]

Hate to do this, but if you are this uninfromed regarding the subject I really suggest you do some reading over at: http://forum.speakerplans.com/

 

You will gain a lot from the process. Why not do that then pop back here and tell us what you've learned! :)

[S&L]

Hi have a pair of adlib tops with XLR inputs - they definitely pre-date speakon - I have tails permanently connected to the amps (I do this for a monitor amp also) which convert speakon to XLR and the tails are coloured blue to differentiate from any other cable. I also have XLR to XLR speaker cable coloured blue (you can buy them from cpc) there isn't any practical chance of sticking a powered XLR somewhere it shouldn't go with this particular set up but the colour coding (and L/R labelling) makes sure that the cable is easy to find and hard to confuse with mic cables.

Of course that only works because it's the same people wiring up every show with this set up.