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stereo AND mono sum from stereo source in a wall box(Install)


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hi all,


im doing an install in a small bar meant only for use by dj's.


I have used 2 powered 15" cabs in bar and a powered 10" in the booth.


all cables are balanced.


I have put a surface mounted box on the wall containing 4x XLR panel sockets Fe/Fe/Ma/Fe (in/in/out/in)


the FIRST TWO sockets feed the two powered 15's and the source is taken from the L & R master out of the mixer.


the FOURTH socket feeds the powered 10 in the booth and the source is taken from the booth out of the mixer.


while most mixers of any quality do have an additional booth out, it is however, not a given. in case of this scenario I would like a mono sum of L & R (1st two sockets) available from the remaining socket (third)


how could I do this?



would this work?-


take a leg off both (L & R) hot pins and put each through a DIODE? or RESISTOR? before attatching both to the hot pin on the output.


repeat on cold pins


attatch both (L & R) screen pins to the screen pin on the output.


I have diagram if it helps.

email me and I will happily send it to you. elliotwhite62517@aol.com



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what you need to do is split the signal twice, I.e have your main feed and the 2nd feed. (buy a lead for that) and then sum that (again with a lead available from cpc as I have 2 myself), or couldnt you just split the booth feed?
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"splitting signal twice then joining"... that won't work - you're just joining them together, so you'll lose stereo. The most important thing to remember is that the audio signals are not clever. They don't know what you're trying to do... :rolleyes:


Any faffing around with resistors is going to introduce some crosstalk, and thus compromise your "main" signal.


And diodes have bo place here.


There are 2 "proper" solutions:


1. Buy a second powered 10" for the booth.

2. Get a simple summing mixer - the cheapest behringer/etc one will do if you're running unbalanced, if balanced you'll need one with 2 balanced inputs.

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I would recommend something like this which is an active splitter / mixer. In your case you would need to use it in Splitter mode by selecting the relevent switches on the unit.


Connect the stereo output of the DJ mixer to the stereo input of this unit, connect the stereo output of this unit to the main inputs on your wall panel and connect the booth speaker to one of the splitter outputs on this unit.


You will also have another five spare outputs available that you could use for other things such as a sound feed to the lighting controllers.



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How about this for a cunning plan - use your existing XLR females for the main PA input as planned, but then have your booth input fed from the output of a simple changeover switch; one side of which is fed from your other XLR female (for mixers with a dedicated booth output) and the other side fed from either an active combiner if you want the best solution, or fed from a simple resistive combiner if a bit of cross-talk doesn't matter or even simpler from one side of the main stereo if you think that most DJs won't notice (obviously you must do what your conscience will allow here).
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cheers for your response. I dnt think a little bit of cross talk would matter so I think I will go with resistive combiner. would you be willing to have a quick look at my diag? what size resistors should I use?



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what size resistors should I use?
Two 10k 2watt resistors should do it! But its a crude solution and will also mono your Main Speakers as well. The AC waveform travels both ways in this setup.


This presents around a 6db ATT in level but shows both the mixer output stage and amplifier input stage a resistance they are happy with.



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If its just for DJ monitor use then surely they wouldn't mind cueing off just one stereo channel? DJ's tend to beatmix either off a high-hat or a bass drum depending on preference, both of these are likely to be present in both L & R channels.
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What you want to do is quite easy realy...


If you want a mono sum then you could use an Alice Mono pack



We use dozens of them all over the place


Alternativly the Sonifex RB-SM1 looks like it would also do the job




Good luck.

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true enough, given the budget up to now (not tiny, wisely used) I dnt think the owner would appreciate £150+ bill souly for (in the rare case a dj has no booth out) making the monitor that WORKS, work a little bit different.


thankyou every1

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any DJ using a desk with no booth out is probably of the calibre where he won't notice that he's only getting the Left signal in his monitor.


My last DJ residency required me to beatmix with no monitors at all! I had to use the house PA then mentally compensate for the delay..not too hard if you've enough experience.

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