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Separate mixer for monitors?


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I always see separate monitor boards on stage, explain to me how this is done. I only have two free aux sends on my board, if I added a second board for monitors, would this number be increased? This may be a stupid question, but I have never done this nor have I ever asked how it was done, so I figured I would ask the experts.

Also, is it possible if I have two monitor mixes to use one single channel EQ for both? Another dumb question probably.

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Originally posted by Norton666

I always see separate monitor boards on stage, explain to me how this is done. I only have two free aux sends on my board, if I added a second board for monitors, would this number be increased? This may be a stupid question, but I have never done this nor have I ever asked how it was done, so I figured I would ask the experts.

Also, is it possible if I have two monitor mixes to use one single channel EQ for both? Another dumb question probably.

Don't you think you'd rather just upgrade your Behr board to something with more sends? Anyway,an actual monitor board has channel ins and outs. Signal (mic,line,etc)goes into a channel on the monitor board and then passes back out to your channel on the FOH mixer.

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tlbonehead has the right idea, but with few exceptions the wrong implementation.

 

On a concert stage all microphone and D.I. 's run direct or through sub-snakes to a splitter. One monitor mixer that has a built-in split is the Soundcraft Spirit monitor board, but most do not. The splitter is generally a separate box with XLR inputs and outputs or XLR inputs and some kind of mass connector output, capable of outputting many channels on one connector.

 

The norm is to run a short mass connector from a dedicated output to the monitor console. The console end is separated into individual channels terminated in XLRm connectors.

 

Another mass connector with a far longer cable runs to FOH. Depending on the set up, one or the other console may have the direct run to the mics and be responsible for providing phantom power to mics and D.I.s that need it. The other splits are either transformer or electronically isolated from the inputs. The board(s) on that split cannot pass phantom to the mics.

 

The result of this is a giant, multiple "y" jack for every input. That way the monitor console is fully independent from FOH.

 

This is important for three main reasons.

 

First, it frees the monitor consoles outputs (which dedicated monitor consoles have many more of than a FOH console) for mixes independent of the FOH mix.

 

Second, it allows independent eq on each channel for the bands' mixes. The needs of FOH and the speakers used are rarely the same as those onstage as monitors.

 

Third, it allows a wider range of control to the monitor mixer, who by definition is separate from the FOH mixer. In other words, someone is always concentrating on the band rather than on both FOH and monitors.

 

For a small system, Whirlwind and others make splitter snakes. These snakes have XLR inputs in a typical, snake-stage-box and permanently wired snake cables for monitors and FOH. one is short, the other long. (I think 25' on the monitor side and 100'+ on the FOH side.)

 

But none of this will help you if you don't have someone skilled in running monitors for your band.

 

Hope that explains some things you wanted to know.

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Probably won't hurt anything BUT it can cause currents to flow in ways that were not anticipated in the design of either mixer and cause unpredictable noise issues, plus the input impedance will be significantly lower due to the paralleling of phantom power source resistors.

 

Input blocking caps wouldn't be a problem since the polarity would always be correct no mattere where phantom power came from.

 

Carey can probably add some more info since mixers are his specialty.

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Originally posted by agedhorse

Probably won't hurt anything ..... Carey can probably add some more info since mixers are his specialty.

 

Yes, as Aged says, won't hurt anything on a properly designed mixer.

 

Speaking for A&H, our mic preamps are designed to withstand any aspect of phantom power abuse or misuse. Switching on phantom power at both the FOH and monitor console is certainly no problem.

 

A lot can be said about the technical aspects, the effect on voltage, the effect on impedance and so on. In fact, there can even be a technical advantage in powering from both, but it really has no effect on the mic performance worth worrying about.

 

Where you switch phantom power is down to user preference. For me, I like to switch it at the monitor board as that is closest to where the mics are plugged up. The FOH guy is often on stage helping the monitor guy during stage change over so it makes sense to switch it there. Just make sure all the stage mics are muted on the house console while it is unattended.

 

Regards,

Carey

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somewhat unrelated question,

 

if i am building my own splitter, should the grounds on the split be connected at the stage box? if i am powering my monitor and foh board from the same source and ground, when the grounds on the split are connected don't i create a loop?

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Lifted on the split at the stage box generally works best and is more technically correct (providing of course your direct path including phantom power) is not isolated.

 

It really depends though, as there are more than one type of ground to consider. RF grounding is a big challange for example.

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Thanks for the info, Agedhorse and Carey.

 

I like the phantom to come from monitor world for the same reasons mentioned by Carey, however I know many operators who run it from FOH for the simple reason that they don't always run a monitor console. Usually if the splitter is connected through multi-channel, mass connectors, you can reverse FOH and monitors as you please, so long as the operators are aware who is on what split. ;)

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