AUXILIARY SENDS

Auxiliary sends are yet another way of taking audio signals out of a mixing desk, but they work quite differently to the way we have just looked at - i.e. routing channels to groups & sending the signal out through the group outputs. Also auxiliary sends are used for specific purposes & these are:

  1. Effects loops
  2. Monitor or foldback mixes.

EFFECTS LOOPS

Very often you will want to add effects, such as reverb, to audio signals. A reverb effect can simulate an acoustic space & make it sound as though our harp player was performing in a concert hall or a cathedral perhaps. Humans like the sound of reverberation, so it is common to use it for live sound & recording.

For an effects loop you would have to make sure that the auxiliary send was set to "post fade." This means that the signal exiting the auxiliary send is affected by the channel's fader. So on our harp signal this would mean that as we fade their channel fader on the mixing desk, the level of reverb would fade correspondingly. (If the auxiliary were set to "pre fade" this would mean that the signal exiting the aux. send would not be affected by the channel fader. This would mean that if you faded the harp player's channel all the way down you would still hear the reverb. (This is not normally what is required.)

Aux

INSTRUCTIONS FOR SETTING UP AN EFFECTS LOOP

  1. Take a lead from the auxiliary output of the mixing desk to the input of the effects unit.
  2. Open the auxiliary master pot. (While the master auxiliary pot is closed, no signal will get out of the auxiliary output.) On the diagram above you can see the master auxiliary pot is open at about 2 o'clock
  3. Make sure the auxiliary send is set to be "post fade."
  4. Decide which channels you wish to send to the effects unit. In the example above you can see that the acoustic guitarist's & flute player's signal are not being sent to the auxiliary output. The harp is & even more of the bodhrán signal is being sent to the effects unit via the aux. send. This will mean that the bodhrán has more effect on it than the harp.
  5. Take a lead (or 2 leads if the effects unit is stereo) from the effects unit's output & return these leads into spare channels on the desk or the effects returns. Turn these up & you will be able to hear the reverb on the harp & bodhrán.

MONITOR MIXES & FOLDBACK

Often you will need to set up a mix that is completely independent to the mix that is being sent to the audience or to a recording device. Take for example a band playing on stage. A mix of their signals will be sent to the audience, but what does the musician need to hear on stage in order to perform? Is the mix he/she wants to hear on stage going to be the same as the mix that the audience hears? Very often the answer is "no."

Let us assume that each of our performers has a speaker in front of them so that they can hear what they & their band mates are playing on stage. What instrument do you think that the bodhrán player will want to hear most loudly in their speaker? The answer of course is their own instrument - the bodhrán.

Auxiliary sends allow you to set up independent mixes for each member of the band, so that each musician can choose what they want to hear in their own personal monitor speaker or headphones. In this case the aux. sends need to be set up to be "pre-fade." This means that any adjustments made to the faders on the individual channels will affect the audience mix but not the auxiliary mix going to the musician's monitors.

Look at the diagram above but this time imagine a lead from the auxiliary output goes to an amplifier & speaker in front of a musician. You can see that none of the acoustic guitarist's or flute player's signal will be sent to the monitor, some of the harp signal will be sent to the monitor & more bodhrán signal will be sent to the monitor.

Nothing you do to the channel faders will affect the mix going out of the aux. output if it is set to "pre fade." In essence you are using each channel's aux. send pot to produce a mix to be sent out of the aux. output. If there were four players in your band, you would need to set up four mixes using four different aux. sends. One for each member of the band. This explains why large desks frequently have many aux. sends.

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